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The hydrological effects of straw mulching and salvage logging have been widely experimented in the Mediterranean forests affected by wildfires. In contrast, knowledge about the impacts of these post-fire management techniques on the physico-chemical properties of burned soils is poor, especially many years after the fire. In particular, no studies have evaluated the soil changes after the combinations of soil mulching and salvage logging after wildfires in Mediterranean forests. To fill this gap, this study explores the effects of straw mulching and salvage logging, applied individually or in combination to a burnt forest of Pinus halepensis Mill. of central-eastern Spain, on the physico-chemical properties of soil six years after a wildfire. Both the post-fire techniques significantly altered the organic matter, phosphorous, and carbonate contents of the burned soils as well as their C/N (carbon/nitrogen) ratio, while the texture and other chemical properties (pH, electrical conductivity, total nitrogen, potassium, cations/anions, and active limestone) of the soils were not significantly affected by these post-fire treatments. Organic matter (OM) and phosphorous (P) contents increased by 57% and 69%, respectively, in mulched soils in comparison to the burned but untreated plots. In logged soils, the OM increased by 27%, while P decreased by 17%. Salvage logging after straw mulching increased OM, albeit less than under the individual soil treatments (+13%), but noticeably reduced P (−39%). The C/N ratio practically underwent the same variation (+15–20%) after the combination of the two treatments. The principal component analysis and the agglomerative hierarchical cluster analysis applied to the soil properties measured in the plots under the individual and combined management show that the effects of salvage logging on soil properties appear to be more impactful compared to straw mulching. [ABSTRACT FROM AUTHOR]

Although several management options are adopted to redirect post-fire forest ecosystems towards less vulnerable and more resilient and functional communities, little is known about the interactions among tree stand age, pre-fire forest management, and slope aspects, and their consequences for plant species and soil properties recovery immediately after severe wildfires. To address this knowledge need, this study evaluates the post-fire changes in species richness and diversity (with a specific focus on regeneration mechanisms and life forms) of regenerating plants as well as the main physico-chemical and biological properties of burned soils with the reciprocal relations. Plant cover and diversity, and many soil properties have been monitored in forests of southeast Spain with mature, middle and young stands, presence of pre-fire treatments or not, and north and south hillslopes about one year after the fire. To this aim, the reciprocal relationships among soil properties and plants were evaluated adopting a combination of statistical techniques (PERMANOVA, Non-metric Multi-Dimensional Scaling, Distance-based Linear Modelling, Distance-based Redundancy Analysis, and Spearman correlation analysis). The damage to soil and vegetation was so high that both plants and pre-fire soil properties slowly recovered. Only a few life forms of vegetation (geophytes and herbaceous chamaephytes) were influenced by the stand age. If combined with soil aspect, stand age resulted in significantly lower germinating species in mature stands and lower resprouters in young stands, both on south hillslopes. Plant diversity was high, and the post-fire regeneration did not change the species richness and evenness. The post-fire changes in soil properties were limited, and only slight small differences in pH and betaglucosidase among stands of different age were found. No evident associations between soil properties and plant diversity were revealed by the low correlation coefficient. The low variance in plant cover and diversity, as well as in soil properties, resulted in a low accuracy of the dbRDA model to reproduce its variability among sites with different pre-fire characteristics. • An extremely high fire severely damaged soil and vegetation, which both slowly recovered. • Stand age resulted in lower germinating species in mature and south-aspect stands. • Stand age yielded lower resprouters in young stands on south hillslopes. • Post-fire regeneration did not change species richness and evenness. • Post-fire changes in soil properties were limited (except for pH and betaglucosidase). [ABSTRACT FROM AUTHOR]

Observed variations in the ground electrical conductivity (σb*) measurements obtained with EMI instruments depend on several soil proxies that influence crop growth and development such as salinity (σe), contents of water (θw), clay (wc) and organic matter (wom) and bulk density (ρb). However, the relative contributions of all these to σb* are unknown. This knowledge is needed to improve the planning and interpretation of σb* data for precision agriculture applications. Recently, a semi-empirical model has been developed to relate σb* measurements taken with an EM38 device to σe, θw, wc, wom and ρb and also soil temperature (t). In this work this model was subjected to a global sensitivity analysis (GSA) based on the soil data obtained during two surveys carried out, one in summer and the other in autumn, in an ample irrigated area in SE Spain. On the basis of the multiple linear regression meta-models developed for the σb* measurements, these were found to linearly respond to the soil properties (R2 between 0.92 and 0.96) and thus, the GSA could be based on their standardised regression coefficients. According to these, the soil characteristics explain the following percentages of variance in σb* (PV): 30–34 (σe), 8–20 (θw), 32–47 (wc), 0.6–2.6 (wom), 5.7–7.5 (ρb) and 0.3–0.4 (t) with changes from the summer to the autumn season of − 4, − 12 and + 15 in the PV explained by the most influential properties, respectively, σe, θw and wc. The results of the GSA will help the planning and interpretation of σb* measurements for improving crop management. [ABSTRACT FROM AUTHOR]

Granite massifs often contain caves, with dimensions ranging from a few meters up to 1,000 m, also referred to as pseudokarst. The speleothems in such caves are mostly composed of either Si-rich (commonly opal-A) or Al-rich authigenic mineraloids. Whereas the formation and geochemical composition of opal-A biospeleothems have been studied and are fairly well understood, knowledge on the Al-rich analogues is scarce. This work reports for the first time a study on the composition, accretion process, age and growth rate of an Al-rich speleothem type flowstone from the A Trapa Cave System (Galicia, NW Spain), developed in a granite cave. To understand the growth process, trickling water was analyzed and the deposition environment inside the cave was characterized. We found that the speleothems are alternating Si- and Al-rich layered deposits formed between 1,635 ± 75 and 1,243 ± 58 cal BP by percolating water that carries underground mineral grains, dissolved ions, and organic matter from soil and the weathered bedrock above the cave. [ABSTRACT FROM AUTHOR]

Textural, geochemical and geochronological analyses on two gravity and two box cores recovered from the outer and inner sectors of the Ría de Muros allowed reconstructing and timing the anthropogenic imprint on the sedimentary record from this ría. The chronological framework for the last 8 kyr was built based on Pb-210 dating (Constant Rate of Supply model) and C-14 dating. Recent sedimentation rates were an order of magnitude higher than those of the oldest analyzed sediments, and the periods of upwelling enhancement were constrained. Assessing the human influence on sediment metal contents required the establishment of local background levels. Since the 16th century the enrichment factors of copper, zinc and lead increased (up to 2.7, 1.5 and 2.1, respectively, at or close to present), and a remarkable increase in the fine-grained particles' content happened in the outer ría sector, due to deforestation. The anthropogenic signature identified in the sedimentary record is assigned to fishing, harbor activities, mining, salting, and, or canning activities, depending on the considered period, which caused a local demographic increase since the 16th century in the region. Such population growth caused a rise in the marine signature of the organic matter, which likely results from enhanced primary production due to eutrophication caused by increased soil erosion and human and livestock waste inputs. Furthermore, the metal enrichment trend during the 20th century, which was more significant in the inner than in the outer ría sector, follows the different demographic evolution of the villages (related to urban and industrial development). The present study highlights the need for conjunction of varying dating techniques when reconstructing the anthropization trends in coastal environments. [ABSTRACT FROM AUTHOR]

