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Extensive areas of agricultural land have been abandoned in recent years through the world and become a significant C sink to mitigate anthropogenic CO2 emissions. Guizhou is the center of South China Karst and about half of its farmland is on sloping fields. Since 1990 more than one third slope farmland has been returned to ecological restoration. However, there is no direct measurement of CO2 flux follow abandonment and restoration in this area. Recently, an ongoing study of carbon flux between abandoned farmland and atmosphere has been carried out at Puding Karst Ecosystem Research Station in Guizhou province. The studied farmland was abandoned to natural recovery at 2010 and the monitoring work began at March 2015. The carbon fluxes through each part of the ecosystem were monitored simultaneously with an eddy covariance flux tower to observe near surface ecosystem turbulent exchange, a LI-8150 Automated Soil Gas Flux System to observe soil respiration at 8 plots in the field, an LGR's Carbon Dioxide Isotope Analyzer with 8 gas inlets to observe cave CO2 dynamic underground. Preliminary results show: First, the ecosystem was a carbon sink after 5 years' restoration with an annual average NEE about 290 g C/m2/a between April 2015 to March 2017, the carbon sequestration capacity is more than twice during the rainy season than dry season; Second, the coupled soil temperature and soil water content change is the main environmental factor to control soil respiration; Third, cave CO2 mainly came from a mixture of soil respiration and vadose zone air, it changes from about 18000 ppm at autumn to about 2000 ppm at summer depending on different ventilation pattern, therefore its role as a temporary carbon pool and passage cannot be ignored for carbon cycle study in karst region. Further studies need to quantify the interactions of the carbon fluxes within the ecosystem as the succession proceeds. [ABSTRACT FROM AUTHOR]

Atmospheric ammonia (NH3) is an important precursor to fine particulate matter in the atmosphere, adversely affecting air quality, climate and biodiversity. Agricultural activities are the predominant source of NH3, including the volatilization of N fertilizers such as urea. At the same time, it is known the ammonia can undergo bi-directional exchange with terrestrial ecosystems. Therefore, it is important to quantify the variability of ammonia exchange between crops and the atmosphere across the growing season to better understand the fate of N applied as fertilizer. The study presents direct eddy covariance (EC) NH3 flux measurements from a urea-fertilized corn field in Ottawa, Canada, over two growing seasons in the years of 2017 and 2018. A flux tower was equipped with a 3-D sonic anemometer (CSAT3; Campbell Scientific, UT), and a fast time-response Quantum Cascade Tunable Infrared Differential Absorption Spectrometer (QC-TILDAS; Aerodyne Research, MA) for NH3 measurements at 10 Hz. During the 2017 season, NH3 emissions reached up to 500 ng m2/s within one week after fertilizer application. As the canopy started growing, the NH3 emissions decreased and by the end of the growing season deposition dominated. In 2018, there was little evidence of NH3 emission immediately following fertilizer application, but sustained emissions occurred following a rainfall event two weeks later. The roles of soil chemistry, atmospheric composition, turbulence, and climate variables in regulating the ammonia fluxes will be presented. [ABSTRACT FROM AUTHOR]

The study of land surface-atmosphere flux exchanges for mountainous regions has increased in the last decade. However, the prediction of water losses and energy fluxes in natural and disturbed environments of highland biomes is still unexplored. This is the case of the Neotropical Andean biome of the páramo, where this lack of research is noticeable for energy fluxes (net radiation; sensible, latent and soil heat) and actual evapotranspiration (ETa). The present investigation assessed the parameterization of a state-of-art Land-Surface Model (LSM) for the prediction of energy and ETa fluxes in representative páramo catchments of southern Ecuador. The LSM Community Land Model (CLM ver. 4.0) outputs were evaluated with (i) surface-level fluxes from the highest Eddy Covariance tower of the Northern Andean páramo Ecoregion, with complementary micrometeorological sensors; (ii) with remote sensing-derived ETa from an energy balance-based model (METRIC with Landsat imagery); (iii) and with ETa obtained from the closure of water balances of the catchments (WB). The CLM's energy estimates exhibited a clear underestimation on net radiation, sensible and soil heat fluxes, and showed a small overestimation on latent heat flux. On the other hand CLM derived ETa exposed a good correlation (Pearson R = 0.82) comparable to METRIC derived ETa (R = 0.83). However, a poor performance of WB derived ETa was observed (R = 0.46). Our findings highlight the CLM's plausibility for forecasting energy and ETa exchanges for this remote and fragile tropical biome, and provide insights on the ETa methods selection. This study contributes to the ecosystem functioning knowledge regarding the point and spatial-scale water losses through evaporative processes. Finally, it also provides support on the development of further LSM parameterizations for climate / land use change scenarios in this sensitive highland region. [ABSTRACT FROM AUTHOR]

A severe nuclear accident occurred in March 2011 at the Fukushima Dai-ichi nuclear powerplant (FDNPP) operated by the Tokyo Electric Power Company (TEPCO), causing seriousenvironmental contamination of radionuclides over wide areas covering eastern Japan and thewestern North Pacific. Igarashi et al. (2015) reported the impacts from the FDNPP accidentover 3 years in Tsukuba, Ibaraki (ca. 170 km southwest from the FDNPP). The monthlyatmospheric 90Sr and 137Cs deposition fluxes in March 2011 reached approximately 5Bq/m2/month and 23 kBq/m2/month, respectively, which are 3–4 and 6–7 orders ofmagnitude higher, respectively, than those before the accident. Even after 7 years of theaccident, high levels of 137Cs are found in ambient aerosols from some areas of Fukushimaespecially during rain event. We presume that biological processes such as fungalactivity emit radionuclides deposited over soil to the atmosphere. Fungi can uptakevarious metal ions including potassium and 137Cs from soil using the soil networksystem. To prove the hypothesis, we collected ambient aerosols (day and night, n=40) fromNamie-cho in Fukushima, Jpan in August to October 2017 using quartz fiber filters and highvolume air sampler. The aerosols samples were analyzed for 137Cs using a Ge-semiconductordetector. An aliquot of filter samples were extracted with dichloromethane/methanol (2:1)mixture. The extracts were concentrated using a rotary evaporator under vacuum and thenreacted with BSTFA reagent to derive TMS derivatives of sugar compounds. The derivativesincluding fungal organic tracers were measured using a gas chromatography/massspectrometer. We detected high levels of fungal tracers such as arabitol, mannitol andtrehalose in the aerosol samples. Interestingly, nighttime samples showed a positivecorrelation between trehalose and 137Cs, although there is no correlation in daytimeaerosols. Similar correlations were not observed for another fungal spore tracerssuch as arabitol and mannitol. The results will be discussed from the viewpoint ofsoil-to-air re-suspension of 137Cs via biological and meteorological soil/air interaction. [ABSTRACT FROM AUTHOR]

Microbial processes are responsible for converting micro- and macronutrients into forms thatcan be utilized by plants, as well as nutrient loss channels, for example through denitrification(which releases nitrous oxide) and methanogenesis (which releases methane). Thebiological activity in the soil is therefore a direct window into the health of the soil. Theisotopic composition of soil trace gases reflects the microbial pathways that produce them,making these gases effective messengers of bioactivity. Here we present results fromlaboratory testing of new diffusive soil probes coupled to a nitrous oxide/methane isotopeTILDAS (Tunable Infrared Laser Direct Absorption Spectrometer). The TILDAS issensitive to the common N2O, 15N14N16O, 14N15N16O, 14N14N18O, common CH4, and13CH4 species. The number of probes in the system is scalable, opening up thepossibility of spatially and temporally-resolved mapping of subsurface biologicalactivity. Tests using abiotic silica sand demonstrates the efficacy of these probes. We will also present results from sampling gases in tropical rainforest soil fromBiosphere 2. Drying the soil, irrigating it, and exposing it to different oxygen levelsreveals variations in N2O and CH4 concentrations, as well as isotopic signatures. [ABSTRACT FROM AUTHOR]

Sugarcane is a bioenergy crop widespread in Brazil to be responsible to supply ethanol as analternative source for fossil fuels consumption. As the highest sugarcane producer in theworld, Brazil has been observed the consequences of the increased demand for ethanol:sugarcane crops are expanding mainly toward Brazilian Midwest. Such region has extensivelow-intensity pastures in which livestock is carried out. Livestock to meat production is alsorelevant to Brazilian economy, hence, it is expected an increase of high-intensity pasture tocompensate sugarcane expansion. Furthermore, soils of low-intensity pasture are often citedas carbon sinks with low greenhouse gases emission rates, in this agricultural ecosystememission dynamics may be alter since for land use change from low-intensity pasture tosugarcane it is necessary tillage and fertilization. Thereby, researchers are trying tounderstand if the sugarcane sustainable life cycle could be affect by it expansionto pasture areas. Taking to account the above mentioned a field experiment wasset up in São Paulo State to quantify N2O fluxes and estimate emission factors insugarcane over four years, as well as, in low-intensity and fertilized pasture duesynthetic fertilizer applications. Treatments were sugarcane with (S+F) and without(S−F) fertilizer, low-intensity pasture (PLI) and fertilized pasture (PF) (n=4). Soilcharacteristics were similar to the entire experimental area. Sugarcane plantingfollows the conventional soil tillage system while to pasture treatment there were notill-operations. Fertilizer sources where NH4NO3, superphosphate and KCl and the ratesfollow Brazilian agricultural practices. To quantify N2O fluxes gas samples werecollected during more or less intensive events from October 2013 to September 2018.Gas samples were collected from PVC cylindrical chambers. Soil temperature andweather conditions were also recorded. During sampling events, four samples werecollected from each chamber and stored in vials at 1, 10, 20 and 30 min-intervals. Gasconcentrations in vials were determinated by gas chromatography and fluxes calculationsaccording Carmo et al. (2013). Generally, fertilized treatments (S+F and PF) showedhighest N2O fluxes and annual emissions. During the four years sampled, N2O fluxespeaked at 22.77, 15.32, 21.65 and 4.5 mg m−2 day−1in S+F and at 0.67, 14.40,12.77 and 1.57 mg m−2 day−1inPF. What means that, in S+F maximum fluxeswere 27.01, 94.78, 97.97 and 80% highest than in S−F and in PF, except to 2013,were 61.11, 31.42 and 26.11% highest than PLI. From 2013 to 2018 emissionsfactor in S+Fwere 0.46, 0.18, 0.16 and 0.11% and in PF were 0.41, 2.24, 0.56 and0.46%, such sugarcane results are lower than 1% IPCC estimations but agreed withBrazilian observations. N2O emissions factors in the first year were higher in thesugarcane than in pasture, after this, in the ratoon periods, were always higher inpasture. By now, the data indicate a potential negative effect of pasture fertilization ongreenhouse gas emissions and confirm the sustainable profile of the sugarcane. [ABSTRACT FROM AUTHOR]

Tenerife (2,304 km2), the largest of the Canary Islands, has developed a central volcanic complex (Cañadas edifice), that started to grow about 3.5 My ago. Coeval with the construction of the Cañadas edifice, shield basaltic volcanism continued until the present along three rift zones oriented NW–SE, NE–SW and NS (hereinafter referred as NW, NE and NS respectively). Main volcanic historical activity has occurred along de NW and NE rift-zones. Uprising of deep-seated gases occurs along the aforementioned volcanic structures causing diffuse emissions at the surface environment of the rift-zones. In the last 20 years, there has been considerable interest in the study of diffuse degassing as a powerful tool in volcano monitoring programs, an important monitoring task mainly at those volcanic areas where visible manifestations of volcanic gases are absent. Soil gas and diffuse degassing surveys have been focused in CO2 because it is, after water vapor, the most abundant gas dissolved in magma. One of the most inexpensive methods to determine CO2 fluxes is based in the absorption of CO2 through an alkaline medium, followed by titration analysis. In the summer of 2016, a network of 31 closed static chambers was installed, covering the three main structural zones of Tenerife (NE, NW and NS) as well as Cañadas caldera with volcanic surveillance porpoises. 50 cc of 1N KOH solution is placed inside the chamber to absorb the CO2 released from the soil. The solution is replaced weekly and the trapped CO2 is then analyzed at the laboratory by titration. Results are expressed as weekly integrated CO2 efflux values. The CO2 efflux values ranged from 2.7 to 12.5 g•m-2•d-1, with average values of 8.2 g•m-2•d-1 for the NE rift-zone, from 3.1 to 10.9 g•m-2•d-1, with average value of 6.3 g•m-2•d-1 for the NW rift-zone, and from 2.3 to 10.9 g•m-2•d-1, with average value of 6.3 g•m-2•d-1 for NS rift-zone. In the case of Cañadas caldera, values ranged from 1.1 to 8.0 g•m-2•d-1, with average value of 5.0 g•m-2•d-1. The most significant CO2 efflux values were observed at the NE rift-zone, with a maximum value of 12.5 g•m-2•d-1. Soil gas samples were weekly sampled on the head space of the closed chambers to analyze the chemical and isotopic composition of CO2. The gas is considered as CO2-enriched air, showing concentrations of CO2 in the range 355-22,448 ppmV, with average values of 4,959 ppmV, 1,274 ppmV, 1,465 ppmV and 609 ppmV for the NE, NW, NS rift-zones, and Cañadas caldera, respectively. The CO2 isotopic composition indicates that most of the sampling sites exhibited CO2 composed by different mixing degrees between atmospheric and biogenic CO2 with slight inputs of deep-seated CO2, with mean values of -21.4‰, -14.1‰, -16.6‰ and -11.9‰ for the NE, NW, NS rift-zones, and Cañadas caldera, respectively. The methodology presented here represents an inexpensive method that might help to detect early warning signals of future unrest episodes in Tenerife. [ABSTRACT FROM AUTHOR]

