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Nitrogen oxides (NO$_{\text{x}}$) are, due to their influence on air quality, tropospheric ozone production and human health, important trace gases in the atmosphere. They enter the atmosphere mostly by anthropogenic activities, with the largest part coming from fossil fuel combustion. The majority of NO$_{\text{x}}$ emissions are in form of NO which is converted to NO$_{2}$ within a few minutes and has a tropospheric lifetime of a few hours. Consequently, NO$_{2}$ is found near the emission sources and can be used for the detection of pollution. Due to the spectral characteristics of NO$_{2}$ it can be observed by the differential optical absorption spectroscopy (DOAS). The required measurements can be made by ground-based or satellite based remote sensing instruments, as in this study with Sentinel-5P.\\Sentinel-5P with the instrument TROPOMI was started in October 2017 and provides, thanks to the high spatial resolution of 3.5\,km x 7\,km, the possibility of detailed investigations on lifetimes and emissions of nitrogen oxides. Due to the higher resolution of Sentinel-5P compared to previous satellite instruments, there is a better identification of different emission sources also on small scales such as individual cities.\\In this study, the first year of Sentinel-5P data is analyzed for different wind situations based on ECMWF wind data. The Sentinel-5P data is averaged for eight different wind directions to get clear emission patterns. Out of that lifetimes and emissions are calculated. This evaluation method in combination with the high spatial resolution makes it possible to determine different emission sources within a city. Emission sources can be separated and single plumes can be analyzed. [ABSTRACT FROM AUTHOR]

The Amazon Basin represents the largest intact tropical rainforest ecosystem. On a large scale the Basin is characterized by an east-west gradient in geology and soil fertility, with rather nutrient (particularly P) poor soils in the Eastern Amazon and more fertile soils in the West. On a smaller scale, local topography influences soil mineralogy, texture, and nutrient stocks and availability. Such gradients have been shown to affect plant productivity, but how the decomposition of organic matter by soil microbial communities, which is crucial for making nutrients available for plants, is controlled by such gradients has rarely been evaluated. We therefore collected forest soils from representative regions in the Eastern, Central and Western Amazon Basin at different topographic locations and two different soil depths (0-5 cm and 5-15 cm) to cover a wide range of soil types, texture and nutrient availability. In these soils we determined nutrient pools, microbial biomass and growth, as well as microbially mediated nutrient cycling rates to determine how these pools and processes affect microbial carbon use efficiency (CUE), an important indicator for microbial C sequestration. Our preliminary results confirmed a pronounced gradient of total soil P from east to west that was also related to soil texture, with highest total P and available P (both Olsen and Bray-P) concentrations in younger, silty soils in the Western Amazon. Microbial biomass was positively related to both total and available P concentrations, and even more strongly positively correlated to soil organic N pools. Extracellular enzyme activity rates increased with microbial biomass and were highest in nutrient-rich soils. We hypothesize that soils with higher nutrient availability will not only foster high soil microbial activities, but similarly increase microbial CUE, thus emphasizing the importance of soil microbes for C sequestration. [ABSTRACT FROM AUTHOR]

In many arid parts of the world, dust from deserts and other dry surfaces can be upliftedinto the air and become the largest fraction of atmospheric aerosols. Dust aerosoloutbreaks can affect large areas, and have important effects on air quality, visibility,human health, and also on the transport of trace elements towards remote oceanregions. Desert dust outbreaks can be observed from space in visible satellite imagesand quantified by aerosol retrieval methods which separate the contributions fromsurface reflection, scattering on air molecules and scattering by particles on theobserved top of atmosphere reflectance based on the analysis of discrete wavelengthbands. A few years ago, a spectral interference of the surface spectral reflectance of deserts wasfound in GOME-2 satellite retrievals of atmospheric nitrogen dioxide (NO2) from spaceborne observations in the wavelength region 450 - 497 nm. This spectral signature whichappears to be unique to certain desert soils was subsequently also identified in measurementsof other satellites and in airborne data. Here, we use measurements of the TROPOMI instrument on the recently launched S5Psatellite to investigate the global distribution of the spectral sand signal and show that it is notonly found over deserts, but can also be used to detect large desert dust aerosol events, mainlyover the ocean but also over land. [ABSTRACT FROM AUTHOR]