This study analyses the smouldering combustion on soils that took place during the wildfires that occurred in Rocallaura (Northeastern Spain). The smouldering combustion after the first event, 23 June, was the potential source of flaming fire re-ignition of the second event, 19 July 2016. Re-ignitions are an important challenge for the firefighting system. Budget and efforts are spent on controlling these re-ignitions that can ultimately cause the collapse of the response system if the re-ignitions happen during periods of simultaneous fire events. Our objective is to contribute to better understand the dynamics of the smouldering combustion of organic soils associated with these wildfires and the impact on the Pinus halepensis Mill. forest ecosystem. Transects were established in adjacent control and post-fire zones. Laboratory analyses were conducted to determine some physical and chemical properties of both the duff and mineral soil. Using these variables, we estimate thresholds of duff ignition probability, percentage of duff consumption and smouldering combustion spread rates. Overall, we provide a set of tools for evaluating re-ignitions in forest ecosystems. We conclude that the concept of fire persistence should be a new variable for consideration in present and future analysis of fire regimes and demonstrates the significance of introducing smouldering combustion and re-ignition within the strategic framework of the wildfire hazard and integrating these phenomena into forest planning and management. [ABSTRACT FROM AUTHOR]

To understand the density patterns of the tube-forming polychaete Diopatra neapolitana and their relationship with environmental factors, an extensive sampling was conducted in an intertidal, commercially exploited population in the Ría de Vigo (NW Spain). Interpolation of the sampled densities was carried out by Inverse Distance Weighting (IDW). The results showed a heterogeneous, patchy distribution: the average density was 2.56 tubes/0.25 m2, although some areas exhibited a density with more than 30 tubes/0.25 m2 while in others the species was completely absent. Our data also showed that the presence of vegetation (either algae or Zostera) increased the densities of D. neapolitana. To better understand this finding, a second sampling was conducted targeting the three main permanent habitats identified in the study area. This revealed that the spatial location within the intertidal was the most important factor affecting densities. The higher densities observed with increasing latitude and longitude are a consequence of the higher flooding time, that means less water stress and longer submergence time, and involves a reduced likelihood of being caught by shellfish harvesters. The second most important factor explaining D. neapolitana densities was the sediment organic matter content, which is consistent with the observation that the presence of vegetation increases the density of tubes. This work is the first comprehensive approach to understand the spatial structure of densities of D. neapolitana. [Display omitted] • A study of the spatial densities of D. neapolitana was conducted using IDW analysis. • This species is heterogeneously distributed, forming aggregations or patches. • Vegetal cover (algae or Zostera) favours the occurrence of its higher densities. • Both flooding time and sediment organic matter content determine its distribution. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Photo-Fenton with Fe3+-EDDS removes CECs regardless water composition. • 80% CEC removal after 15 min in 5 real WWTP effluents. • Nature and not the load of organic matter has impact on CEC removal. • Short reaction time to remove CECs encourages continuous flow operation. • Mechanism developed with synthetic effluent explains reactions in real wastewater. Abstract This paper presents for the first time the treatment of contaminants of emerging concern (CECs) in a systematic study in different municipal wastewater treatment plants (MWWTPs) of the Mediterranean area, more than 1000 km away. Solar photo-Fenton process at neutral pH with Fe3+-EDDS has been demonstrated to be very efficient under controlled conditions and must be validated in realistic and variable conditions such as real MWWTP effluents of different composition. To this end, CEC removal was studied in effluents from 5 treatment plants in the Mediterranean area of Spain, the inorganic and organic composition varying in the range 161–641 mg L−1 (sulfate), 133–538 mg L−1 (chloride) and 10–20 mg L−1 (dissolved organic carbon). More than 45 CECs were quantified in MWW and results showed that the effect on CEC elimination of the concentration of anions and organic matter was interfered by the nature of the organic matter. However, origin and composition of MWW was not critic for attaining >80% degradation of CECs after 15 min of reaction. Moreover, conventional anions (sulfate, chloride) had a positive effect on CEC degradation rate. This paper demonstrates the consistency and predictability of the solar photo-Fenton process at circumneutral pH for treating CECs in simple and cheap photoreactors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Aeolian deposits modify pedogenesis processes and their evolutionary trend. • Fossilization soils by aeolian sediments promotes of carbonation and decalcification. • Intense evolution of hyper-quartz sediments leads to final processes of podsolization. Aeolian deposition in coastal system can modify pedogenic processes or provide parent material for new pedogenesis cycles. In Galicia region (NW Spain), as in other regions of the world, the pedogenic processes associated with aeolian deposits under coastal conditions are little know. These processes are also conditioned by the development time from the formation of the sedimentary deposits, which in the case of the Galician coast is highly variable. The main objective was to identify the effect of aeolian deposits on coastal soils, through the characterization and classification of several soil profiles, and the identification of the main pedogenic process that contributed to their formation or modification. The studied soils presented one and two pedogenic cycles as well as in each one different level of pedogenic evolution. The soils with one pedogenic cycle were Endoleptic Umbrisol (Loamic, Hyperdystric, Hyperhumic, Pachic) from Xuxurantes and Haplic Umbrisol (Arenic, Humic, Pachic) from Cabo Vilano. The soils with two cycles were found in Muxia (Aeolic Calcaric Arenosol (Ochric-Novic) over Haplic Phaeozems (Endoloamic)) and Cementerio de los Ingleses (Albic Umbric Podzol (Pantoarenic)). This last type of soil constituted one more step in the evolution of aeolian deposits (first cycle of pedogenesis in the Muxia profile). Thus, changes in the pedogenesis processes and mechanisms were conditioned by the presence of a superficial aeolian deposition as well as the proximity to the coast and determine a chronosequence of the processes in the aeolian sediments. [ABSTRACT FROM AUTHOR]

Purpose: Shallow soils previously cultivated under terraced systems may change their properties after agricultural release and spontaneous plant colonization. Investigations were conducted in terraced fields (NE Spain) to prove that vegetation installed after the abandonment may generally improve soil properties by the formation of stable organic horizons. However, restriction in plant species along the natural vegetation succession and intensification of erosion processes may occur after abandonment depending on fire frequency and soil use history. Materials and methods: Ten environments with different plant covers under a Lithic Xerorthent were selected and erosion plots (Gerlach type) installed providing their best adaptability at the terrace scale. Selected soil environments represented the sequence of abandonment: from current poorly cultivated soils, soils under pasture, soils under shrubs, and soils under stands of pine and cork trees. Relevant rainfall events producing runoff and erosion were recorded from November 2011 to May 2012. Erosion rates and erosion components were analysed in sediments and water in order to monitor carbon, nitrogen and other nutrient removal by overland flow. Similarly, the physical and chemical properties of the soil environments under study were determined at the same time interval of runoff erosion. Results and discussion: Soils under pasture, vines and recently burnt pine forest produced the highest runoff followed by soils under shrubs and forest. However, eroded soil yields and nutrient removal were much higher in cultivated soils and soils in recently burnt sites, which had shown poorer soil properties with respect to soils abandoned for longer and preserved by fire. Fire-affected soil environments also showed a thinner organic horizon and reduced water retention. Although erosion rates and nutrient depletion were low in all environments with respect to other areas of Spain, higher splash than water erosion was an early warning indicator of the high susceptibility to degradation of these shallow soils. Conclusions: Results outlined that the renaturalization dynamics after agricultural abandonment are complex biophysical processes involving the parent material, depth to bedrock and other soil properties as well as the succession of vegetative cover and plant associations responsible for building a new soil mantle contrasting with erosion processes. Planning for management of land abandonment is strongly recommended. [ABSTRACT FROM AUTHOR]