Mt. Ontake (3067 m.a.s.l.) is a stratovolcano located in central Honsu and around 100 Km northeast of Nagoya, Japan, with the last eruption occurring on September 27, 2014, killing 57 people, and creating a 7-10 km high ash plume (Kagoshima et. al., 2016). There were no significant earthquakes that might have warned authorities in the lead up to the phreatic eruption and at the time of the eruption there was no operational geochemical surveillance program. In order to contribute to the strengthening of this volcanic surveillance program, the Disaster Mitigation Research Center of Nagoya University and the Volcanological Institute of Canary Islands started a collaborative program in 2016. An automatic geochemical station was installed at Ontake volcano and soil diffuse degassing surveys of CO2 efflux and other volatiles at the surface environment of selected areas of the volcano were established with a periodicity every two years. The station was installed 10.9 km east away from the eruptive vent, where some earthquakes occurred, and consists of a soil radon (Rn) monitor (SARAD RTM-2010-2) able to measure 222Rn and 220Rn activities. Monitoring of radon is an important geochemical tool to forecast earthquakes and volcanic eruptions due to its geochemical properties. The volatile and short-lived nature of 222Rn means that variations in 222Rn activity can be used to map fluid flow along active faults and fractures in volcanic areas. Regarding to the soil diffuse gas surveys, the first survey was carried out in August 2016 and the last one in October 2018, with 194 and 197 measurement points respectively, covering in an area of ⁓91 km2. Measurements of soil CO2 efflux were carried out following the accumulation chamber method by means of a portable soil CO2 efflux instrument. To estimate the total CO2 output, sequential Gaussian simulation (sGs) was used allowing the interpolation of the measured variable at not-sampled sites and assess the uncertainly of the total diffuse emission of carbon dioxide estimated for the entire studied area. The total emission rate of diffuse CO2 efflux was expressed as the mean value of 100 equiprobable sGs realizations, and its uncertainly was considered as one standard deviation of the 100 emission rates obtained after the sGs procedure. During the last survey of 2018, soil CO2 efflux values ranged from non-detectable up to 86 g•m-2•d-1 with an average value of 19.00 g•m-2•d-1. The average value of soil CO2 efflux for 2016 survey was in the same order, 22 g•m-2•d-1. The estimated average value for the total diffuse CO2 released for the Mt. Ontake volcanic complex during this study of 2018 was 1,755 ± 56 t•d-1 vs. the 2,107 ± 69 t•d-1 estimated in 2016. Periodic diffuse CO2 emission surveys are a powerful volcanic surveillance geochemical tool. It is expected for future surveys to obtain a long-term evolution to understand the dynamics of diffuse CO2 emission and its relationship with the volcanic activity of Mt. Ontake. Kagoshima et. al., 2016 J. Volcanol. Geotherm. Res. http://doi.org/10.1016/j.jvolgeores.2016.06.013 [ABSTRACT FROM AUTHOR]

La Palma Island (708.32 km2) is located at the northwestern end of the Canarian Archipelago. Subaerial volcanic activity on La Palma started ~2.0 My ago and has taken place exclusively at the southern part of the island in the last 123 ka, where Cumbre Vieja volcano, the most active basaltic volcano in the Canaries, has been constructed. On 7-9 and 13-14 of October 2017 two intense seismic swarm occurred beneath Cumbre Vieja. Seismological and geochemical evidences linked the seismic swarm to a deep-seated magmatic intrusion. In the last 20 years, there has been considerable interest in the study of diffuse degassing as a powerful tool in volcano monitoring programs. Diffuse degassing studies are even more important volcanic surveillance tool at those volcanic areas where visible manifestations of volcanic gases are absent, such as Cumbre Vieja. Historically, soil gas and diffuse degassing surveys in volcanic environments have focused mainly on CO2 because it is, after water vapor, the most abundant gas dissolved in magma. One of the most popular methods used to determine CO2 fluxes in soil sciences is based on the absorption of CO2 through an alkaline medium, followed by titration analysis. In October 2017, a network of 21 closed static chambers was installed, covering Cumbre Vieja volcano with volcanic surveillance porpoises. 50 cc of 1N KOH solution is placed inside the chamber to absorb the CO2 released from the soil. The solution is replaced weekly analyzed at the laboratory by titration. Results are expressed as weekly integrated CO2 efflux values. The CO2 efflux values ranged from 1.7 to 15.6 g•m-2•d-1, with an average value of 7.4 g•m-2•d-1 for the entire Cumbre Vieja volcano. Stations showing highest values (> 13 g•m-2•d-1) are located at the southern end of Cumbre Vieja where the most recent volcanic eruption took place and on the northwest flank of this volcanic system. Soil gas samples were weekly sampled on the head space of the closed chambers to analyze the chemical and isotopic composition of CO2. Collected gas samples can be considered as CO2-enriched air, showing concentrations of CO2 in the range 305-158,211 ppmV, with an average value of 2,237 ppmV. The highest values of CO2 concentration coincided with those stations that showed the highest CO2 efflux values. Regarding to the CO2 isotopic composition, expressed as C-CO2, most of the stations exhibited CO2 composed by different mixing degrees between atmospheric and biogenic CO2 with slight contributions of deep-seated CO2, with values ranged from mean values of -2.40‰ to -29.0‰, and an average value of -19.4‰. Three stations located along the southern most part of the NS rift of Cumbre Vieja volcano showed values with a strong deep-seated CO2 contribution, occurring at the same time that the observed increase on the diffuse CO2 emission along the Cumbre Vieja measured by the accumulation chamber method. The methodology presented here represents an inexpensive method that might help to detect early warning signals of future unrest episodes at Cumbre Vieja. [ABSTRACT FROM AUTHOR]

Subnivean soil respiration can be responsible for a dominant portion of an ecosystem's winter carbon budget which in turn provides a notable amount of the total annual budget. Despite this, challenges surrounding subnivean respiration measurements--disturbance of overlying snowpack, potential obstruction of automatic chambers, and uncertainties involved in the gradient method--leave the topic understudied. However, Forced Diffusion (FD) chambers use membranes to passively moderate and measure gas flux through the unit, resulting in a lack of externally moving parts and making them suitable for direct subnivean respiration measurements.Here, we present laboratory flux-generator and in-situ field site results showing biases present in such measurements, caused by factors such as localised concentration gradients, preferential pathways, and disturbance of FD chamber calibration factors, and assess the performance of a "shield" attachment designed to mitigate these issues. Additionally, we present data showing respiration patterns measured prior to snowfall, in the presence of snowpack, and during snowmelt periods. This is supplemented with an examination of how flux measurements scale with snow-depth via artificially cleared and enhanced snowpack plots. Finally, we show how soil chambers can be be used to supplement eddy-covariance measurements and provide a deeper understanding of wintertime carbon dynamics. [ABSTRACT FROM AUTHOR]

Background Drained peatlands, especially cultivated peatlands, are significant sources of greenhousegases (GHG), such as carbon dioxide (CO2) and nitrous oxide (N2O). In Finlandapproximately 13.6% of the total arable land area is made up of organic soils (e.g. peatlands),and therefore it is important to find ways to reduce the GHG emissions from these soils.Previous studies suggest that e.g. wood ash addition to forested peatland has potential todecrease N2O emissions, but it may also increase CO2 emissions. Both N2O and CO2emissions originate from microbial processes that can be greatly affected by changes in thechemical and physical composition of the soil. In general, changes in microbialactivity and population structure are attributed to changes in soil pH and electricalconductivity. In this study, we aim to test the effect of multiple soil amendmentsubstances in laboratory incubation experiment to see how they change the chemicalcomposition and GHG emission rates from soils gathered from several cultivatedpeatlands, and if the structure of the soil microbial community can be linked to the GHGemissions. Methods The soil amendments that I plan to study in my experiments are gypsum (CaSO4* 2H2O),wood ash, lime (CaCO3), biochar, and foundry sand. I have conducted the first set of bottleincubation experiments in laboratory, to determine the GHG emission rates from different soilsamples after soil amendment addition. For the experiment, we selected soil samples fromseveral different cultivated peatlands, and to observe the effect of soil amendment addition onsoils that come from different stages of the life cycle of cultivated peatlands, we decided toinclude forested and afforested sites as well. Following this experiment, my plan is to conducta long-term incubation on packed soil cores, with the intent to further study if the GHGemission rates change during long-term incubation, and to measure possible nitrousacid (HONO) emissions from the soil. In this experiment, I also aim to study if themicrobial community structure changes after incubation with different soil amendments. [ABSTRACT FROM AUTHOR]

Tropical Dry Forest are an important global carbon sink, with fundamental ecologicalfunctions of capture, regulation, and supply of water resources. However, due to theseasonality with prolonged dry season water is the most limiting resource for growth. Eventhough Tropical Dry Forest represents 42% of all tropical forests, studies dealing with theircarbon and greenhouse gas (GHG) exchange are still scarce. The aim of this study was toevaluate the seasonal variations of soil CO2, N2O and CH4 fluxes in a Tropical Dry Forest.We evaluated three different land covers in the Tropical Dry Forest Santa Rosa National Parkin Costa Rica i.e. advanced forest succession, early succession, and pasture: At each site soilGHG exchange was measured by replicated (n=6) dark static chamber technique.Measurements were taken between 8:00 and 9:00 am twice a week at each siteduring the period of dry/wet transition season (May-June) and monthly during therainy season (July-December) in the year 2018. Over the same period, the NEE(net ecosystem exchange) at the late stage forest site was measured using an Eddycovariance flux tower. Our results show that in the dry season soil fluxes remainlow and with the start of the first rain events, we see large pulse emissions at allsites caused by the "Birch effect." Moreover, these high pulses were lower in thepasture (CO2 24.50 ± 18.29 mg C m−2 h−1, N2O1.58 ± 1.88 μg N m−2 h−1, andCH4-4.86 ± 8.10 μg C m−2 h−1), followed by the late forest succession (CO2 38.38± 21.78 mg C m−2 h−1, N2O17.39 ± 21.48 μg N m−2 h−1, and CH4-24.57 ±10.52 μg C m−2 h−1) and the early succession (CO2 50.67 ± 20.7 mg C m−2 h−1,N2O21.37 ± 34.02 μg N m−2 h−1, and CH4-3.23 ± 16.77 μg C m−2 h−1). The earlystage forest had the highest soil fluxes, probably due to the higher accumulation oforganic matter and dieback of microbial biomass in the soil during the dry season.The ecosystem NEE measured with the eddy covariance tower at the beginning ofthe rainy season was of 4154.01 ± 2782.68 mg C m−2 d−1reaching maximumvalues of 8184.98 mg C m−2 d−1. The total GHG exchange from the soil varies forall sites going from ∼2 kg CO2-C equiv ha−1d−1 in the dry season, to >15 kgCO2-C equiv ha−1d−1 in the transition season and >5 kg CO2-C equiv ha−1d−1in the rainy season. Soil moisture is the main driver for soil respiration and soilgreenhouse gasses in this ecosystem, however, the current and historic land useand stage of forest succession also affects differently the accumulation and releasedynamics of soil greenhouse gasses to the atmosphere in tropical dry forest soils. [ABSTRACT FROM AUTHOR]