Long-term intensive cultivation in paddy soils strongly impacts soil pedogenesis and leads to accumulation of organic matter and the stratification of nutrients and oxygen in the soil profile. However, knowledge about the dynamics of soil microbial communities during continuous rice cultivation at long time scales including progressive and retrogressive stages is limited. In particular, the driving forces of community assembly also still remain poorly resolved. Therefore, we characterised the temporal and spatial changes in soil bacterial, fungal communities and functions using high-throughput sequencing and quantitative-PCR-based chip (targeting 64 microbial functional genes for C, N, P, S and methane metabolism) along a 2000‐year chronosequence of soils under paddy and adjacent non-paddy management in the Yangtze delta of China, a coastal region where paddy soils originated. Soil depth profiles were sampled from the paddy fields (6, 50, 100, 300, 700, 1000, and 2000 years of paddy use), the adjacent arable chronosequence (50, 100, 300 and 700 years of dryland use) and a tidal wetland (estuarine sediment, representing the parent material for paddy and arable soil reclamation). Results showed that across multiple time-scales ranging from decades to millennia, significant shifts in soil bacterial and fungal communities with soil depths occur, indicating paddy soil development and a microbial succession since reclamation from tidal wetlands. The initial stages of paddy and dryland soil development exhibited a higher phylogenetic ß-diversity than the soils at later successional states. Patterns of α‐diversity for microbial groups differed along soil chronosequence and with depth. Microbial α‐diversities in topsoil was greatest in soils of intermediate age, while the α‐diversities in subsoil was greatest in 1000-year cultivation. Moreover, allogenic succession of microbial communities was mostly driven by shifts in the soil physicochemical properties, especially pH and nutrient availability including organic matter and phosphorus during paddy soil development. Further network analysis showed that soil microbial communities were more interconnected at late successional stages than at initial stages, coinciding with a higher dymanics in turnover and environmental variability. Our study implies that, long-term rice cultivation substantially alters topsoil and subsoil microbial functional structure, leading to functional homogenization. Additionally, soil functions related to the acceleration of nutrient cycling, necessary for high crop yields, are promoted by long-term rice cultivation. [ABSTRACT FROM AUTHOR]

Glyoxal (CHOCHO) is an intermediate product in the atmospheric oxidation of most volatile organic compounds (VOC) and an indicator of secondary organic aerosol (SOA) formation in the atmosphere. It is mainly emitted by natural sources but there also is a significant contribution from human activities and fires. Glyoxal is characterized by a short life time (few hours) in presence of sunlight, because it is removed from the atmosphere by photolysis, SOA formation, oxidation by OH, as well as by physical processes such as wet and dry deposition. CHOCHO can be retrieved from space-borne observations using the Differential Optical Absorption Spectroscopy (DOAS) method. Here, measurements from the TROPOMI instrument, which was launched on the Sentinel-5 Precursor (S5P) platform in October 2017, are used for the observation of glyoxal. Previous studies show unexpectedly high amounts of glyoxal over ocean regions, where no sources of glyoxal are expected. Also, as consequence of its short lifetime, long range transport of glyoxal is unlikely. However, in this study some evidence of transport of glyoxal produced from fire emissions was identified over the Canadian region, indicating possible recycling processes in the plume.During summer 2018, large wildfires occurred in Canada's British Columbia region. These fires create elevated atmospheric levels of many different gases in the atmosphere, e.g. CO, NOx, O3, SO2, CO2, HCHO, CHOCHO and aerosols affecting air quality. For many of the fires, glyoxal hot spots can be identified in the measurements. Surprisingly, elevated levels of glyoxal remain visible for several days and over long distances from the sources until they disperse. The glyoxal S5P observations, in combination with forward trajectories simulated with the FLEXPART model, are used to investigate the glyoxal long range transport during the study period. FLEXPART simulations describe the evolution of the plume of glyoxal for most of the fire events, and provide estimates of the effective life time of glyoxal in the plumes. [ABSTRACT FROM AUTHOR]