Wildfire is a recurrent phenomenon in Mediterranean ecosystems and contributes to soil degradation and desertification, which are partially caused by alterations to soil organic matter (SOM). The SOM composition from a Cambisol under a Mediterranean forest affected by a wildfire is studied in detail in order to assess soil health status and better understand of soil recovery after the fire event. The soil was sampled one month and twenty-five months after the wildfire. A nearby unburnt site was taken as control soil. Soil rehabilitation actions involving heavy machinery to remove burnt vegetation were conducted sixteen months after the wildfire. Immediately after fire the SOM increased in topsoil due to inputs from charred vegetation, whereas a decrease was observed in the underlying soil layer. Twenty-five months after fire soil-pH increased in fire-affected topsoil due to the presence of ashes, a decrease in SOM content was recorded for the burnt topsoil and similar trend was observed for the water holding capacity. The pyro-chromatograms of burned soils revealed the formation of additional aromatic compounds. The thermal cracking of long-chain n -alkanes was also detected. Solid-state 13 C NMR spectroscopy supported the increase of aromatic compounds in the fire-affected topsoil due to the accumulation of charcoal, whereas the deeper soil sections were not affected by the fire. Two years later, soil parameters for the unburnt and burnt sites showed comparable values. The reduction of the relative intensity in the aromatic C region of the NMR spectra indicated a decrease in the charcoal content of the topsoil. Due to the negligible slope in the sampling site, the loss of charcoal was explained by the post-fire restoration activity, degradation, leaching of pyrogenic SOM into deeper soil horizons or wind erosion. Our results support that in the Mediterranean region, fire-induced alteration of the SOM is not lasting in the long-term. [ABSTRACT FROM AUTHOR]

Soil water repellency (SWR) has been reported under different soils, land uses and regions of the world, particularly in forest land and after wildfires, yet the understanding of this variable in agricultural lands is still rather limited. This study presents the characterization from field-based measurements of SWR in four contrasted olive groves ( Olea europaea L.) in Spain in terms of different environmental conditions and management: abandoned and commercial farms under permanent cover crop, conventional tillage and herbicide use. The main objectives were [1] to evaluate the potential occurrence, intensity and persistence of soil water repellency in different types of olive groves and [2] to explore its spatio-temporal features as well as the influence of soil properties such as organic matter (OM) and soil moisture. The Water Drop Penetration Time test (WDPT) was used in situ to assess SWR values. Measurements were carried out in two areas for each of the four groves: below and between the tree canopies. A high spatial and seasonal variability was observed. SWR was absent (WDPT = 0 s) for the olive groves under conventional tillage and with the lowest values of OM (OM-mean = 2.04%). The maximum WDPT values were found for cover crop under canopy in summer (WDPT-max = 610 s) and on the lanes in autumn (WDPT-max = 468 s). SWR was developed during the dry season, and to be reduced during the rainfall season as the organic compounds might be reoriented and turned amphiphilic. Strong water repellent values (> 60 s) were related with extremely high OM values (> 12%) for the cover crop orchard. [ABSTRACT FROM AUTHOR]

Analyses of the total organic carbon (TOC), total nitrogen (TN), C/N ratio and isotopic ( δC and δN) composition of organic matter (OM) in surficial sediments, integrated with hydrographic measurements, have been used to evaluate the sources and distribution of sedimentary organic matter on the Catalonian shelf and slope (northwest Mediterranean Sea). We examined the effects of the variations on meiofauna. Settled OM in February, April and October displayed δC relatively closer to marine algae (mean −22.4 ‰ ± 0.1) than that in July (−23.3, −23.7 and −22.7 ‰ at 60, 600 and 800 m, respectively). Lowest δC (−23.7 ‰) and high C/N (~10), indicative of mixed continental and marine organic contributions, were detected principally at the head of the Buscarró Canyon (at 600 m) in July, ca. 2-3 months after the maximum river discharge. We observed significant changes in total meiofaunal density among seasons in the canyon, with the highest values in July and October. On the adjacent slope at 800 m there was no significant increase of total meiofauna in those months. Although export of marine organic matter from surface layers was the main food source in the study area (on average 71.2 % estimating marine and terrestrial OC by binary models; 68-71 % at the most by SIAR models), advection of organic matter from the continental edge and/or resuspension of organic matter along submarine canyons may seasonally alter the composition of deposits on the slope, particularly in July with % OC of terrestrial origin reaching 48.7 % in Buscarró canyon, shifting the basal food-web of deep ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Current environmental research is paying increasing attention to reliable analytical surrogates of soil quality. In this work a series of molecular features of soil organic matter were studied in different soil types from Central Spain with the purpose of identifying the soil functions most closely correlated with specific pools of soil organic matter and their structural characteristics. Soil physical variables—including bulk density, total porosity, aggregate stability, available water capacity and water infiltration parameters (Kostiakov's equation coefficients)—were determined. The major soil organic fractions (lipids, particulate free organic matter, fulvic acids, humic acids and humin) were quantified using standard procedures and the soil organic matter was characterised by spectroscopic techniques. Statistical data treatments including simple regression, canonical correlation models and multidimensional scaling suggested two well-defined groups of physical properties in the studied soils: (i) those associated with organic matter of predominantly aromatic character (e.g., water infiltration descriptors), and (ii) soil physical variables related to organic matter with marked aliphatic character and comparatively low degree of humification (e.g., porosity, aggregate stability, available water capacity and field air capacity). From the practical viewpoint, the results support the idea that the detailed structural study of the soil organic matter is useful for accurately monitoring soil physical status. The only determination of total soil organic carbon ought to be complemented with qualitative analyses of the organic matter fractions, at least at the spectroscopic level, which to large extent help to explain the origin of the variability in soil physical properties and can be used for the early diagnosis of possible degradation processes. [Copyright &y& Elsevier]

• This work evaluates the effectiveness of postfire strategies on soil functionality. • Fire may shift the trajectory of microbiological soil properties. • Post-fire management altered microbiological soil properties and soil functionality. • Contour-felled log debris and log erosion barriers enhanced soil organic matter. Contour-felled log debris (CFD) and log erosion barriers (LEB) are two restoration practices used worldwide on hillslopes to avoid soil erosion after wildfires. Although significant work has evaluated the effectiveness of these practices on soil loss prevention, their effects on soil properties have been little researched to date. Here, the effects of CFD and LEB treatments on several physico-chemical and biological soil properties were investigated across four post-fire zones in Mediterranean forest (Sierra de Los Donceles, Spain). Results suggest that post-fire management similarly altered the recovery of microbiological soil properties and soil functionality for both CFD and LEB treatments. Post-fire management enhanced soil organic matter (SOM) and basal respiration, while suppressing soil microbial activities. SOM enhancement at our plots may have been associated with suppressed soil microbial decomposition activity due to post-fire increases in electrical conductivity. Plots with post-fire management recovered microbiological soil properties better than unmanaged burn plots, but not to the same level as nearby unburned plots. LEB and CFD may not only be effective in retaining sediments, but also in improving post-fire microbiological soil properties in comparison to unmanaged plots. However, after eight years of post-fire management, soil microbiological soil properties did not completely recover compared to unburnt areas. That is, fire may shift the development trajectory of microbiological soil properties so that they may no longer be able to return to the same unburnt conditions. Post-fire restoration plans should consider the use of LEB and CFD when aiming to aid soil-related ecosystem recovery processes after wildfires. [ABSTRACT FROM AUTHOR]