The composition of volcanic gases varies widely between volcanoes and is also dependent on the individual volcano’s state of activity. The emitted gases include H2O, CO2, SO2, HCl, HF, H2S, CO, H2, HBr, HI and Hg, in descending order. A well established remote sensing method to monitor volcanic degassing and eruptive activities is the measurement of SO2 fluxes, which is often combined with in-situ sampling of SO2 and other volatiles(CO2,HCl) and the calculation of the respective gas ratios (e.g, CO2/SO2, HCl/SO2). Those data are used to evaluate the degassing regime, since the gas ratios and emission fluxes evolve during magma decompression according to the individual volatile solubilities. Santa Ana and San Miguel are volcanoes along the Central American Volcanic Arc, where the magmatism is related to the near-orthogonal convergence of the Caribbean Plate and the subducting Cocos Plate. Both volcanoes belong to the most active ones in El Salvador, with their SO2 emissions varying between of 11 - 609 tons per day for Santa Ana with an average of 221 tons per day during 2018, and a range between 21 – 1379 tons per day for San Miguel with an average of 326 tons per day for the same year. Since 2008, both volcanoes are monitored within the Network for Observation of Volcanic and Atmospheric Change (NOVAC), which continuously monitors their SO2 emissions. However, these volcanoes are still poorly studied with only a few published gas data (Rodriguez et al. 2004,Olmos et al. 2007, Barrancos et al. 2008, Colvin et al. 2013, Laiolo et al. 2017), reporting usually (only) SO2 emissions. In January and February 2014, CO2, SO2, HCl and HFoutput rates were measured at San Miguel volcano using a MultiGAS instrument, aFLAME station and a solar ocular FTIR. The average of CO2/SO2, HCl/SO2 and HF/SO2 mass ratio reported were 0.95, 0.13 and 0.016, respectively, in fact representing thefirst ever measurements of CO2, HCl and HF from San Miguel (Granieri et al.,2015). Accordingly, Hasselle et al. 2017 presented the first compositional data for Santa Ana’s gas plume (CO2, SO2, H2S and H2), measured in March 2017. As preliminary results a CO2/SO2 ratio between 21 and 99 (plateau and lake shore, respectively), and a H2/SO2 ratio between 0.34 (lake shore) and 2.44 (plateau) were reported. In this study, we present and compare SO2 long-term data of San Miguel and Santa Ana obtained from the NOVAC stations (2008-2017) and new data gained from in-situ measurements using a multi-sensor instrument obtained during a field campaign in El Salvador in January - February 2019. The aim of the study is an improved characterization of these two volcanic systems. The extended data set will be discussed in context with the former reported data and visual volcanic activity observations and the regional geological settings. [ABSTRACT FROM AUTHOR]

Eddy covariance (EC) technique is largely applied for monitoring carbon dioxide (CO2), water (H2O) and energy exchanges between land ecosystems and atmosphere. The use of EC is currently increasing and now more than 700 globally distributed sites are monitored. Additionally, the monitored study sites are often grouped in network (e.g. FLUXNET). EC allows the continuously monitoring of fluxes at fine (subdaily) time resolution over the growing season. However, only net fluxes can be directly measured, while the source signals must be retrieved by models. In the case of CO2, EC measured the net ecosystem exchange (NEE), that is the net balance between two gross CO2 fluxes: the CO2 uptake from atmosphere by (ecosystem level) photosynthesis or gross primary production (GPP) and the CO2 released in the atmosphere by ecosystem respiration (RECO). The partitioning methods applied in FLUXNET dataset allow to retrieve RECO and GPP from NEE and they made use of non-linear relationships and few meteorological drivers. In fact, the Lloyd & Taylor equation and air temperature are used for estimating RECO; GPP is retrieved by the Michaelis & Menten equation making use of the incoming radiation and vapor pressure deficit as drivers. These approaches are based on strong knowledge assumption and allow a large applicability; however there are limitations in particular when additional drivers have important effects on fluxes variability or when functional relationships deviate from the prescribed ones. In this experiment we investigated the feasibility to use a customized neural network algorithm (NNcust) for CO2 fluxes partitioning. NNcust have been designed for estimating NEE by simultaneously retrieving GPP and RECO. The two gross CO2 fluxes have been retrieved by two subnetworks each one using specific and comprehensive micrometeorological drivers from soil and atmosphere. We investigated many features of the partitioned fluxes and the comparison with FLUXNET standard methods have been carried out. The results showed high consistency between magnitude of partitioned fluxes by NNcust and standard methods implemented in FLUXNET such as in the seasonal, daily, subdaily variability and in the functional relationships between inputs and outputs. However, small (in magnitude) but consistent differences emerged by the comparison of the diurnal cycle of gross CO2 fluxes that could be linked to deviation in modeled functions, the interaction of drivers or to the inhibition of leaf respiration in daytime condition, differently accounted in the modeled output. [ABSTRACT FROM AUTHOR]

Rewetting of dry soil results in a well-known short-term pulse of CO2 from soil to the atmosphere known as the 'Birch effect'. The displacement of CO2 in air-filled pores with water during wetting has been recognised as one of the sources of this pulse. The Birch effect has been extensively reported under wettable soil conditions, but some studies report a lack of such response, suggesting soil water repellency (SWR) as a potential cause. SWR restricts infiltration and affects soil water distribution. Preferential flow paths and increased overland flow are common patterns in water-repellent soils, leaving extensive areas of the soil dry even after substantial rainfall. Future climate scenarios will likely enhance the development and persistence of SWR. Despite this, the effect of SWR on CO2 efflux upon rewetting has never been tested and remains poorly understood.The aim of this research was to test the hypothesis that SWR suppresses CO2 pulse after rewetting. A field study was conducted in a burnt pine stand in Portugal, before the first natural rainfall event, and in an unburnt grassland in South Wales (UK) during the 2018 European drought. All sites were severely repellent during the field campaigns. Forest fires are known to induce changes in SWR, often increasing its severity and persistence. The study plots were rewetted with water and water mixed with a wetting agent (Revolution®, Aquatrols) to simulate inhibited and non-inhibited infiltration, respectively. CO2 efflux in response to wetting was monitored before and several times after the rewetting event, using the soil gas flux system along with changes in soil water content, infiltration and runoff. The effect of SWR reduced the CO2 pulse after wetting in all sites.In the lab, intact core samples were rewetted following the same methodology used in the field to simulate wettable and water-repellent conditions. CO2 efflux in response to wetting was continuously monitored using the LI-COR Li-8100A Soil Gas Flux system. Severely reduced infiltration and preferential flow was observed under water-repellent conditions. Typical Birch effect observed under wettable conditions was not detected in water-repellent soils.The main conclusion from the experiment is that the hydrological response of water-repellent soils to wetting have an impact on CO2 fluxes. Hence SWR becomes an important parameter to consider in monitoring and modelling of gas fluxes. Keywords: soil water repellency, hydrophobicity, CO2 efflux, CO2 pulse, Birch effect, wildfires, forest fires. [ABSTRACT FROM AUTHOR]

Tenerife (2034 km2), the largest island of the Canarian archipelago, hosts three volcanic rifts and a central volcanic complex, Las Cañadas, which is characterized by eruptions of differentiated magmas. Lying inside Las Cañadas and at the intersection of the three volcanic rifts, a twin stratovolcano system, Pico Viejo-Teide, has been developed. Teide summit cone has been constructed during several phases and, although it shows a weak fumarolic system, volcanic gas emissions observed there are mainly controlled by high rates of diffuse CO2 degassing all around the summit cone of Teide (Pérez et al., 2013). During summer 2018, 14 soil gas surveys have been performed at the summit crater of Teide volcano to determine the diffuse He and H2 emission rates and to evaluate the temporal variations and their relationships with the seismic–volcanic activity. In each survey a total number of 38 sites were sampled homogeneously distributed within an area of 6,972 m2 inside the summit crater. Soil gases were sampled at 40 cm depth using a metallic probe with a 60 cc hypodermic syringe and stored in 10 cc glass vials for later laboratory analysis. Diffusive and convective emission components of He and H2 were estimated at each sampling site following the Fick and Darcy's laws, respectively. In order to compute the diffuse He and H2 emissions at the studied area, spatial distribution maps were constructed using sequential Gaussian simulations. The zones with the highest diffuse He and H2 emission were also characterized by high CO2 effluxes and relatively high soil temperature (>60 ̊C) as well as intense hydrothermal alteration. Temporal evolution shows a range from 0.03 to 4.1 kg•d-1 and from 5.2 to 15 kg•d-1, with an average values of 0.5 kg•d-1 and 9 kg d-1 for He and H2, respectively, with maximum values measured on June 13th survey. The observed increases on both gases are well-correlated with an increase in the seismic activity recorded during 2018. INVOLCAN seismic network registered a total of 114, 175 and 67 seismic events for April, May and June, respectively. These changes in the He and H2 emission rates were probably due to the increase of fluid pressure in the hydrothermal-magmatic system of Tenerife. Periodic diffuse He and H2 emission surveys will be a valuable to improve and optimize the detection of early warning signals of future volcanic unrest at Teide volcano.ReferencesPérez et al., 2013. J. Geol. Soc., DOI: 10.1144/jgs2012-125. [ABSTRACT FROM AUTHOR]

NOx is a main precursor for tropospheric O3 and a key substance determining the oxidativecapacity of the atmosphere. Soil NO emissions, contributing 15-20% to the globalatmospheric NOx budget (IPCC, 2007), are the result of biogenic, mostly microbial,biochemical and physicochemical N cycling processes. It is known that NO emissions fromsoils are the result of simultaneously occurring production and consumption processes.Several studies showed that NO emitted from soils mainly originate from the topmostcentimetres and that NO produced in deeper soil layers might be consumed during upwarddiffusion. However, information on NO concentrations and profiles of NO concentrations insoils is extremely scarce and to our knowledge limited to the works of Gut et al. (1998, 1999,2002). In this study we carried out continuous measurement of NO concentrations over oneentire year along a soil depth profile down to approx. 1m. Measurements were done at aspruce forest site in Southern Germany, the Höglwald Forest, exposed to high rates ofatmospheric N deposition. Soil gas concentrations of NO were continuously measured at fivesoil depths using gas permeable tubes. Those measurements were accompaniedby continuous soil-atmosphere NO flux measurements using a dynamic chamberapproach. The highest soil NO concentrations, as well as soil surface NO fluxes, were observedduring summer times, specifically following rainfall events, which were re-wetting atleast the surface soil. Mean NO concentrations from soil surface down to -65 cmdiffered significantly and ranked as follows: 142 ± 2.1 ppbv in the litter layer (-5 cmbelow soil surface) > 112.2 ± 1.7 ppbv in the mineral topsoil Aeh layer (-12 cm) >96.1 ± 1.3 ppbv in moss layer (0 cm; on soil surface) > 27.9 ± 0.3 ppbv in themineral Al layer (-30 cm) > 11.4 ± 0.1 ppbv in subsoil Bt layer (-65 cm soil depth).While mean ground level air NO concentration was 4.1 ± 0.1 ppbv. The annualmean emission observed within the study period was 63.0 ± 0.6 μg NO-N m−2h−1. In this presentation we will present a modified system for soil NO gas monitoring, themain results (incl. the very first continuous data on NO concentration in soil profile), evaluatedrivers for NO production/ consumption in the soil, as well as provide hypotheses about theimportance of NO production/ consumption processes as drivers of soil microbial and plantprocesses. So far it can be said that: i) the most effective depth of NO production at the studied forest site was around 5 cm(within the organic layer); ii) temperature was determined as the main driver triggering NO production within thesoil and NO emission from the soil; iii) annual NO concentration level across the soil profile was strongly depending on soilpH; iv) strong dependence between soil NO emission rate and NO concentrations on thesurface and in organic layer was clearly shown; v) observed soil NO concentrations are high and at those concentrations effects on rootgrowth and root distribution have been observed. [ABSTRACT FROM AUTHOR]

Madeira is an intraplate volcanic island, located in the eastern North Atlantic Ocean, 500 km north of the Canaries. It is a topographically very heterogeneous island, with an emerged area of 737 km2. Madeira lies in a region of low seismicity rate (<40 events/yr) with events of low to moderate magnitudes (ML <4.0). Madeira figures in the list of worldwide hotspots since favored the existence of a mantle plume to explain hotspot volcanism in the region (Matos et al., 2015). Although no historical eruptions are documented, last subaerial eruption took place about 6,000 years ago. With the aim of providing a multidisciplinary volcano monitoring program for Madeira in the framework of the project, VOLRISKMAC (MAC/3.5b/124), a soil gas degassing survey was carried out carried out first time in May 2018, covering an area of 257 km2 located at the central sector of the island with a total of 472 sampling observation sites. The accumulation chamber method was used to perform soil CO2 efflux measurements at each sampling site by means of a portable non dispersive CO2 sensor, model LICOR-Li-820. Soil temperature at 15 and 30 cm depth was also measured in situ, whereas soil gases at each sampling point were collected by means of a stainless steel probe inserted 40 cm depth in the soil for further chemical and isotopic analysis in the laboratory. In order to investigate the spatial distribution of each geochemical parameter as well as to estimate the diffuse emission rates for CO2, He, and H2, maps were constructed following sequential Gaussian simulation. Diffuse CO2 emission values ranged between non detectable values to 104 g•m-2•d-1, with an average value of 9.4 g•m-2•d-1. Highest soil CO2 efflux values were measured at the SW and NE sectors of the studied area. Estimated diffuse CO2 emission rate for the studied area was 2,292 ± 8 t•d-1. The CO2 isotopic composition (mean value -21.7‰) indicated that most of the sampling sites exhibited CO2 composed by different mixing degrees between atmospheric and biogenic CO2 with slight inputs of deep-seated CO2. Regarding to He and H2, and assuming a pure diffusive mechanism, diffuse emission rates were estimated on 25 ± 1 kg•d-1 and 57 ± 2 kg•d-1, respectively. Most of the study area showed low He diffusive flux values, although an anomalous zone located to the east of the study area is clearly differentiated with measured values higher than 400 microg m-2•d-1. This area coincides with an anomaly of low S wave seismic velocity with an approximately circular shape, obtained through a seismic tomography study to investigate the upper cortical structure of the island of Madeira (Matos et al., 2015). On the other hand, spatial distribution of H2 emission values did not show a clear connection with main volcano-structures of the island. This work demonstrates the importance of performing diffuse emission studies as a promising volcano monitoring technique that might help to detect early warning signals of volcanic unrest in oceanic volcanic islands.Matos C., et al 2015. J. Volcanol. Geoterm. Res. DOI: org/10.1016/j.jvolgeores.2015.03.017. [ABSTRACT FROM AUTHOR]