Abstract: Pig slurry (PS) is widely used as a fertilizer for the production of maize in Spain. Field testing was carried out over a ten-year period to compare the performance of maize fertilized with PS (45 m3 ha-1, equivalent to 315 kg nitrogen (N) ha-1 year−1) (PS45) and mineral fertilizer (300 kg N ha-1) (N300) along with a N-free control (N0). Grain yield, biomass at physiological maturity, plant N uptake and soil nitrates (NO3 −–N) were measured as agronomic properties. Soil physical, chemical and biological parameters (as acid-phosphatase activity, earthworm abundance, CO2 Flux, Shannon H′ diversity index (H’), number of utilized substrates (NUS), microbial biomass carbon (MBC), resistance to penetration (RP) and organic matter (OM) among others) were measured at harvest in the last two years of the experiment. The mineral fertilizer promoted the highest grain yield and N uptake by the plants, but also resulted in the highest residual NO3 −–N levels in the soil. Interestingly, most of the indicators revealed no statistically significant differences between the treatments in either test years, although a general trend was observed (N0 < N300 < PS45). The repeated application of PS had a beneficial impact on the soil quality over time but did not improve grain yields. [Copyright &y& Elsevier]

Small lakes and wetlands from high elevation within the Sierra Nevada Range (southern Spain) preserve a complete post-glacial Holocene record. Isotopic, TOC and C/N analyses, carried out on a sediment core, show various stages in the evolution of the Borreguiles de la Virgen, which today constitute a small bog at about 2,950 m above sea level. Glacial erosion generated a cirque depression, which became a small lake during the first phase of infilling (from 8,200 to 5,100 cal yr BP), as suggested by sedimentary evidence, including an atomic C/N ratio generally below 20, low TOC values and the highest δC and δN values of the record. These results imply significant algal productivity, which is confirmed by the microscopic algal remains. Drier conditions became established progressively in this area from 5,100 to 3,700 cal yr BP. Subsequently, the lake evolved into a bog as shown by geochemical evidence (C/N ratios above 20, high TOC content and low δC values). Unstable conditions prevailed from 3,600 to 700 cal yr BP; an extremely low sedimentation rate and scarcity of data from this period do not allow us to make a coherent interpretation. Fluctuating conditions were recorded during the last ~700 cal yr BP, with wetter conditions prevailing during the first part of the interval (with C/N rate below 20) up to 350 years ago. In general, a gradual trend toward more arid conditions occurred since ~6,900 cal yr BP, with a further increase in aridity since ~5,100 cal yr BP. This evidence is consistent with other contemporaneous peri-Mediterranean records. [ABSTRACT FROM AUTHOR]

Abstract: Suspended load dynamics were analyzed for the period 2007–2009 in a semi-meandering cross-section under different hydrological conditions. Samples were collected at four different points of the cross-section. During “low discharges” (≤600 m3/s) suspended load samples were collected at-a-monthly basis, whereas at “high discharges” (>600 m3/s) sampling was conducted intensively (at-a-daily basis during the first stages of the flood event). Results indicated that during low discharges, both organic and inorganic suspended load concentrations tended to be uniformly distributed across the fluvial section; but during high discharges, two distinct areas were found: an area extending from the “Inner-bank” to the “Channel centre” (Area-I) with higher suspended concentrations (organic and inorganic) than those recorded in the “Outer bank” (Area-II). This phenomenon was likely related to the formation of secondary flow velocity cells and the activation of new sources of sediment. In addition, a non-significant relationship between organic suspended load and water flow was observed in the outer-bank. At-a-monthly basis, the analysis of the suspended load showed the existence of an intra-annual cycle of the inorganic concentrations, with a progressive increase from October to March followed by a decrease from March to September. Nevertheless, the organic suspended load did not show any trend, being equally distributed along the year, suggesting that other sources of organic matter besides phytoplankton are predominant. [Copyright &y& Elsevier]

This study analyzes the performances of 2 methods of oxidation based on ozone, namely ozonation and ozone combined with hydrogen peroxide (O3/H2O2), on two biotreated municipal wastewater effluents. The main parameters monitored to evaluate the effectiveness of the processes were Chemical Oxygen Demand (COD), Dissolved Organic Carbon (DOC) and Biochemical Oxygen Demand (BOD5). Ozonation and O3/H2O2 treatment removed 44% and 48%, respectively, of the COD, after 90 min, of the secondary effluent of Calafell wastewater treatment plant (Spain). On the secondary effluent from the Grasse wastewater treatment plant (France), these same treatments (O3; O3/H2O2) achieved, respectively, a degradation of 52% and 100% of the COD after 60 min. The transferred ozone dose (TOD) during Calafell and Grasse effluents' ozonation were 122 mg·L-1 and 77 mg·L-1 after 90 min, respectively. A low removal of DOC was monitored during both O3 or O3/H2O2 treatments applied to Calafell wastewater, respectively 12% and 14%. Better DOC reductions were obtained on the water of Grasse treated with O3 or O3/H2O2, respectively, 48% and 60%. In addition, ammonia nitrogen was oxidized to nitrate nitrogen thus giving rise to an over ozone consumption. And finally, both processes proceeded with an increase of pH values. These results highlight the strong dependency of O3 or O3/H2O2 treatment effectiveness in terms of dissolved organic matter (DOM) removal and ozone consumption on wastewater composition (organic and inorganic substances). [ABSTRACT FROM AUTHOR]

Abstract: The study of macroscopic charcoal particles from peat bogs has led to a better understanding of climate, vegetation and fire history, and human impacts. To determine the relationship between human activities and the role of fire events in vegetation change during the last 3300cal yr BP, we present the results of a multi-proxy approach based on the analysis of sediment characteristics, sedimentary charcoal, organic matter and pollen, as well as historical sources. This multi-proxy research permits high resolution palaeoenvironmental and fire history reconstruction of a mountain area located in the southern central Pyrenees (Spain). In the Pyrenees, fire is typically attributed to human activities since the beginning of the Bronze Age and may be correlated with slash-and-burn cultivation, metallurgy and pasturing activities. The data indicate a good linkage between high fire signals and Poaceae and Cerealia pollen, which reveals the impact of agro-pastoral practices. This study also shows two periods, 2900–2650cal yr BP and 1850–1550cal yr BP, for which higher frequencies of fire occurred, suggested by high arboreal pollen (AP) concentrations, and confirming the need for arboreal biomass to sustain fires. From the beginning of the Middle Ages, it seems that a change occurred in the anthropogenic use of fire, from a tool for agro-pastoral forest clearance to a means of maintaining open spaces. [Copyright &y& Elsevier]

Abstract: The effects of fertilization, pasture sowing and tree plantation on soil fertility and tree and pasture production can vary depending on the soil type. Tree plantation is recognized as a way to reduce nutrient leaching and increase land profitability in agronomic and forest soils, meanwhile pasture fertilization and sowing is usually associated to better pasture productivity and quality. Fertilization can be performed with mineral fertilizers, which have become expensive in recent times, or with organic fertilizers like sludge, which is being promoted worldwide. This study aims to evaluate the effects of sludge fertilization, tree planting and pasture sowing on different variables of soil (KCl-pH, cation exchange capacity, total N, total and Mehlich P, nitrate and soil organic matter) and pasture (production, botanical composition, crude protein and P concentration) in treeless and agroforestry systems established in forest and agronomic soils. The experimental design was a randomized block following an incomplete factorial design with three replicates and nine treatments including two types of soils (forestry and agronomic), two types of vegetation (natural and sown), two types of fertilization (sludge fertilization and mineral fertilization, with a no fertilizer control) in afforested and treeless pastures. Pasture production and quality was better under agronomic soils, which also had higher levels of KCl-pH, cation exchange capacity, nitrate, total N and P than forest soils. Tree establishment did not modify nitrate or P leaching, probably due to the youth of the trees when most of nitrate was leached at the beginning of the experiment, but reduction of soil KCl pH and pasture crude protein was found in forest soils, when trees and pasture were together established, probably due to the high extractions of these systems compared with unsown forests. Moreover, the sludge inputs increased pasture production better than the mineral fertilizer in the forest soils, probably due to the greater amount of nutrients applied by the former. Sowing enhanced the presence of sown grasses in the forest understory, but their presence reduced pasture quality, and they disappeared within a short period of time. Therefore, the use of the sludge as fertilizer allows nutrient recycling of this residue in soils of low fertility and increases productivity and preserves fertility compared with mineral fertilizer at short (forest soils) and medium (agronomic soils) term. [Copyright &y& Elsevier]