Soil organic matter (SOM) is a key ecosystem and societal resource, as it stores large amounts of carbon while regulating soil nutrient availability and water holding capacity. Despite its clear importance, we still have relatively poor ability to understand and forecast SOM dynamics. In particular, we need to understand the timescales associated with different mechanisms of C stabilization and how those can be altered by climate change. Radiocarbon is the most powerful tool we have for assigning timescales to soil C cycling. In open systems like soils, the degree to which radioactive decay of radiocarbon has occurred in SOM reflects the time it has been isolated from exchange with the atmosphere over hundreds to tens of thousands of years. Fractionating SOM with different chemical or physical methods can help link those longer timescales of stabilization to specific mechanisms. The radiocarbon content of microbially respired carbon dioxide can give information on the age of carbon being returned to the atmosphere – a measure of the time it takes for C to transit the soil system. All of these measures can be predicted by global carbon cycle models as well as measured directly, meaning that radiocarbon provides important constraints on our understanding of soil carbon cycling. For example, a recent comparison of synthesized bulk soil radiocarbon data with model estimates of SOC age (He et al., 2016, Science 353: 1419-1424) indicated that models from the coupled model intercomparison project 5 (CMIP5) overestimated the mean radiocarbon content and thus underestimated the mean age of SOM to a meter depth and demonstrated that this leads to model overestimation of SOC sequestration potential. Despite the importance of radiocarbon as a constraint for soil C cycling, and recent increases in the number of papers reporting radiocarbon data, efforts to synthesize these data globally have been limited to bulk soil radiocarbon measurements. ISRaD, the International Soil Radiocarbon Database, is intended to be an open source platform for synthesizing the diverse array of soil radiocarbon data available and a destination repository for future radiocarbon analyses. ISRaD is built on previous work by Mathieu et al. (2015, Global Change Biology 21: 4278-4292) and He et al (2016), and adds new information on soil fractions, fluxes, incubations, and interstitial measurements from soil water and gases. Currently, ISRaD includes data compiled from nearly 200 individual studies spanning over 400 locations across the globe. While ISRaD is already a useful tool for compiling and analyzing radiocarbon data from a wide range of sample types and measurement locations, the full potential of this resource will be realized through participation in the continued development and management by the broader scientific community. [ABSTRACT FROM AUTHOR]

Furnas Volcano, a stratovolcano with maximum height about 800 m a.s.l, occupies the east-central part of São Miguel Island, Azores archipelago (Portugal) and has experienced 17 trachytic eruptions during the last 5,000 years, including 10 eruptions within the inner caldera, being the last one subplinian with the formation of a tuff ring and dome. Main fumarolic fields are located in the northern shore of Lagoa das Furnas and in Furnas village area, and seem to be mostly associated with the WNW-ESE and NW-SE tectonic structures that cross the volcano edifice. However, non-visible (diffuse) emission is currently the main emission mechanism of volcanic gases at the scale of the entire volcano (Viveiros et al., 2010; Pedone et al., 2015; Andrade et al., 2016). In this work, we present the first study of He and H2 emissions, with the aim to provide additional insights of the degassing regime of Furnas Volcano. H2 and He are highly mobile and/or non-reactive gases that offer important advantages for the detection of vertical permeability structures, because their interaction with the surrounding rocks or fluids during the ascent toward the surface is minimum. He has unique characteristics as a geochemical tracer: it is chemically inert and radioactively stable, non-biogenic, highly mobile, and relatively insoluble in water. H2 is one of the most abundant trace species in volcano-hydrothermal systems and is a key participant in many redox reactions occurring in the hydrothermal reservoir gas. In May 2018, 272 sampling sites were selected covering homogenously the soils of Furnas caldera. At each sampling site soil gas samples were taken at 40 cm depth and analyzed later in the laboratory for the He and H2 content. To estimate the He and H2 emission rates at each sampling point, the diffusive component was estimated following the Fick's law and the convective emission component model was estimated following the Darcy's law. Diffuse He and H2ranged from non-detected values and 15 and 985 mg m-2 d-1, respectively. The spatial distribution maps, constructed averaging results of the 100 simulations following the sequential Gaussian simulation algorithm, He and H2 degassing anomalies mainly located at those areas with surface geothermal manifestations. The He and H2 emission rates were estimated 1.3 kg•d-1 and 36 kg•d-1, respectively. The multi-gas evaluation of these silent, invisible soil emission rates and their ratios may be an important tool for the volcanic surveillance program of Furnas Volcano, since soil degassing is the biggest volcanic gas emission contributor during the actual quiescent state of the volcano.References:Andrade et al., 2016. J. Volcanol. Geotherm. Res. 315:51–64.Pedone et al., 2015. Earth, Planets and Space 67:174.Viveiros et al., 2010. J. Geophys. Res. 115, B12208. [ABSTRACT FROM AUTHOR]

A correct quantification of mass and energy exchange processes among Earth's land surface, groundwater and atmosphere requires an accurate parameterization of soil hydraulic properties. Pedotransfer functions (PTFs) are useful in this regard because they estimate these otherwise difficult to obtain characteristics using texture and other ubiquitous soils data. In this presentation, we first present our recent work that improved a widely used Rosetta PTF model (Rosetta3) that unifies the water retention and saturated hydraulic conductivity (Ks) submodels into one and utilizes parameter uncertainty of the fit of the water retention curve to the original retention data in the calibration procedure. Most PTFs estimate parameters of empirical hydraulic functions with modest accuracy. We developed a PTF that estimates the parameters of the Kosugi functions (Kosugi 1994, 1996), which explicitly assume a lognormal pore size distribution and apply the Young-Laplace equation to derive a corresponding pressure head distribution. Using a combination of machine learning and bootstrapping, we developed five hierarchical models that allow for estimates under practical data-poor to data-rich conditions. Using an independent global dataset containing nearly 50,000 samples (118,000 retention points) we demonstrated that the new PTF outperformed two van Genuchten-based PTFs calibrated on the same data. The PTF was applied to a 1×1 km2 map of texture and bulk density, thus producing maps of the parameters, field capacity, wilting point, plant available water, and associated uncertainties. Finally, 13 widely used PTFs were grouped according to input data requirements and evaluated against independent global dataset. Weighted ensembles were shown to have improved performance over individual PTFs in terms of root mean square error and other model selection criteria. Global maps of soil water retention data from the ensemble models as well as their uncertainty were provided. Our full 13-member ensemble model provides more accurate estimates than PTFs that are currently being used in earth system models. [ABSTRACT FROM AUTHOR]

The Canary Islands, owing to their recent volcanism, are the only Spanish territory with potential high enthalpy geothermal resources. Tenerife (2058 km2, 3718 masl) is the largest of the seven islands of the Canarian archipelago located off the west coast of North Africa and shows evident geothermal surface manifestations (Teide volcano fumaroles, the only visible discharge of geothermal fluids existing nowadays in the Canary Islands). Between 2011 and 2014, preliminary geochemistry and magnetotellurics surveys were carried out in the southern volcanic rift zone of Tenerife for geothermal exploration purposes. After the observed geochemical anomalies at the soil surface, the prominent low-resistivity structure interpreted as a clay alteration cap, and the positive correlation between thickness of clay alteration cap and helium emission and other positive results, it was decided to perform a detail diffuse CO2 emission survey during July-August, 2018 at northern part of the study area where some geochemical and geophysical anomalies were observed. During this survey, 362 sampling sites, with an average distance between sites of ≈ 40 m, were selected along 0.7 km2 area. Soil gases were sampled at ≈ 40 cm depth using a metallic probe with a 60 cc hypodermic syringes and stored in 10 cc glass vials for later laboratory analysis. Soil CO2 concentrations measured ranged from typical atmospheric values (≈ 400 ppm) up to 15200 ppm. The mean value measured for CO2 concentration was 2400 ppm. The CO2 isotopic composition, expressed as δ13C-CO2 showed the contribution of three different end-members: biogenic, atmospheric and deep-seated CO2, defined by isotopic compositions of -24, -8 and -3 ‰ vs. VPDB, and CO2 concentration of 100%, 0.04% and 100% respectively. The results indicate that most of the sampling sites exhibited CO2 composed by different mixtures between atmospheric and biogenic CO2 with slight inputs of deep-seated CO2, with a mean value of -17.1‰, being the maximum and the minimum -3.6‰ and -24.1‰ respectively. The accumulation chamber method (Parkinson, 1981) was used to perform soil CO2 efflux measurements at each sampling site by means of a portable non dispersive CO2 sensor, model LICOR-Li-820. Relatively low CO2 efflux values were measured ranging from non detected up to 55.4 g m-2•d-1, with an average value of 4.2 g m-2•d-1. The highest CO2 efflux values were measured as multiple isolated anomalies, where it was not observed significant trends in the diffuse CO2 efflux anomalies distribution. To estimate the total diffuse CO2 output released from the study area, the average of 100 sequential Gaussian simulations was considered, giving a value of 2.37 ± 0.07 t d-1, which represent a normalized emission rate of 3.4 t km-2•d-1vs. 1.9 t km-2•d-1 for the previous study area of 2014. The results showed here can help to identify the possible existence of permeable portions of deep-seated actively degassing geothermal reservoirs, particularly where the interpretation and application of geophysical data is difficult. [ABSTRACT FROM AUTHOR]

The Canary Islands archipelago is located 100 km away from the African North-West coast. It is composed of seven islands, which are distributed from East to West and they are different in shape and composition. However, the archipelago clearly presents magmatic features which begun in the early Tertiary period. The volcanism of the Canary Islands is characterized by alkaline sodium magmatism, subsaturated in SiO2. It is usual feature the presence of rocks of intermediate composition like Trachites and Phonolites, not frequent in oceanic islands. Tenerife, which is extended ≈ 2000 km2 long and 3718 m height over the sea level, is the biggest island within the archipelago. This island shows evident geothermal surface manifestations (Teide volcano fumaroles), where gas composition indicates that steam derives from a mature liquid dominated geothermal reservoir with temperatures in the range of 250-300ºC. But with the exception of the Teide volcano fumaroles, there is not any evidence of hydrothermal fluid discharges in the surficial environment of the Canary Islands, which becomes diffuse degassing surveys an important geochemical tool for geothermal exploration purposes. In the early 2000s, several geochemical and geophysical studies were carried out in different promising areas of Tenerife. The present study shows the results of an intensive detail soil gas helium (He) and hydrogen (H2) survey develop in a specific area of the south of the island where some geochemical anomalies matched with a thinning of the 'clay alteration cap' detected with MT campaigns, since diffuse He and H2 degassing have been previous applied to reveal hidden geothermal resources (Rodríguez et al. 2015). Soil gas samples were collected at 362 sites selected with a homogeneous spatial distribution in the study area (0.7 km2) from July to August 2018, with an average distance between sites of ≈ 40 m. At each sampling site, soil gas samples were collected at 40 cm depth using a metallic probe with a 60 cc hypodermic syringe and stored in 10 cc glass vials for later laboratory analysis. The soil He concentrations were analyzed by means of a quadrupole mass spectrometer (QMS; Pfeiffer Omnistar 422) and the soil H2 concentrations by a micro-gas chromatograph (microGC; VARIAN CP4900). In the case of helium, values are given using the ∆He notation: [∆He = [He]soil atmosphere – [He]air = 5240 ppb]. ∆He values measured on the soil atmosphere ranged from typical atmospheric values up to 20460 ppb, with an average of 805 ppb. Soil H2 concentrations measured ranged from typical atmospheric values (≈ 0.5 ppm) up to 13.22 ppm with an average value of 0.9 ppm. The main ∆He anomalies were located at the south sectors of the study area and H2 concentration showed up as multiple isolated anomalies. The soil He and H2 degassing surveys are a great tool in the first step of the reconnaissance phase and delimitation of geothermal reservoirs in order to take an advance in the understanding of geothermal resources that might exist in the subsurface.References:Rodríguez et al., 2015. Surv Geophys, 36(3 [ABSTRACT FROM AUTHOR]

At fair weather conditions, atmospheric electricity of interesting magnitudes has been observed in Hessdalen, Norway.In this area, transient luminous phenomena have been observed in the low atmosphere for several decades. Light balls of different shapes and color, with a life time from seconds up to two hours have been reported. Electrical field mills have been utilized to measure the static electrical field in the low atmosphere at two mountain tops, Skarvan at an altitude of 975 m and Finså at 1040 m. These mountains is spaced 5.5 km apart along a north-south axis. Data from September 2017 and October 2018 will be presented. A buildup of static charge of more than 15 kV/m is detected under fair weather conditions while the voltage difference between the two mountain tops exceed 20 kV/m. In this area, NGU, the national institution for the study of bedrock, mineral resources, surficial deposits and groundwater, warns for high levels of Radon. Radioactivity data from both mountain tops will therefore also be presented. [ABSTRACT FROM AUTHOR]

Increasing renewable energy production can result in energy storage requirements on variousscales given the fluctuating availability of renewable sources. Power-to-Gas in combinationwith underground gas storage in porous media is a viable option for mitigating offsetsbetween energy demand and availability. Leakage of stored gas along fault zones couldhinder or prohibit storage development, requiring a quantification of potential leakagescenarios. This study investigates the sensitivity of fault zone geometry, petrophysicalparameters and capillary pressures on leakage rates during a gas storage operation usingnumerical scenario simulations. A structural model of an anticline structure in the North German Basin is used for thisanalysis, which spans from Permian up to Quaternary horizons and includes several faultsystems. For the sensitivity analysis, a 2D-slice perpendicular to the main N-Sstriking fault system is selected. In this model, the fault zone is represented as twoindependent units, namely a fault core and a damage zone. Literature analysis indicate thatthe highly fractured damage zone has high absolute permeability and thickness,while the fault core has a low permeability in is reasonably tight. East of the faultzone the storage reservoir is saturated with methane, with reservoir pressures setaccording to a gradient of 15 MPa/km, translating to an absolute pressure at thefault interface of around 86 bars. The remaining formations are set to hydrostaticpressure conditions. Petrophysical parameters, such as permeability and porosity areassumed homogeneous and isotropic. The leakage rates through the fault zone aredetermined for variable fault zone thicknesses (100; 50; 10; 1 m), damage zonepermeabilities (10; 5; 1; 0.01 mD) and capillary entry pressures (varying from 0 to 9.6bars). Results of the simulation with varying fault zone parameters show a strong influence onthe reservoir pressure decline and gas leakage rates. In the worst-case scenario, i.e. assuminga highly permeable damage zone, the gas leakage rate upwards through the damage zonequickly reaches 9000 sm3/d and remains constant afterwards. After about 1 year, gasbreakthrough is observed at the fault core, with leakage rates reaching 500 sm3/d after 2years. Leakage gas volume is 7879678 sm3 after 2 years, which corresponds to 2.26 % oftotal gas in place. At a fault zone with thickness of 100 m, reservoir pressure declines by 14bars compared to the initial condition. In comparison, reservoir pressure declines by around 5bars due to pressure redistribution within the storage formation if the fault zone is assumed tobe completely tight. Cases with different capillary entry pressure do not show a cleartrend, but methane leakage volume can reach up to 6837049 sm3 when capillaryentry pressure is 3.2 bars. The results indicate that significant leakage rates canoccur, showing the sensitivity of storage model to the fault zone parametrization. [ABSTRACT FROM AUTHOR]

The volatile organic compounds (VOCs) in soils stem from a large variety of different sources within soils as soils act as both sources and sinks for these compounds. Many of the VOCs formed in soils are produced by soil microorganisms living within them. There have been many efforts to fingerprint the VOC profiles from these complex microbial habitats, most of which are based on the use of solid phase microextraction (SPME). This automated extraction method allows the monitoring of the community structure, physiological state, and activity of any microbial community in a soil without the need of manual extraction or cultivation procedures.SPME is a fast, economical and solvent-free methodology widely used for the environmental analysis of soils in combination with GC-MS. The methodology using SPME in headspace (HS-SPME) analysis has been used to determine VOCs in a wide range of different soils of varying textures, organic matrices from manures and composts from different origins.In this presentation we discuss an innovative mode of extending the sensitivity of SPME extraction called SPME-trap in which a refocussing cold trap is used to further pre-concentrate analytes released from a SPME fibre used on soil samples before the analytes are injected into the GC-MS system. Other techniques commonly used to monitor the VOC fingerprints from soils are static headspace, headspace- or immersive- high capacity sorptive extraction or thermal desorption using sorbent-packed tubes for active or passive, in situ sampling of soil. The focusing trap technology used in this study allows the combination of all these techniques to be run on a single analytical system without the change of hardware; it also allows single and multiple extractions to be carried out automatically on a single sample to increase the analytical sensitivity, thus achieving a comprehensive VOC profile. To illustrate the enhanced capabilities of SPME-trap we investigate the fingerprints of VOCs for a 50 cm soil profile of a loamy and clayey floodplain soils with naturally high groundwater around Llantrisant, UK with a variety of different VOC sample preparation methods showing the benefits of adding high-performance trapping technology to the VOC analysis of soils. [ABSTRACT FROM AUTHOR]

We monitored the Sulfur hexafluoride (SF6) concentration in the air, the spring and thegroundwater to estimate the residence time of the water from April 2015 through May 2018at a small forested headwater catchment underlain by granite in Fukushima, Japan. The SF6concentration in the air ranged from 9.2 pptv to 14 pptv, and it temporally increased with agradient of 0.5 pptv/year. Also, the SF6 concentration in the spring water ranged from 3.5 fmol/L to 4.6fmol/L during this period, corresponding to the concentration ranging from 9.9pptv to 12.8 pptv in the air with increasing rate of 0.4 pptv/year based on Henry&#x2019;sequilibrium law between the air and the water. Thus, the temporal change of SF6concentration in the spring water shows the same trend as that of the air in thewatershed with a time lag of a few years. In addition, the apparent SF6 age in the springranged from 2 years to 7 years in the base flow condition except for the rainfall eventperiods. Therefore, the time lag of the temporal change in the SF6 concentrationbetween the air and the spring agrees well with the apparent SF6 age in the springwater. Consequently, these results show that the groundwater flow in the watershedcould be represented displacement piston flow model, and the temporal changepattern of SF6 concentration in the air is conserved well in the groundwater withinthe watershed. Also, the SF6 has a temporal information as two aspects, one isapparent age and the other is conservative temporal pattern such as stable isotopes. [ABSTRACT FROM AUTHOR]

Soil microsites where newly added plant residue undergoes decomposition are the hotspots ofmicrobial activity, due to microbial utilization of organic matter as their energy sources. Thusthose sites often contribute to high emission of greenhouse gases such as carbon dioxide(CO2) and nitrous oxide (N2O). Although it is known that microbial activity anddecomposition are regulated by residue&#x2019;s chemistry, residue&#x2019;s interactions with soil physicalcharacteristics have been less understood. Specifically, soil pore size distributions could alsoalter the degree/type of microbial activity by regulating soil water and air pathways, includingO2 levels. In the past most of the plant residue incorporation studies focused onagronomic crops, while the crops that are currently proposed as feedstock for bioenergyproduction received less attention. For example, switchgrass is considered as one of thesustainable bio-energy crops due to its high yield, low input, and positive impact on soiland water conservation during the growth. Studying decomposition of switchgrasswould allow us to assess its environmental impact more thoroughly. Thus, the goalof this study is to: 1) investigate the rate of decomposition for switchgrass leafand root residues incorporated into soil with contrasting pore characteristics; 2)monitor CO2 and N2O fluxes from the soil with incorporated residue during thedecomposition; and 3) monitor O2 levels and spatial patterns of extracellular enzymes duringdecomposition. We built soil microcosms (d = 8 mm) with 2 g of soil and 2 mg of residue using soilmaterials with contrasting pore size distributions, namely with prevalence of &#x003C; 10 um and &#x003E;30 um pores. CO2 and N2O emission rates were measured during 21-day incubation, andcomputed micro-tomography was used to quantify residue decomposition at 7, 14, and 21days of incubation and moisture redistribution after the incorporation of plant residues.Additionally, oxygen micro-sensors and zymography technique will be applied to examinethe O2 and enzyme distributions (ongoing). Preliminary results showed that overall CO2 and N2O emissions were greater in soil withprevalence of &#x003C; 10 um pores rather than &#x003E; 30 um pores. However, presence of residues led togreater increases in N2O emissions from the soil with prevalence of &#x003E; 30 um pores than inthat with &#x003C;10 um pores. The increases of CO2 emissions due to the residue inputswere not significantly different among the two pore size treatments. The peak N2Oemission in control soil was reached on day 1, but peak emissions occurred onday 3-5 in the presence of residues. Greater residue decomposition took place inthe soil of &#x003E; 30 um than in &#x003C;10 um pore treatments. There were no significantdifferences in CO2 / N2O emissions between switchgrass root and leaf residues. [ABSTRACT FROM AUTHOR]

Florina Basin is located in northern Greece, close to Mount Voras where the volcanic activityof Late Messinian age began. In the area, many CO2-rich gas emissions are present as abubbling free-phase in groundwater (both springs and wells) and soil gases. Volcanismalong with the geological and geodynamic regime of the basin, created the idealconditions for CO2 accumulation in vertically stacked reservoirs. One of these,industrially exploited by the company Air Liquide Greece, produces 30,000 t/a ofCO2. Results show that CO2 concentrations in the gases of Florina can arrive up to99.8% and are mostly above 90%. Moreover, C-isotope composition (-2.1 to + 0.3‰ vs. VPDB) indicates a mixed mantle-limestone origin for CO2, while He isotopecomposition (R/RA from 0.21 to 1.20) shows a prevailing crustal origin with an up to 15%mantle contribution. Helium and methane, with concentrations spanning over threeorders of magnitude, show a positive correlation and a consequent high variability ofHe/CO2 and CH4/CO2 ratios. This variability can be attributed to the interaction of theuprising gases with groundwater that chemically fractionates them due to theirdifferent solubility. Based on the CO2, CH4 and He concentrations, gas samplescollected in the basin can be divided in 3 groups: a) deep reservoir gases, b) enriched inless soluble gases and c) depleted in less soluble gases. The first group consists ofgas samples collected at the Air Liquide extraction wells, which tap a 300m deepreservoir. This group can be considered as the least affected by fractionation processesdue to interaction with groundwater. The gases of the second group due to theirinteraction with shallower unsaturated aquifers, become progressively enriched inless soluble gases (He and CH4). Finally, the third group represents residual gasphases after extensive degassing of the groundwater during its hydrological pathway. [ABSTRACT FROM AUTHOR]

The new monitoring system based on Internet of things technology can provide advanced and complete capacity for wide range and sustainable field monitoring data acquisition and sharing. This paper introduces the application of the ecological monitoring IoT network of Heihe River Basin. By adopting a series of new monitoring equipment based on the technology of Internet of things, the monitoring of the key parameters of water, soil and air in the area of Heihe River Basin is realized. At the same time, combined with the technology of Data Automatic Assembling, through the unified remote data receiving module, data preprocessing module, automatic warehouse module, relational database system, and the online visual monitoring data management application platform, the efficient remote monitoring network and monitoring data application system can be formed, which can effectively improve the monitoring capability and the real-time and availability of monitoring data.As a application example, an application system was developed for the ecological monitoring IoT network of Heihe River Basin. The observation data gotten from the remote data collector would be collected, preprocessed, evaluated, and shared full automatically.The uploaded data first passed through the data interface. The function of the data interface is to normalize the raw data, which would come from different kinds of instruments, in a normalized way automatically. Then the raw data and the format-normalized data are putted into a specially designed relational observation database. All acquired data was saved in a relational database. Users can access the data via a mobile terminal or computer remotely. [ABSTRACT FROM AUTHOR]