[Display omitted] • Vegetation shifts in Mediterranean alpine ecosystems strongly impact SOM dynamics. • Soil aggregation is controlled by changes in soil microbial community structure. • Increased tree cover negatively impacts microaggregate stability. • Forest vegetation promotes the formation of macroaggregates. Afforestation and subsequent expansion of trees on former grasslands may significantly impact the structure and activity of the soil microbial community, altering soil aggregation and affect its potential to store and cycle organic matter (OM). We investigated OM dynamics in aggregate-size topsoil samples collected along a Mediterranean alpine ecotone consisting of three vegetation types (grassland/shrubland, mixed shrubland-pine, and pine forest) in central Spain. Analytical determinations of soil organic carbon (SOC), total nitrogen (TN), particulate OM (POM), mineral-associated OM (MaOM), and the stable isotopic composition of carbon were conducted in each of the four aggregate-size fractions considered. Additionally, the structure of the microbial community (assessed as PLFA abundance), and the β-glucosidase and β-glucosaminidase activities were determined in bulk soil samples. More than half of the soil mass was contained within small macroaggregates regardless of vegetation type. SOC and TN values increased with decreasing aggregate-size classes across all vegetation types. The stability of microaggregates was negatively affected by the expansion of woody vegetation, which resulted in tree-dominated stands showing comparatively lower SOC and TN values in the smaller aggregate-size classes. On the other hand, these vegetation dynamics promoted soil macro-aggregation. While SOC contents did not show significant differences between land covers, vegetation shifts induced changes in the soil microbial community. Soil δ13C values, the abundance of gram-positive bacteria and β-glucosidase activity were significantly higher in grasslands/shrublands than in forests, while significantly higher fungi/bacteria ratio was observed in forests. Small macroaggregates appear to play a key role in the stabilisation of relatively unprocessed OM across all vegetation types, as suggested by their significantly higher concentrations of POM. However, this fraction represents the most labile pool of OM, and as such, it is the most exposed to mineralisation. We conclude that the afforestation and potential vegetation shifts experienced in Mediterranean alpine grasslands lead to distinct changes in soil microbial communities, aggregation and soil OM dynamics, which given the strong temperature sensitivity to decomposition commonly reported in cold environments, suggests that soil OM in these high-elevation ecosystems may become highly vulnerable to environmental change. [ABSTRACT FROM AUTHOR]

Abstract: Spatial distribution patterns of epibenthic communities on the Galician continental shelf were studied using multivariate methods. Data came from 5 surveys carried out in 2002, 2003 and 2004. Beam trawls and otter trawls were used to study epibenthic communities along 8 transects perpendicular to the coastline. The role of depth, season, latitude and sediment characteristics was examined. Seven habitats were described according to bathymetry and sediment characteristics. There were weak linear relationships between environmental variables and species richness, biomass and species diversity. However, the canonical analysis showed that depth and sediment characteristics greatly influence smaller epibenthic communities sampled by beam trawl. Six assemblages were obtained for beam trawls: inner shelf mud, very fine sands, and fine sands, middle shelf sands, and outer shelf very fine sands, and fine sands. Five assemblages were identified for larger-sized and swimming epibenthos sampled with otter trawls. These assemblages were also determined according to depth and sediment type but sediment characteristics were less important. Otter trawl assemblages were the same as the beam trawl ones, except for on the outer shelf where no differences between sediment type were detected. For both gears, inner and outer shelf assemblages displayed a higher biotic variability than the middle shelf, as a consequence of a higher environmental heterogeneity. Typifying species were mainly eurytopic in the middle shelf, whereas eurytopic and stenotopic species characterised the inner and outer shelves. [Copyright &y& Elsevier]

Abstract: Quick overland flow peaks observed in runoff hydrographs from rainfall experiments carried out on mica schist soils in Rambla Honda (SE Spain) suggest development of soil water repellency (SWR). In order to spatially characterize its occurrence and severity and the factors controlling it, potential water repellency was measured in 120 soil samples using the WDPT test at laboratory conditions. Actual water repellency measurements were additionally performed at field conditions in order to increase our knowledge about the occurrence of this phenomenon. Samples were taken in bare soils (n = 23), beneath plant clumps of Retama sphaerocarpa (n = 23) and Anthyllis cytisoides (n = 10) and from soils affected by rabbit latrines (n = 9). Soil organic matter was also determined in 47 selected samples with a broad range of potential water repellency values. Results indicate that occurrence of SWR in Rambla Honda (potential water repellency values) varies in the three soil dimensions, areal and depth. The areal variation is due to the patchy pattern of organic matter and the variation with depth of the washed-in layer of sieving crusts developed in colluvial and alluvial soils after abandonment by agriculture. These layers act as physical barriers that restrict or impede the translocation of hydrophobic compounds to deeper layers. Such three-dimensional heterogeneity stresses the importance of the sampling scheme used for adequate SWR assessment. The severity of water repellency is generally reduced in this area because of the relatively scarce organic matter content and its spatial variability. A weak exponential relationship was found between the severity of potential water repellency and total organic carbon (r 2 = 0.38; p-value < 0.01). Extreme values of actual and potential water repellency were found in rabbit latrines, stressing the importance of macrofauna in its development. Water repellency has an important impact on the local hydrology controlling runoff–runon between vegetated and bare patches, and possibly flash flooding during heavy rains in early autumn or after long dry periods. Review of a series of runoff hydrographs from previous rainfall simulations has distinguished four types of runoff patterns based on the occurrence of SWR. [Copyright &y& Elsevier]

This article presents a study about soil degradation in Central Spain. It discusses that the soil degradation is caused by sheet water erosion by low-intensity rainfall events. The results of the study shows that the organic matter content lost in the sediment which is six times more than in the soil is a permanent loss that threatens the development of the surface of the soil when the vegetative cover is less than 40 percent, even though the amount of soil lost is relatively insignificant from a quantitative standpoint.

In this study, we evaluated the amount of accumulated solids in six different horizontal subsurface flow constructed wetlands (SSF CWs). We also investigated the relationship between accumulated solids and, on one hand, the wastewater quality and load and, on the other hand, the hydraulic conductivity of the granular medium. Aerobic and anaerobic biodegradability tests were also conducted on the accumulated organic matter. Experiments were carried out on full scale wastewater treatment systems consisting of SSF CWs with stabilisation ponds, which are used for the sanitation of small towns in north-eastern Spain. There were more accumulated solids near the inlet of the SSF CWs (3–57kg dry matter (DM)/m2) than near the outlet (2–12kgDM/m2). Annual solids accumulation rates ranged from 0. 7 to 14. 3kgDM/m2 year, and a positive relationship was observed between accumulation rates and loading rates. Most of the accumulated solids had a low level of organic matter (). The results of the aerobic and anaerobic tests indicated that the accumulated organic matter was very recalcitrant and difficult to biodegrade. The hydraulic conductivity values were significantly lower near the inlet zone (0–4m/d) than in the outlet zone (12–200m/d). Although hydraulic conductivity tended to decrease with increasing solids accumulation, the relationship was not direct. One major conclusion of this study is that the improvement of primary treatment is necessary to avoid rapid clogging of the granular media due to solids accumulation. [Copyright &y& Elsevier]