Soil respiration is one of the most significant carbon fluxes in terrestrial ecosystems. Since different sources of soil respiration might respond differently to climate change it is necessary to separate underlying processes. Several methods have been suggested to separate root respiration and heterotrophic respiration in soils. The most promising approach is based on isotopic signature of CO2 (δ13C).We measured the temporal variability as well as vertical and horizontal gradients of soil CO2 in a pine forest ecosystem (ICP Forests plot DE1203) over the entire vegetation period of 2018. Further-more, the isotopic signature of CO2 (δ13C) was detected in order to evaluate the potential for separating autotrophic and heterotrophic shares of soil respiration. Soil gas samples were collected every 80 minutes using gas permeable polypropylene gas probes and measured using Cavity Ring Down Spectroscopy. The forest ecosystem is dominated by mature Scots pine trees (Pinus sylvestris) and a dense ground vegetation of blueberry (Vaccinium myrtillus L.) and moss (Scleropodium purum (Hedw.) Limpr.]). Soil type is Haplic Podsol from medium-coarse sand.Results provided clear correlations of CO2 concentrations and its δ13C signature with meteorological conditions and spatial gradients. CO2 concentrations increased following rain events, but δ13C val-ues decreased. Diel variation showed minimum CO2 concentrations with maximum δ13C values at noontime. Amplitudes of temporal effects decreased and were postponed with increasing soil depth. CO2 concentration increased with soil depth, but δ13C values decreased. In a spatial gradient from in between trunk area towards a single trunk CO2 increased, but δ13C values decreased, which might be caused by varying root density. It is a challenge to clarify these interactions - our approach delivers a basis already proven to reveal temporal and spatial variability of soil CO2 and its isotopic signature under site conditions. [ABSTRACT FROM AUTHOR]

In boreal and arctic ecosystems, mosses (bryophytes) forms ground cover that stretches from upland forests to peatlands being ubiquitous component of plant communities. The bryophyte cover in boreal landscape forms a biologically active boundary between the atmosphere and soil having an influence on the nutrient, carbon and water cycling as well as the energy balance at the ground surface. The presence of moss cover on soil surface is known to significantly mediate soil moisture, reduce diurnal and annual temperature amplitudes and active layer depth. It is much less known how diversity of bryophyte species and communities affect coupled surface energy and water balances. It is widely accepted that when exposed to given environmental conditions, the variations in energy, water and carbon exchange rates among bryophytes are related their physical and structural properties.With the modelling, it is possible to study biogeochemical feedbacks between canopy and soil between different environments. Water, energy and carbon balances in boreal ecosystems were studied by using a 1-dimensional multilayer, multispecies soil-vegetation-atmosphere transfer model APES (Atmosphere-Plant Exchange Simulator) with separate bryophyte layer. The model was applied in environmental gradients found in boreal landscape to study effect of bryophyte properties in different ecosystems. In the study, the effect of two types of bryophytes on water and energy balances were investigated, feather and sphagnum mosses. The two groups grow on different light and moisture conditions having distinctive photosynthetic and water holding properties. In the study we identify the key functional traits of both groups that are important in different environments with same meteorological conditions.Environmental gradients covered changes in canopy structure and soil characteristics (mineral and peat soils). Change in canopy structure (from open canopy to dense) have an effect on microclimate, especially on light conditions in both environments, forests and peatlands. Change in soil characteristics forms a hydrological gradient from well drained mineral soil to water logged peat soil. [ABSTRACT FROM AUTHOR]

In high mountains, the Critical Zone (CZ) is a thin and potentially fragile layer at the borders of life. To study CZ dynamics in such extreme conditions, in 2017 we established a new Critical Zone and Ecosystem Observatory in the high-altitude environment of Pian del Nivolet in the Gran Paradiso National Park (Western Alps, NW Italy), a highly-protected, closed hydrological basin between about 2500 and 2700 meters amsl. This area usually is covered with snow from November to June and much of it hosts alpine pastures. The Pian del Nivolet area is characterized by typical glacial landforms and the bedrock geology consists primarily of orto- and para-gneiss, calcschist, metabasites, marbles and dolostones, variably covered by glacial and alluvial deposits.Here we explore and discuss whether and how CO2 fluxes are modulated by the characteristics of the underlying bedrock and by the soil physical and chemical conditions (temperature, humidity and TOC). To this end, four study plots have been selected on the basis of the main geological and geomorphological features of the area. CO2 fluxes at the soil-atmosphere interface (respiration and net ecosystem CO2 exchange) were measured by a portable accumulation chamber. Measurements were performed during the day in light and dark conditions, in order to estimate CO2 absorption due to photosynthesis and CO2 emissions due to soil activity and root respiration. A total of 10 surveys from July to October 2017 and 2018 were carried out, with more than 25 individual replicas for each plot (covering about 250 m-2) during each survey. Statistical tests were then performed to assess the significance of the observed variability inside each plot and across plots, using multiple nonlinear regressions on soil parameters and underlying bedrock characteristics. This work has been done in the framework of the European H2020 project ECOPOTENTIAL (Grant Agreement n. 641762). [ABSTRACT FROM AUTHOR]

Atmospheric continental relative humidity is an important climate parameter poorly constrained in global climate models. A model-data comparison approach, applicable beyond the instrumental period, is essential to progress on this issue. However, there is a lack of proxies allowing quantitative reconstruction of past continental relative humidity. Phytoliths are micrometric amorphous silica particles that form continuously in living plants, and their morphological assemblages recovered from soils and sediments are commonly used as past vegetation indicators. In addition, they precipitate in isotope equilibrium with the plant water, which offers the opportunity of reconstructing leaf water isotope composition. Recently, an experiment in climate chamber demonstrated that relative humidity is a major control on the triple oxygen isotope composition of grass leaf water and phytoliths. However, in order to assess the accuracy of the triple oxygen isotope composition of phytoliths as a humidity proxy, a quantitative understanding of fractionation processes at play in water, at the sol-plant-atmosphere interface, is required. For that purpose, there is a need of direct and continuous measurements of the triple oxygen isotope composition of the atmospheric water vapor surrounding the leaves, a key factor of the isotope 18O and 17O-enrichment in the leaf water due to evaporation (Craig-Gordon model). Here, a new climate chamber was designed to monitor the triple oxygen isotope composition of the different water reservoirs at the soil/plant/atmosphere interface. The chamber allowed to control the oxygen isotope composition of the water vapor.The grass species Festuca arundinacea was grown on soil under different conditions of relative humidity, temperature and partial pressure of CO2. The soil water evaporation was prevented. For each climate condition, leaf water and phytolith oxygen isotope compositions were analyzed by mass spectrometry. The constancy of isotope compositions that were set for irrigation water, soil water, and fogging water were checked by laser spectrometry analysis in liquid mode. Water vapor was continuously measured by laser spectrometry in vapor mode. The triple oxygen isotope composition evolution in the soil/plant/atmosphere continuum is presented and fractionation processes at play are discussed. [ABSTRACT FROM AUTHOR]

Northern ecosystems are crucial to the global carbon cycle because they are rich in organic carbon, which has built up in frozen soils, litter, and peat (Schuur et al., 2008). Although climate change is expected to lead to permafrost thawing and an increase in greenhouse gas fluxes between soils and the atmosphere (Koven et al., 2011), the regulating factors of organic matter decomposition and translocation in the seasonally thawed active layer, however, are insufficiently understood to confidently predict the feedback of thawing permafrost to global warming. The aim of this study was to identify hot spots and leading factors of the spatial distribution of organic and inorganic carbon fluxes on a wetland complex of North West Siberia. The study included a simultaneous measurement of some labile indicators of soils and natural waters, as well as environmental factors for a single small area of palsa and surrounding wetlands (august 2016, 2017, and 2018).The research area is located in the discontinuous permafrost zone in the northern taiga of West Siberia, Russia. Palsa, the object of this study, is 1 m high above the surrounding wetlands and is about 30 m in diameter. It is flat with a slight slope and abrupt edge to the bogs. Typical vegetation is various lichens and mosses, dwarf birch, sedge. The average thickness of peat is 30 cm. The test points were arranged in circles: central, middle, edge of the palsa and wetland (without permafrost) near the palsa.The interannual variability of weather conditions determined the difference in soil temperature, the active layer thickness, and the CO2 efflux. However, all the patterns of spatial distribution of these indicators were identical. The minimum active layer thickness was at the middle part of the peatland, and the maximum was in the center and on the edge. The minimum soil temperatures were observed in the middle part of palsa, in areas with shallow permafrost. In the same part, the minimum values of CO2 efflux from the soil surface and CO2 concentrations in the suprapermafrost layer were also noted. Directly near the edge of the palsa, high values of dissolved organic carbon (DOC) (up to 90 mg/l) and CO2 concentration (headspace equilibration method, up to 17000 ppm) in bog water were recorded. With increasing distance from the palsa CO2 and DOC concentration decreased.We assume that such variations in CO2 flux and DOC concentrations are due to its lateral transport in the soil, especially in the suprapermafrost layer. Thus, the peatland edge is a hot spot of carbon exchange between soil, natural waters and the atmosphere. And the redistribution of carbon flux depends largely on the topography of the permafrost table.This research was supported by the Russian Foundation for Basic Research (Grant 18-04-00952).ReferencesKoven, C.D., Ringeval, B., Friedlingstein, P., et al., 2011. Permafrost carbon-climate feedbacks accelerate global warming. Proceedings of the National Academy of Sciences 108: 14769-14774.Schuur, E.A.G., Bockheim, J., Canadell, J.G. et al., 2008. Vulnerability of permafrost carbon to climate change: implications for the global carbon cycle. BioScience 58(8): 701-714. [ABSTRACT FROM AUTHOR]

Studies on soil greenhouse gas (GHG) fluxes from tropical grassland soils are limited compared to temperate climates. While multiple studies evaluate GHG emissions from tropical forest soils, studies from grassland soils are very rare. In this study, we measured soil greenhouse gas fluxes (CO2, CH4 and N2O) from two experimental sites in Singapore over one year. The sites were located at Bishan-Ang Mo Kio Park (urban grassland) and MacRitchie Reservoir Park (natural forest). GHG emissions from different management practices in urban grassland were evaluated by comparing untreated grassland soil (T1), compost amended soil (T2) and soil with N2-fixing plants as ground cover (T3). Furthermore, mineral N, microbial biomass C and N, TOC and TN content of soil, litter and grass biomass were analyzed. Preliminary results indicated that untreated urban grassland and compost amended soils acted as sources for CO2, CH4 and N2O with T2 having the highest global warming potential. Parkland soils covered with N2-fixing plants acted as both source and sink for CH4 and N2O. Forest soils were also found to emit more N2O but less CO2 compared to urban grasslands soils. Furthermore, it was found to be a sink for CH4. Detailed results and GHG budgets will be presented. [ABSTRACT FROM AUTHOR]

Favorable hydrological properties combined with periodic input of organic matter and nutrients after flooding dispose floodplain forests as potential hot spots of carbon (C) and nitrogen (N) cycling. Environmental conditions could also be favorable for the production of nitrous oxide (N2O) and methane (CH4). We have measured soil N2O and CH4 fluxes at 18 sites in the Danube National Park (~ 10.000 ha), spanning natural gradients from frequently to less frequently flooded forest, from 2017 until 2019. Three intensive monitoring sites were additionally equipped with auto-chambers to measure soil greenhouse gas fluxes in daily resolution. Starting in 2018, stem N2O and CH4 fluxes were measured at the intensive sites as well. Against our expectations, floodplain forest soils acted primarily as CH4 sinks. Though we observed CH4 emissions shortly after flooding, the soil at the frequently flooded sites still showed average CH4 uptake of 18 µg CH4-C m-2 h-1 during the first 18 month of our study. Less frequently flooded sites showed soil CH4 uptake rates of on average 54 µg CH4-C m-2 h-1. Nitrous oxide was mostly emitted from soil and fluxes increased shortly after flooding events (30 – 50 µg N2O-N m-2 h-1). Highest soil N2O emissions (> 70 µg N2O-N m-2 h-1) were, however, measured independently of flooding during freeze-thaw periods in late spring. Tree stems fluxes differed among tree species (poplar, ash) and among stem sampling heights. Poplar showed sharply declining CH4 and N2O emissions with increasing stem measurement height. Ash showed opposite trends with regard to CH4 and no distinctive pattern with regard to N2O. Generally, stems mostly emitted CH4 and N2O, but emissions were very low. [ABSTRACT FROM AUTHOR]

There are several issues surrounding gas flaring and its huge impacts on humans, the environment and the economy. All governments, international institutions and operating companies recognized the gas flaring as a foremost anthropogenic source for greenhouse and/or precursor gases, particulate matter and black carbon that pollute the air, soil and water, at local, regional and global scale as well as a waste of a non-renewable resource. The main challenge faced in the effective characterization of gas flaring is the lack of systematic, complete and reliable data on its magnitude and spatial distribution. Since few decades, satellite data have been exploited to provide independent information on gas flaring activity at global, national and local scale. In particular, the analysis of long series of satellite imagery, with different spatial and spectral resolutions, demonstrated the effective usefulness of these data to recognize flaring affected areas, monitor their evolution both in space and in time, and determine how much emission is released by oil&gas plants at different spatial scales.Among the few techniques developed ad hoc for gas flaring investigation, the RST-FLARE algorithm, based on the processing of multi-year time series of nighttime infrared MODIS data, showed a good level of accuracy and reliability in i) identifying flaring sites, ii) computing the amount of burned associated gas and iii) following their changes over space and time, when applied at both local and national scale.This work is focused on the discussion of the RST-FLARE performances when investigating the gas flaring in the Niger Delta region, one of the top five gas flaring areas in the world, in years 2000-2016. The achievements carried out for this study case are in a very good agreement with independent data, provided by other satellite techniques and national/international organizations, both in terms of flaring sites localization (95% of spatial match) and volume estimates (mean bias between in 16% and 20%, at annual scale and 2–9% in the long period). Outcomes of this work seem to indicate that RST-FLARE can be used to provide, at different geographic scales, quite accurate data on gas flaring, suitable for monitoring purposes for governments and local authorities.Exploiting the RST independence of the investigated signal/sensor, work in progress are focusing on the development of a VIIRS-based RST-FLARE configuration to further improve its ability in quantitatively characterizing flaring sites (e.g., area, temperature, emission power, flared volumes). [ABSTRACT FROM AUTHOR]

Based on plot scale experiments and simulations we develop and parameterize the new Agro-Forest Crop Atmosphere Soil System model (AFCASS) within the ecosystem modelling framework Expert-N that combines tree growth and crop respectively grass growth models assuming three different field areas: (i) tree strip area, (ii) transition area between trees and crop/grass and (iii) crop/grass land area to simulate the complete field scale agro-forestry system.The model structure of the new model is presented and discussed. Simulations include light attenuation and plant internal water flow, leaf photosynthesis, plant growth and nutrient uptake for the three different agroforest areas for which also soil organic matter turnover and specific crop residue management is modelled by using the models SOILN and CENTURY and the Expert-N surface litter turnover model adapted to include tree litter: twigs, branches and specific fruits.The model is parameterized and tested using experimental data obtained by sub-projects of the BONARES SIGNAL Project that investigates agro-forestry systems at five different sites within different regions of Germany. It is the aim to study scenarios to analyse possible impacts of various management options (tree & crop area, tree & crop species, crop rotations, harvesting intervals, exposition) on soil and ecosystem properties (biodiversity, C-sequestration, nitrate leaching, soil erosion, plant water availability). [ABSTRACT FROM AUTHOR]

Northern ecosystems are important components of the global carbon cycle. Nowadays we are observing climate changes in the Arctic that are connected with natural and anthropogenic processes. These processes affect ecosystems, changing their biogeochemical cycles, hydrological regime, structure and functioning. As a result, permafrost degradation occurs and runoff changes.Changes in the quantity and quality of dissolved carbon, which comes from terrestrial ecosystems, have an impact on the carbon balance in the wetlands, as well as influence the carbon balance of the entire catchment. Nowadays we have a restricted understanding of the biogeochemical processes and relationship between terrestrial ecosystems, wetlands and the atmosphere in northern regions of Russia. Therefore we cannot model changes in the chemical composition of surface waters and carbon fluxes.The main aim of this study is to quantify carbon dioxide exchange between terrestrial and aquatic ecosystems a case of study from the wetland complex of Western Siberia. The study area is located in the North of Western Siberia, in the discontinuous permafrost zone: at the northern boundary of the northern taiga subzone. The main objects: palsa bogs, water-filled ditch-like hollows and thermokarst lakes.Concentration of CO2 in waters was directly measured using the "headspace equilibration" method. The essence of the method is to balance the water sample with atmospheric air. Then, the concentration of CO2 in the syringe and in the atmospheric air was measured, and by complex calculations [Halbedel, 2015], the concentration of dissolved carbon dioxide was determined. Gaseous losses from the water surface to the atmosphere (evasion) were determined using the direct floating chamber method. It involves gas emission measurements in the restricted volume of the chamber during a specific time interval. A portable gas analyzer was used for CO2 concentration measurements [Bobrik, 2018]. Concentration of dissolved CO2 (pCO2) varies from 153.1 ppm to 1163.2 ppm in lakes. In palsa bogs CO2 (pCO2) was from 4009.4 ppm to 220322.0 ppm, in water-filled ditch-like hollowsvaries from 12013.2ppm to 241142.9 ppm. Thus, lakes can be sink or small source of carbon dioxide. Palsa bogs are significant sources of carbon, as evidenced by direct evasion data, which is 85.5±25.3mg/m2/hr on the average. These data are comparable with the CO2 emission values from the soil surface of permafrost peatlands 94.0±47.9mg/m2/hr on the average. Water-filled ditch-like hollows also are sources of carbon dioxide.References:• Susanne Halbedel, 2015. Protocol for CO2 sampling in waters by the use of the headspace equilibration technique, based on the simple gas equation; second update. https://www.nature.com/protocolexchange/protocols/4275• A. Bobrik, I. M. Ryzhova, O. Yu. Goncharova, G. V. Matyshak, M. I. Makarov, and D. A. Walker. 2018 CO2 emission and organic carbon pools in soils of the northern taiga ecosystems of Western Siberia under different geocryological conditions. Eurasian Soil Science, 51(6):628–636. [ABSTRACT FROM AUTHOR]

Exposures to relatively high indoor radon (222Rn) levels represents a serious public health risk because Rn is associated with lung cancer (Darby et al., 2001; WHO, 2009; Oh et al., 2016; Sheen et al., 2016). The risk is high because radon, and its short-lived decay products in the atmosphere, contributes for about 60% of the total annual effective dose (UNSCEAR, 2000; WHO, 2009). Cancer risk is increased by smoking being almost 9 times higher than the risk to non-smokers exposed to similar levels (EPA, 2009). Due to these reasons, it is very important to assess the indoor exposure of public to radon and their daughters. Rn is a natural ubiquitous gas and its abundance is mainly controlled by the geology, and in particular by the soil and rock content of its parent nuclide (238U). Furthermore, bedrock characteristics (i.e. permeability and porosity) and also fault activity can affect the amount of Rn released in the ground (Ciotoli et al., 2007; Barnet et al., 2018). As such, in conditions of permeable and/or fractured bedrock and high uranium content, high indoor radon concentrations are expected (Bossew and Lettner, 2007; Gruber et al., 2013; Cinelli et al., 2015; Ielsch et al., 2017; Ciotoli et al., 2017). A non-natural contribution that controls the indoor Rn levels is home construction type and building materials (Vauptic et al., 2002; Appleton, 2007). Additionally, meteorological factors, such as wind, temperature and humidity, can affect the rate of Rn entry into the buildings (Porstendörfer et al., 1994; Miles et al., 2005; Schubert et al., 2018).In this work, we propose a new geospatial technique to construct the geogenic radon potential (GRP) map of the Caprarola municipality (northern Lazio, central Italy) characterized by recent (about 100 Kyr) volcanic deposits with high content in radon parent nuclides (Ciotoli et al., 2017). GRP map has been obtained by using Empirical Bayesian Kriging Regression (EBKR) technique with soil gas radon, as the response variable, and a number of proxy variables (i.e., content of the radiogenic parent nuclides, the emanation coefficient of the outcropping rocks, the diffusive 222Rn flux from the soil, the soil-gas CO2 concentration, the Digital Terrain Model (DTM), the permeability of the outcropping rocks and the gamma dose radiation of the shallow lithology. Furthermore, possible relationships between predicted soil radon values (i.e., GRP) and gamma radiation distribution with the indoor concentrations measured in private and public buildings has been investigated, respectively. The obtained results confirm that GRP maps provide the local administration of a useful tool for land use planning and that, the mapping of gamma emission, allows to a fast and effective evaluation of indoor radon hazard because it is mainly influenced by the building materials rather than other anthropic controls. [ABSTRACT FROM AUTHOR]

The numerical crop growth model IVINE (Italian Vineyard Integrated Numerical model for Estimating physiological values) was developed at our Dept. of Physics in Fortran language as a research model in order to evaluate the environmental forcing effects on vine growth, being vines generally strongly sensitive to meteorological conditions, and with the idea of using it for assessing climate change effects on grape growth. IVINE model simulates physiological and phenological vineyard processes with physically based parameterizations of most important processes taking place into vineyards, allowing to understand plant conditions at the microscale. It requires a set of meteorological data as boundary conditions. The main model outputs are: predawn leaf water potential, main phenological stages, leaf development, yield, and sugar concentration. The model requires to set some experimental parameters depending on the cultivar; at present, IVINE is optimized for Nebbiolo grapevine, a variety cultivated mostly in Piedmont region (northwestern Italy), but currently we are implementing it also for other varieties. As a first step, we tested the IVINE accuracy in actual climatic conditions, by performing simulations in the third millennium. In particular, we validated IVINE using experimental observations gathered in different Piedmontese vineyards in which some in-field measurements were performed. The results show performances similar or slightly better than those of other widely used crop models, thus increasing our confidence in the model reliability. We performed also a sensitivity analysis to highlight the effects of the variations of some input parameters on IVINE outputs. Among all, air temperature and soil moisture potential input variables were considered, as the most important ones. The results showed that most phenological phases decrease with increasing temperatures, while berry sugar content saturates at about 25.5 °Bx. Here, the main results of the sensitivity test and of the validation will be presented and discussed. [ABSTRACT FROM AUTHOR]

Reduction-oxidation (redox) reactions are central to the adsorption and release of carbon andnutrients in all soils. Different electron acceptors are used by microbes to gain energyaccording to their availability and ease of use. The presence and status of different electronacceptors and donors affects the availability of electrons in the soil. The redox conditions insoils can be described by the electric potential compared to a standard hydrogenelectrode. Recent developments in measurement methods have enabled continuous fieldmeasurements of redox potential. As redox reactions are key to carbon dioxide (CO2) andmethane (CH4) emissions and the release of phosphorus (P) and dissolved organiccarbon (DOC) from peat soils, the redox state of peatlands could be used to improvemodels that predict the functioning of these ecosystems under different water tableregimes. We present results from a redox measurement campaign of two years at the Lakkasuomire in southern Finland. The measurements were conducted at a mesotrophic site with threedifferent drainage regimes: pristine, short-term drainage and long-term drainage. At the site,also WTL, rainfall, air and soil temperature and other environmental variables aremeasured. Initial analysis shows that short- and long term drainage results in a more stable redoxregime in the surface layer (5 cm depth) and that long-term drainage results in a higher redoxpotential at 15 cm depth. In the pristime state, conditions are highly reducing most of the timealready at 15 cm depth. [ABSTRACT FROM AUTHOR]

The assessment of water resources in soil is of great importance in understanding the water cycle in the natural environment and the processes of water exchange between the soil and the atmosphere. It will also allow better use of water resources for agricultural, industrial and social purposes in anticipating and counteracting undesirable phenomena, such as floods, droughts or soil erosion. The main objective of the study was to assess water resources (years 2010-2013) in the surface soil layer for Poland from satellite and ground measurements using the SWEX (Soil Water Equivalent IndeX) index. Estimation of "water resources in soil" as seen from SMOS was conducted using the SWEX index proposed by W. Marczewski. SWEX is the result of multiplying soil moisture (SM) and radiation penetration depth (PD) for each pixel seen by SMOS satellite. SWEX is proportional to the water content in the soil "seen" by SMOS, but only in the PD. The PD being multiplication of the wavelength 0 equal to 21 cm was determined from the weekly SMOS L2 measurement data based on the relation between the real and imaginary dielectric constant. Soil moisture data from different depths from the agrometeorological stations were added up after weeks and multiplied for selected depths by soil moisture and then added up and statistically analysed. The relationship between the SWEX index calculated on the basis of SMOS satellite data and ground measurements data was analysed using Bland-Altman's statistics. Bland-Altman method was first proposed by J. Usowicz to compare soil moisture from SMOS and in-situ.Linear regressions between the SWEX and the total soil water resources received from the agrometeorological stations for each depth were not statistically significant. On the other hand, Bland-Altman's statistics indicated that the differences between SWEX and the sum of soil water resources from the stations, i.e. bias, were close to zero for layers from the surface up to 20-28 cm depending on the location of the station. These differences were greater in the case of soil moisture from thinner layers (positive) and also greater but negative from thicker layers from measurements in ground agrometeorological stations. Also for SMOS pixels in the vicinity of the central one, in which the measurement station was located, similar average difference results (close to zero) were obtained for the same layers (to 20-28 cm). Thus, Bland-Altman's analysis suggests that the use of the SWEX index for assessing soil water resources is the most reliable for the above layers in the years under study. Further research concerning the estimation of soil water resources from satellite data using the SWEX index taking into account the thinner and thicker layers and other parameters of the Bland-Altman statistics (e.g. limits of agreement, regression lines) is required.Acknowledgements. Research was partially conducted under the project "Water in soil - satellite monitoring and improving the retention using biochar" no. BIOSTRATEG3/345940/7/NCBR/2017 which was financed by Polish National Centre for Research and Development in the framework of "Environment, agriculture and forestry" - BIOSTRATEG strategic R&D programme. [ABSTRACT FROM AUTHOR]