The use of cannery wastewater for irrigation represents a prime solution in the optimization of water resources in semi-arid areas. However, the environmental risks associated to this practice must be evaluated in detail. Soil quality could be affected as a result of the addition of organic residues and some salts and electrolytes to the soil. We evaluated soil aggregation status and organic matter dynamics in three semi-arid agricultural soils in northeast Spain before and after four years of irrigation trials in order to asses the effect of wastewater irrigation on soil physical status. Aggregation indexes (mean weight diameter, dispersible clay), particulate organic matter abundance, fine sand-size organic matter and carbon (C) linked to the mineral fraction were used as soil quality indicators and quantified before and after four years of trials. Four irrigation treatments (‘clean’ control, two blends of waste and wastewater, and waste water) were applied to three different sites to supply crop water needs. The water application methods, crops and land management varied between sites. A permanent alfalfa crop was planted under sprinkler irrigation on a Xeric Petrocalcid and a Xeric Haplogypsid. A crop rotation (corn, wheat, barley, sunflower) was implemented under flooding irrigation on a Typic Xerofluvent. We speculated that aggregation could be improved as a consequence of the addition of fresh organic residues. However, the simultaneous addition of dissolved salts could counteract for this effect and in fact lead to a destabilization of soil structure. Results differed for different soil characteristics (particle-size distribution, gypsum content) and management regimes. Changes in aggregation and/or organic matter fractions were observed in the non- gypsic soils. These changes were due to soil management and properties and were not affected by the application of wastewater. The addition of organic solids in suspension led to a proportionate increase in labile organic matter in the gypsic soil. This had no effect on soil aggregate stability, which was mostly dominated by soluble calcium. Our study illustrates the absence of negative effects of irrigation with cannery wastewater on soil physical status and organic fractions in any of the three studied semi-arid Mediterranean soils. [ABSTRACT FROM AUTHOR]

Abstract: Under semi-arid conditions, the properties of many soils are influenced by the presence of organic matter and calcium carbonate (CaCO3). However, the influence of different tillage systems on the development of these properties has scarcely been studied under semi-arid Mediterranean conditions. We studied the effect of long-term conservation tillage (CT) and traditional tillage (TT) on the stratification ratio of soil organic carbon and on CaCO3 content. The study was conducted in a wheat (Triticum aestivum L.)–sunflower (Helianthus annuus L.) crop rotation established in 1991 under rainfed conditions in Southwestern Spain. As is traditional in this area, wheat was fertilised, but sunflower was not. Conservation tillage was characterised by reduced number of tillage operations and leaving crop residues on the soil surface, while TT was with mouldboard ploughing. Stratification ratio of soil organic C was calculated from C contents in the 0–5 and 5–10cm soil layers divided by that in the 25–40cm. Stratification ratio of soil organic C under the CT (>2) was significantly greater than under TT (<2); values >2 indicating better soil quality. Our results show a loss of CaCO3 under both tillage systems. However, the loss of CaCO3 was significantly higher under TT than under CT. Also, P and K accumulated in the soil surface and stratification ratio for both nutrients was greater in CT than in TT. [Copyright &y& Elsevier]

Abstract: A 2800m deep station was sampled on three occasions, in January 1999, June 1999 and April 2000, in the lower part of Cap-Ferret Canyon (Bay of Biscay). This area is characterised by a rapid accumulation of fine-grained sediments and by important inputs of reworked organic matter in an intermediate state of decay. Diagenetic reactions within the sediment follow the well-established depth sequence resulting from the oxidation of organic deposits by different electron acceptors. At our station, live benthic foraminiferal faunas differ strongly from faunas previously collected at nearby open slope sites at a comparable water depth. Spectacularly high densities of deep infaunal species are observed in the deeper parts of the sediment for all three sampling periods. In our opinion, these high deep infaunal densities are a direct response to the massive flux of partially degraded organic matter, which is slowly introduced into the deeper parts of the sediment, where it induces a rather stable succession of redox gradients. Melonis barleeanus lives in the dysoxic part of the sediment whereas Globobulimina affinis appears preferentially close to the zero oxygen boundary. Both taxa occupy niches where the highest content of Mn (III, IV)-oxides and -oxihydroxides and Fe (III)-oxides are recorded. The fact that most of the geochemical reactions within the sediment are directly or indirectly catalysed by heterotrophic and chemolithoautotrophic bacterial consortia could suggest that deep infaunal foraminifera may be highly specialised protozoans able to feed on, or live in symbiosis with these prokaryotic communities. [Copyright &y& Elsevier]

Twenty-one samples of winery and distillery effluents were collected from different Spanish winery and distillery industries. Electrical conductivity, pH, redox potential, density, organic charge (chemical oxygen demand, biological oxygen demand, total, volatile and suspended solids, oxidisable organic C and polyphenols) and contents of plant nutrients and heavy metals were analysed. The aim of this work was to study the composition of these effluents and to find relationships which would make it possible to use easily determined parameters to estimate their composition. The winery wastewater (WW) and vinasse (V) showed an acidic pH, a high organic load and notable polyphenol, macronutrient, micronutrient and heavy metal contents. Some of these properties are not compatible with agricultural requirements; therefore, conditioning treatment of these liquid wastes is necessary to produce a safe, stable and easily manageable end product. Generally, in both effluent types, significant correlations were found between easily analysable parameters, such as suspended, volatile and total solids, pH, electrical conductivity, density and redox potential, and most of the parameters studied. The linear regression equations obtained permitted an immediate characterisation of the WW and V samples using these parameters. [ABSTRACT FROM AUTHOR]

Floodplain forests are generally areas of high plant diversity compared with upland forests. Higher environmental heterogeneity, especially variation in belowground properties may help explain this high diversity. However, there is little information available on the spatial scale and pattern of belowground resources in floodplain forests. Geostatistics and coefficient of variation (CV) were used to describe the spatial variability of 20 soil properties ranging from essential plant nutrients, such as NH4 or PO4, to nonessential elements like Ti or V. The spatial variation of Si-to-(Al + Fe) ratio, an index of soil development, was also analyzed. Semivariograms and maps of selected properties were used to discriminate between the effect of flooding (and other mechanisms that may contribute to large scale trends in data) and local heterogeneity. The hypothesis that elements mainly cycled through biological processes (such as N) show different spatial properties than elements cycled through both biological and geological processes (such as P) or elements under strict geological control (such as Ti or V) is also presented. Redox potential was the most variable property (CV = 1.35) followed by mineral N, phosphate, organic matter, and carbon. Nonessential elements for organisms such as Si, Al, Ti, Rh, or V were less variable, supporting the hypothesis that biological control on soil properties leads to higher spatial variability. The range (the average distance within which the samples correlate spatially) varied between 3.89 m for water content to 18.5 m for the Si-to-(Al + Fe) ratio. The proportion of the total variance that can be modeled as spatial dependence (structural variance) was very variable, ranging between 0.34 for Fe and 0.96 for K. The addition of the large trend had a strong influence on the CV of most soil variables and created a gradient in C accumulation and the mineral weathering rate. The results suggest that flooding and other processes that are responsible for large spatial trends in the floodplain forest differentially affect biologically and geologically controlled variables with different turnover rates, thus providing a heterogeneous edaphic environment. [ABSTRACT FROM AUTHOR]