The volcanic island of Tenerife (Canary Islands, Spain), comprises at least 4 distinct volcanic systems: the Teide complex, the Abeque dorsal (North West), the Pedro Gil dorsal (North East) and the Adeje dorsal (North South). The last eruption occurred in 1909, on the NW dorsal. Currently the volcano is in a quiescent state, showing only a moderate seismicity, weak fumaroles and diffuse soil gas emissions. However, in recent years, different geochemical and geophysical indicators are showing a departure from the previous background state of the volcano. In particular, since 2017, the occurrence rate of earthquakes located beneath the island, has shown a marked increase. This is only partially due to the technological improvement of the seismic networks operating on the island. In this work we demonstrate quantitatively that the observed increase is not an artifact due to the lower completeness magnitude of the catalogue. We computed the time varying a and b parameters of the Gutenberg-Richter distribution using a recently developed multiscale approach. This allowed us to obtain an unbiased estimate of the number of earthquakes having a magnitude higher than 0. We applied this approach on two independent seismic catalogues: the first coming from Red Sísmica Canaria (C7), managed by INVOLCAN; and the second from Instituto Geográfico Nacional (IGN). We show that the observed variations are consistent for both catalogues.The increase in the seismicity rate can be linked to the parallel rise in the diffuse emission rates of CO2 from the crater of Teide volcano. Both quantities started increasing after a significant swarm of long-period events (more than 700 detected) recorded in Tenerife on Oct. 2, 2016. This suggests that a massive injection of magmatic fluids into the island hydrothermal system is causing an increase of the pore pressure, triggering the microseismicity.At the this time the island is not showing significant ground deformation. This implies the absence of ongoing magmatic intrusion processes at shallow depth. However, the observed variations highlight an internal dynamic of the magmatic/hydrothermal system of Tenerife, indicating the need for a continuous improvement of the volcanic surveillance of the island. [ABSTRACT FROM AUTHOR]

The great Wenchuan Ms8.0 earthquake, on May 12, 2008, was one of the worst continentalearthquake events to have struck China in recent decades, and it killed more than tenthousand people in several cities along the western Sichuan basin. It is a new type ofearthquake that deserves further study. The variation in soil gas concentration serves as auseful tool for monitoring earthquakes. Some people have speculated that thermalabnormalities before earthquakes are related to the release of CH4. They always pay attentionto the total column of CH4. However, the same column concentration might correspond tothis distinct vertical structure. The focus of this study is to examine the spatiotemporal variation of CH4 in themid-upper troposphere during the Wenchuan earthquake (12 May, 2008) using AIRSretrieval data and to discuss the mechanism of the methane anomaly. Three indiceswere proposed and used for analysis: the Absolute Local Index of Change of theEnvironment (ALICE), the Vertical Concentration Gradient (Gradient), and the SuccessiveDifferential Value (Diff). Our results show that the methane concentration increasedsignificantly in 2008, with an average increase of 5.12*10−8, compared to the averageincrease of 1.18*10−8 in the previous five years. The Alice and Diff indices can beused to identify methane concentration anomalies. The two indices showed thatthe methane concentration distribution before and after the earthquake broke thedistribution features of the background field. As the earthquake approached, areasof high methane concentration gradually converged towards the west side of theepicenter from both ends of the Longmenshan fault zone. Moreover, a large anomalousarea was centered at the epicenter eight days before the earthquake occurred, anda trend of strengthening, weakening and strengthening appeared over time. TheGradient index showed that the vertical direction obviously increased before the mainearthquake, and the value was positive. The gradient value is negative during coseismic orpostseismic events. The gradient index reflects the gas emission characteristics tosome extent. We also determined that the methane release was connected with thedeep crust-mantle stress state, as well as microfracture generation and expansion. [ABSTRACT FROM AUTHOR]

To keep global warming below 1.5˚ C, agriculture will have to contribute as the other sectorsto achieve net negative emissions by the end of century [1]. Enteric fermentation andagricultural soils account for about 70% of agricultural non-CO2 emissions, and soil is themain source of nitrous oxide [1]. The challenge is to identify agricultural practices for GHGemissions mitigation and crop yield conservation, especially in the Mediterranean where fewstudies were conducted. In this study we measured soil fluxes of nitrous oxide (N2O), carbon dioxide (CO2) andmethane (CH4) in a field trial in Tuscany region (Italy), for two cropping seasons (2014 and2015) of tomato (Solanum lycopersicum L.) Perfect Peel, managed in fertigation. The maintreatment was irrigation with two levels: Ir1 (50% ET) and Ir2 (100% ET). The secondarytreatment was N fertilization with three levels: N0 (0 kg N ha−1), N1 (120 kg Nha−1) and N2 (170 kg N ha−1). Soil GHG fluxes were measured using a mobileinstrument developed within the project LIFE+ "Improved flux Prototypes for N2Oemission reduction from Agriculture" (IPNOA) (www.ipnoa.eu), equipped withhigh performance gas analysers and through-flow non-steady state chambers [2].Ancillary measurements were meteorological data, soil temperature and moisture, soilmineral nitrogen. Cumulative N2O emissions during the crop growing season rangedbetween 140 g N2O-N ha−1 and 1230 g N2O-N ha−1. They were significantlylower: in 2014 than in 2015 (-51%), in Ir1 than in Ir2 (-34%) and in N0 than inthe fertilized plots (-44%) and they were ordered as N0&#x003C;N1&#x003C;N2 in 2014 and asN0=N2&#x003C;N1 in 2015. Cumulative CO2 emissions ranged between 2771 kg CO2-C ha−1and 4130 kg CO2-C ha−1 and in 2014 they were significantly lower in N1 than inthe other two N levels (-18%), while in 2015 they were significantly lower in N0than in N1 (-7%), and N2 recorded an average value. Cumulative CO2 emissionswere significantly lower in Ir2 than Ir1 (-25%) in N0 in 2014, while in 2015 weobserved the opposite (+37%). In N1 and N2, CO2 emissions were not differentbetween Ir1 and Ir2 in both years. The CH4 uptake of soil ranged between -231g CH4-C ha−1 and -38 g CH4-C ha−1 and it was not affected by the treatments.Fresh fruit biomass was significantly higher in 2014 (143 ±7 t ha−1) than in 2015(75 ±4 t ha−1) and it was significantly higher in the fertilized plots (+48%) thanin N0. The main result of this study highlighted the chance to mitigate soil N2Oemissions reducing the irrigation level in fertigation, while preserving the tomatoyield. Differently, the reduction of N fertilizer rate, mitigated soil N2O emissionsonly in the first year and decreased the tomato yield as average of the two croppingseasons. [1] Intergovernmental Panel on Climate Change, IPCC (2014) Climate Change 2014Synthesis Report of the Fifth Assessment Report. [2] Livingston GP and Hutchinson GL (1995) Enclosure-based measurement of trace gasexchange: applications and sources of error. In: Matson PA, Harriss RC (Eds.), BiogenicTrace Gases: Measuring Emissions from Soil and Water. Blackwell Science, Cambridge.14–50. [ABSTRACT FROM AUTHOR]

Tropical forests are considered a natural sink for methane (CH4) and a natural source ofnitrous oxide (N2O), both important greenhouse gases (GHGs). To date, forest ecosystemexchange of CH4 and N2O has been mostly estimated based on GHGs exchange atthe soil–atmosphere interface only. However, trees of various climatic zones areknown to emit CH4 and N2O into the atmosphere. Recent research revealed tropicalwetland trees as considerable sources of CH4. Nevertheless, there is little known aboutCH4 and N2O exchange capacity of tropical trees growing under „non-flooded"conditions. We determined CH4 and N2O exchange of soil and stems of mostly endemic tree species(Syzygium borbonicum, Doratoxylon apetalum, Antirhea borbonica, Homaliumpaniculatum, Mimusops balata, Labourdonnaisia calophylloides) in a tropical lowland rainforest on lava flow of La Reunion Island in the South Western Indian Ocean. Weinvestigated (1) whether the tree stems exchange CH4 and N2O with the atmosphere, (2)how the tree fluxes contribute to the forest GHGs exchange, and (3) whether thetropical rain forest is a source or sink for CH4 and N2O at the beginning of the rainseason. The experiment was performed in Mare-Longue Nature Reserve (21˚ 21&#x2019;S, 55˚ 45&#x2019;E) inOctober-November 2018. The studied forest is situated on 400 years old pahoehoe basalticlava flow covered with irregular and thin soil layer. Fluxes of CH4 and N2O in mature treestems (n=24) and soil (n=24) were measured using non-steady-state chamber systems and aportable FTIR gas analyser. The stems of studied tree species were net sinks for both CH4 (-15.1 ± 2.2 μg CH4 m−2stem area h−1, mean ± s.e.) and N2O (-3.1 ± 0.8 μg N2O m−2 h−1). Such uptake potentialfor CH4 and N2O by tropical tree species represents a novel and unique finding which is incontrast to current limited studies presenting tropical trees as CH4 emitters. The soil was asignificant net CH4 sink (-79.5 ± 11.5 μg CH4 m−2 soil area h−1). However, the soil mightindicate also potential for CH4 emission under high soil water content (e.g. due to extremeprecipitation events), as one small-scaled wet soil area was characterized by CH4 emissions(192 ± 117 μg CH4 m−2 h−1). The soil N2O fluxes showed a high spatial heterogeneityincluding both N2O emissions and uptake (net flux -0.18 ± 1.61 μg N2O m−2h−1). Concluded, the studied tropical tree species were net sinks for CH4 and N2O. The tropicallowland rain forest situated on a lava flow seems to be a net sink for CH4 and toplay only a minor role in the global N2O exchange at the beginning of the rainseason. Acknowledgement This research was supported by the Czech Science Foundation (17-18112Y) and EUHorizon 2020 research and innovation programme (654182). Logistical support wasprovided by the Mare-Longue research station, funded by the POE, Reunion National Parkand OSU-Reunion. We thank Dr. Claudine Ah-Peng for scientific and organization help, andYoan Benoit, Pierre Stamenoff and Leszek Dariusz Laptaszynski for technical andorganization support. [ABSTRACT FROM AUTHOR]

This study reports the results of the comparison of the wavelet analysis and the conventional time series analysis (TSA) for the temporal pattern of high sampling frequency (15 min) soil radon. Both methods delivered good modeling results. The main achievement of the wavelet method is the identification and numerical characterization of the small but obvious semi-diurnal (12 h) periodicity. This semi-diurnal periodicity is the only temporal feature which is the same in the summer and winter seasons. In contrast, other time series components (cycle, diurnal periodicity etc.) vary over the considered seasons. This shows that the semi-diurnal periodic process is independent from atmospheric conditions and it is purely guided by the tidal gravitational forces causing soil gas partial pressure changes through the periodic contraction of the soil pore space. [ABSTRACT FROM AUTHOR]

Globally, nitrate is among the most common groundwater pollutants. Although,denitrification—the process eliminating nitrate to nitrogen gas—has been studied intensivelyfor a long time, we still lack a comprehensive understanding of its spatio-temporal dynamics.Despite recent advances in analytical tools, measuring denitrification in groundwater is stilllabour intensive, thus, time series data to study denitrification dynamics are scarce. Wepresent a new method to quantify denitrification dynamics in groundwater in acomparatively fast and cheap way. To this end, we continuously analysed in thefield dissolved N2—the product of complete denitrification—together with otherdissolved (noble) gases (4He, 40Ar, 84Kr, CO2) using a newly developed portable massspectrometry system in three riparian groundwater observation wells from Januaryuntil June 2018. Riparian zones are well known hot spots for nitrogen cycling,thus, we expect to detect a signal of N2 stemming from denitrification as well aselevated pCO2. Our aim is to quantify spatio-temporal dynamics of N2 production bydisentangling the N2 we measure into its three major sources: (1) atmospheric N2(due to air-water gas exchange), (2) excess air (the dissolution of entrapped airbubbles) and (3) denitrification. The theoretical amount of atmospheric N2 (1) canbe estimated based on the water temperature at recharge. The inert noble gasesserve as conservative proxies for gas exchange in groundwater which allow us tomodel the amount of excess air (2). Consequently, the remainder can be attributedto N2 stemming from denitrification (3). Our results show a strong signal of N2stemming from denitrification which exceeds the natural background concentration(i.e., atmospheric N2 due to air-water gas exchange and excess air) of up to 20%.Moreover, at one observation well we see a correlation (R2=0.75) between N2 and pCO2concentrations—a phenomenon not observed at the other two observation wells. We can linkand explain these discrepancies in denitrification and pCO2 patterns to differenthydraulic conductivities at the study site. Our work shows that continuous (noble) gasmeasurements in the field allow to study the dynamics of spatio-temporal denitrificationpatterns in riparian groundwater. Moreover, the method can be used for extensivesampling of larger areas (e.g., catchments) with a high spatial resolution, and thus,further advance our understanding of denitrification dynamics on larger scales. [ABSTRACT FROM AUTHOR]