Chemical analyses and radioecological methods were combined in order to estimate the sediment accumulation rate in the upper 20 cm depth of the Palmones River estuary. Organic matter, total carbon, C:N and 137Cs vertical profiles showed changes at 13 cm depth. These changes could be associated with the decrease in river input since 1987 when a dam situated in the upper part of the estuary started to store water. Using 1987 as reference to date the sediment, accumulation rate was 1.2 cm yr−1. As alternative method, two layer model of 210Pbxs vertical distribution showed a sedimentation rate of 0.7 cm yr−1 with a surface mixing layer of 7 cm thickness.The high ammonium, potassium and sodium content in pore water and the strong correlation between 137Cs activities and organic matter in dry sediment suggests that 137Cs (the only anthropogenic product detected) is mainly accumulated in the estuary associated with the particulate organic material from the catchment area. [Copyright &y& Elsevier]

The concentrations of o-phosphate and dissolved inorganic carbon were monitored in the interstitial water of the sediment in two highly eutrophic coastal lagoons, Laguna Honda and Laguna Nueva (SE, Spain) from July 2000 to August 2001. Additionally, the organic matter concentration and the P-fractions in the sediment were analysed. Despite their proximity, these two lagoons showed many significant differences (P<0.05). The P-concentration in the interstitial water of the top sediment was higher in the Laguna Honda (up to 1 mg l-1), especially during summer, when both sites registered their highest values. By contrast, the concentration of organic matter and organic P-fractions were higher in the sediment of the Laguna Nueva. The concentration of the organic matter in the vertical profile of the sediment decreased with depth in the Laguna Nueva (from 17% at 0 cm to 7% at 15 cm, annual mean value) while it increased in the sediment of Laguna Honda (from 9% at 0 cm to 12% at 15 cm, annual mean value). The P-concentration in the interstitial water and the organic matter in the top sediment of Laguna Honda followed a seasonal pattern and, were both correlated with the temperature of the bottom water (r=0.706, P<0.05 and r= -0.929, P<0.01, respectively). The inorg-P fractions comprised 63% of the Tot-phosphate in the sediment of Laguna Honda, whereas org-P fractions (68%) dominated in the sediment of Laguna Nueva. The concentrations of Tot-P in the sestonic material collected at three different depths of the water column averaged 2.2 mg g-1d.w. in Laguna Honda and 2.5 mg g-1d.w. in Laguna Nueva. The average atomic C:P ratio of the sestonic material was significantly higher in Laguna Honda than in Laguna Nueva, but the top sediment in Laguna Nueva had a C:P ratio significantly higher than that of the sestonic material (average: 416 and 162, respectively).The different biodegradability of the organic matter in the top sediment probably explained the differences found in sediment composition between these two lagoons. We suggest that the P-reclying from the sediment to the interstitial water was faster in Laguna Honda due to the higher biodegradability of the organic matter. By contrast, the lower biodegradability of the organic matter in the top sediment of Laguna Nueva was probably due to a higher contribution of vascular plants which could explain the organic matter accumulation detected in this lagoon. [ABSTRACT FROM AUTHOR]

In this study, the early Pliocene palaeoenvironmental context of the Mediterranean Almería-Níjar Basin (SE Spain) is analysed using benthic foraminifera, with special focus on environmental conditions after the Messinian Salinity Crisis (MSC). A deep upper-slope setting (274 m water depth), with high oxygen levels and low organic matter fluxes, is inferred for the earliest Pliocene sediments over the Miocene-Pliocene boundary. In this setting, the westernmost and earliest recolonization of the species Siphonina reticulata across the Mediterranean is reported. This finding, along with the presence of intensively bioturbated sediments and highly diverse benthic foraminiferal assemblages at —or just above— the Miocene-Pliocene boundary might indicate the earliest establishment of well-ventilated fully marine conditions in the Mediterranean after the MSC. Subsequent shallowing from 274 to 220 m water depth during the earliest Pliocene is likely related to a global sea-level drop. Palaeobathymetry remains stable around 220–230 m water depth after this sea-level fall. However, three successive palaeoenvironmental subintervals could be defined within this upper slope setting. Increasing continental organic matter and sediment inputs indicate higher fluvial discharge during the first subinterval. The second subinterval records a decrease in both terrestrial organic matter and sediment supply due to lower riverine discharge. Finally, reduced input of continental organic matter suggests low river runoff during the third subinterval, in which a slight increase in transported shelf foraminiferal taxa may be related to vertical tectonic movements of the basin margins. • Post Messinian salinity crisis environment was a well-ventilated upper slope (274 m). • The westernmost, earliest Mediterranean recolonization of S. reticulata is reported. • This study presents the earliest post-Messinian establishment of marine conditions. • Infaunal and transported shelf taxa characterized three environmental subintervals. [ABSTRACT FROM AUTHOR]

Intensive greenhouse vegetable production is one of the most important economic activities in south-east Spain. Agricultural intensification has limited the application of organic matter (OM) in favor of synthetic chemical fertilizers, leading to altered soil microbial communities and production loss. We addressed the effects of soil microbial communities on plant productivity depending on different soil management practices in greenhouse agriculture. Greenhouse managements were i) conventional (i.e., with addition of synthetic chemical fertilizers) without organic amendments (CM), ii) conventional with organic amendments (CMOM) and with addition of synthetic chemical fertilizers, and iii) organic management with annual organic amendments and with no synthetic chemical fertilizer addition (ORG). We extracted soil microbial communities from five greenhouses per management type, added these inocula to pots with sterile substrate (peat:sand), and seeded disinfected tomato seeds. Plants grew for 2 months without nutrient addition (only water irrigation). Immediately prior to the end of the study, we measured photosynthetic rate, plant growth, and leaf functional traits. At the end of study, pot substrates inoculated with i) ORG soil communities had higher bacterial abundance (qPCR) compared to microbial communities inoculated with CM extracts; and ii) prokaryotic communities of CM and CMOM substrates differed in composition. Besides, substrates inoculated with CM inocula were significantly associated with the presence of a potential fungal pathogen. Plants inoculated with extracts from organic greenhouses grew more and had a higher photosynthetic rate than plants receiving soil microbial extracts from greenhouses with conventional management. There were differences in the NO 3 −, total N and organic matter contents of substrates between treatments at the end of the study, but not at the beginning of the study, suggesting differences in microbial activity between treatments. Although substrate N content differences did not translate into differences in leaf N, leaf δ 15N differed between treatments, indicating that the source of the soil microbial inocula influenced the N compound used by the tomato plants. Overall, this study suggested that soil microbial communities from organic greenhouses had a positive effect on crop productivity in intensive greenhouse agriculture. [ABSTRACT FROM AUTHOR]

Clay mineralogical and geochemical analyses (δ18O carb , and paired carbonate and organic matter carbon isotope), completed by the characterization of organic matter, have been performed on the Pliensbachian sediments exposed on the Rodiles section (Asturian Basin, Northern Spain). The objectives were to precise the Pliensbachian climate evolution at a relatively low paleolatitude of the Tethyan domain by comparison with previously published high-resolution clay mineralogical and geochemical data from the NW Tethyan domain (e.g. Paris Basin and Cardigan Bay Basin, West Wales). The clay mineral assemblages are dominantly composed of illite and illite-smectite mixed-layers (I–S) associated with minor proportions of chlorite and kaolinite. Smectites are not identified what may result either to their absence at the time of sedimentation or to their progressive illitization due to the burial diagenesis. Rock-Eval data show that organic matter reaching more than 5% in black-shale horizons is thermally mature with T max comprised between 444 and 454 °C indicating that the section is in the oil window and that the burial temperature reached or exceeded 80–90 °C. The low δ18O bulk values comprised between −3 and −6‰ clearly results from a diagenetic influence (thermal effect due to burial) but their fluctuations compared with δ18O measured on well-preserved belemnites guards show that the overall trend is however preserved. By comparison with higher latitude sedimentary basins, the most striking feature is the very small proportions of kaolinite (generally less than 5% while the proportions of this mineral reach 40% at higher paleolatitudes), except at the Pliensbachian/Toarcian transition, where the proportion of kaolinite increases significantly. Clay minerals likely originated from the erosion of the Iberian Massif located to the South of the Asturian Basin in a semi-arid climatic belt. This may explain the scarcity of kaolinite by comparison with sedimentary basins located at higher latitude influenced by more humid climate. The increasing proportions of kaolinite by the end of the Pliensbachian suggest southward expansion of the humid belt as a consequence of cooler temperatures and the establishment of steeper latitudinal gradients of temperature likely resulting from the formation of restricted polar ice cap. The main δ13C (on both 13C inorg and 13C org) Pliensbachian excursions including the negative excursion of the Sinemurian/Pliensbachian Boundary Event (SPBE) and the Late Pliensbachian positive excursion are well recognized. • Clay mineralogy and organic matter maturity indicate that the Rodiles section reached the oil window and a maximum burial temperature around 80–90 °C. • Despite the diagenetic influence, the scarcity of kaolinite suggest that a semi-arid climate prevailed over the Iberian massif. • Southward shift of the humid belt due to steeper latitudinal gradients of temperature by end of the Pliensbachian. [ABSTRACT FROM AUTHOR]

Analyses of X-ray microfluorescence (XRF) elemental maps of the ichnofossil assemblages from the upper Pliensbachian-lower Toarcian marl-limestone rhythmite of the South Iberian Palaeomargin (Betic Cordillera, SE Spain) show that the compositions of burrow infills are geochemically and mineralogically different with respect to the surrounding sediment. XRF elemental maps and back-scattered electron images show pyrite framboids within the burrows and enrichment in Fe and S relative to the host sediment. This is congruent with the position of burrows beneath the redox boundary at the time of their active or passive sedimentary infilling. Organic matter that accumulated at the seafloor was not preserved due to oxidation and consumption by benthic organisms. However, burrows located beneath the redox boundary served as traps for organic matter preservation. The composition of burrow fills reflects the original signal of the redox conditions of pore-waters below the sediment-water interface, which was not preserved in the surrounding sediment. The XRF elemental maps also show that some trace fossils from limestone and marly-limestone intervals contain high concentrations of Si, Al, K, Zn, Cr, and Ti with respect to the surrounding sediment. This may reflect enrichment of clay minerals in the burrow fills derived from overlying marly layers. This work proposes the use of elemental imaging of trace fossils prior bulk-rock geochemical analyses in order to evaluate the potential for biogenic heterogeneity and elemental partitioning before sampling. Geochemical analysis of trace fossils represents an additional tool that may be of use in hydrocarbon exploration. • XRF compositional maps show geochemical differences between burrows and host sediment. • BSE images show relatively high content of pyrite and organic matter within burrows. • Environmental conditions for preserving OM were better within burrow galleries. • Burrow-water reducing conditions acted as traps for organic matter preservation. • Compositional maps are useful for testing geochemical heterogeneity in bioturbated rocks. [ABSTRACT FROM AUTHOR]

This study aims to determine aluminum fractions in the fine earth of acidic soils under different land uses (forest, pasture and cultivation) and in the river bed sediments of the headwater of the Mero River in order to identify and quantify Al-bearing phases to assess Al mobility and potential bioavailability (environmental availability) in the monitoring area. Sequential extraction is used to evaluate the Al partitioning into six fractions operationally defined: soluble/exchangeable/specifically adsorbed, bound to manganese oxides, associated with amorphous compounds, aluminum bound to oxidizable organic matter, associated with crystalline iron oxides, and residual fraction (aluminum within the crystal lattices of minerals). The mean concentration of total aluminum (24.01 g kg -1 ) was similar for the three considered uses. The mean percentage of the aluminum fractions, both in soils and sediments, showed the following order: residual fraction ≫ amorphous compounds ≈ crystalline iron oxides > water-soluble/exchangeable/specifically adsorbed > bound to oxidizable organic matter ≈ Mn oxides. However, in the soils, the amorphous compounds and water-soluble/exchangeable/specifically adsorbed fraction showed considerable differences between some types of uses, the percentage of aluminum linked to amorphous compounds being higher in forest soils (16% of total Al) compared to other uses (mean about 8% of total Al). The highest values of water-soluble/exchangeable/specifically adsorbed Al were also found in forest soils (mean 8.6% of the total Al versus about 4% of pasture and cultivation), which is consistent with the lower pH and higher organic matter content in forest soils. Nevertheless, the potentially bioavailable fraction (sum of the first three fractions) is low, suggesting very low geoavailability of this element in both soils and sediments; hence, the possibility to affect the crops and water quality is minimal.

Water abstraction is a prevalent impact in streams and rivers, which is likely to increase in the near future. Because abstraction reduces discharge, the dimensions of the wetted channel and water depth and velocity, it can have strong influence on stream ecosystem functioning. Although the impacts of large dams on stream and river ecosystems are pretty well known, the effects of diversion schemes associated with low dams are still poorly understood. Furthermore, the remote location of many diversion schemes and the lack of collaboration by power companies often make it difficult to know the volume of water diverted and its environmental consequences. To assess the impact of water abstraction on the storage and breakdown of coarse particulate organic matter in streams we compared reaches upstream and downstream from five low dams that divert water to hydropower plants in mountain streams in N Spain. We measured the storage of organic matter and the breakdown of alder leaves in winter and spring, and calculated the results at the patch (i.e., per square meter of bed) and at the reach scale (i.e., per lineal meter of channel). Water diversion significantly reduced discharge, and the width and depth of the wetted channel, but did not affect water quality. Diversion significantly reduced the storage and breakdown of organic matter in winter but not in spring. The number of shredders colonizing litter bags was also significantly reduced. The results point to an important effect of water abstraction on the storage and breakdown of organic matter in streams at least in some periods, which could affect downstream reaches, global carbon fluxes, and associated ecosystem services., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Sustainable management of forest resources, including nutrient retention and protection of the soil structure, is required to ensure long-term soil fertility and productivity of later rotations. Potential depletion of soil nutrients is particularly likely in production systems based on fast-growing trees, such as eucalypts. We have studied production of second rotation Eucalyptus globulus stands at two sites in northern Spain and two in central Portugal, after replanting or coppicing, under four treatments, in which plant residues from the firstcrop were utilised. The residues were either removed from the sites (Treatment R), spread over the soil surface (Treatments S, uniform spreading, and W, in which the woody debris was confined to rows between the trees) or incorporated into the soil by harrowing to 15-cm depth (Treatment I). We measured tree height and girth at intervals over three growing seasons, and root biomass at the Portuguese sites. Decomposition of three residue components: leaves-plus-bark, twigs and branches, was measured in litter bags placed in the position corresponding to the placement of the organic residues. By the end of the experiment, tree height was significantly greater in Treatment I than in Treatment R at both Spanish sites, if planted as seedlings, with intermediate growth in S and W. In Portugal, tree height was smaller in R,though not significantly. DBH showed similar trends, although treatment differences were not significant. Coppiced trees grew faster thanseedling trees, but a significant treatment effect on the growth wasonly observed at the inland Portuguese site, where it was better in Treatment I by the end of the experiment. The residues decomposed significantly faster in I than S or W at the Portuguese sites, but not in Spain. Leaves-plus-bark decomposed faster than twigs, and twigs faster than branches. The results are discussed in relation to recommended management options. [ABSTRACT FROM AUTHOR]