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Geochemical, geological and hydrological influence on ostracod assemblages distribution in the hyporheic zone of two Mediterranean rivers in central Spain
No full textOn the catchment spatial scale, rivers can be considered a patchy discontinuity from
headwaters to mouth with significant implications on the structure and functioning of the
hyporheic zone (HZ) biota. The present study aims to determine the spatial variation of
ostracod assemblages from a fluvial HZ of two groundwater-fed rivers of the Jarama basin
(Central Spain). We hypothesised that ostracod abundance and composition are subject to
changes in water condition, substratum type geology and surface water/groundwater
exchanges along the hyporheic flow path. Individual measures of 29 physico-chemical
parameters, water discharge, sediment size and sediment organic matter (as loss of ignition)
were measured at a depth of 20–40 cm at 20 hyporheic sites of the Henares and Tajuña
Rivers. The results show that factors like elevation, carbonate water type, high permeable
riverbed substratum and groundwater upwelling at headwaters contribute to shape a diverse,
mixed assemblage formed by stygophyle and stygoxene ostracods (14 species). Conversely,
low-mineralised waters, siliceous riverbeds with poor permeability, and relatively low surface/
ground water exchanges in the middle and lower sectors, limit species diversity and ostracod
abundance to exclusively stygoxene elements (nine species). Ostracod abundance
correlates positively with fine sands (0.125–0.25 mm) (Spearman, r¼0.70), and negatively
with temperature (r¼�0.40), SO4
2� (r¼�0.45) and Mg2þ (r¼�0.40). Trace metal (Cu, Mn,
Ni) accumulation in the intermediate and lower sectors of both rivers appears harmful for
Ilyocypris brady (r¼�0.46) and Pryonocypris zenkeri (r¼�0.40), whereas As relates
negatively to the abundance of Candona candida (r¼�0.51), Pryonocypris zenkeri
(r¼�0.60) and Herpetocypris brevicaudata (r¼�0.72). The results highlight the significance
of recent ostracods as a proxy to assess the water conditions in a HZ and to provide
forthcoming approaches to depict surface-subsurface hydrological exchanges
Validation and scale dependencies of the triangle method for the evaporative fraction estimation over heterogeneous areas
No full textRemote sensing has proved to be a consistent tool for monitoring water fluxes at regional scales. The triangle method, in particular, estimates the evaporative fraction (EF), defined as the ratio of latent heat flux (LE) to available energy, based on the relationship between satellite observations of land surface temperature and a vegetation index. Among other methodologies, this approach has been commonly used as an approximation to estimate LE, mainly over large semi-arid areas with uniform landscape features. In this study, an interpretation of the triangular space has been applied over a heterogeneous area in central Spain, using Landsat5-TM, Envisat-AATSR/MERIS and MSG-SEVIRI images. Some aspects affecting the model performance such as spatial resolution, terrain conditions, vegetation index applied and method for deriving the triangle edges have been assessed. The derived EF estimations have been validated against ground measurements obtained with scintillometer on a winter crop field during 2010–2011. When working with large spatial windows, removing areas with different topographic characteristics (altitude and slope) improved the performance of the methods. In addition, replacing the typically used NDVI with Leaf Area Index enhances the performance of the triangle method allowing a better characterization of the wet edge. Finally, results showed a relatively good performance for the EF estimates, with an RMSE of 0.11, 0.15 and 0.23 and R2 of 0.77, 0.41, and 0.24 for Landsat, Envisat and MSG satellites respectively, showing a scale dependency on the accuracy
Characterization of environmental impact on resources, using strategic assessment of environmental impact and management of natural spaces of “Las Batuecas-Sierra de Francia” and “Quilamas” (Salamanca, Spain)
No full textA new procedure is proposed for joint strategic environmental assessment and environmental impact assessment using simultaneous characterizations in the protected natural area studied to analyse the importance and extent of the impact of human activities within this area on the various natural resources. GIS techniques were used to define territorial models, including environmental information criteria in thematic layers to facilitate environmental diagnosis in the early planning stages in the areas of concern or of higher quality for conservation at different working levels (municipal, district, provincial or national). Traditional conventional environmental impact assessment methods were improved, using spatial analysis to compare scenarios based on the spatial and temporal variability of the impacts identified and their evaluation. This method was applied to the natural space of Las Batuecas-S. de Francia and Quilamas, where in an initial stage the different anthropogenic activities (landfills, etc.) with the potential to cause direct (sewage waters, etc.) or indirect (leachate, etc.) impacts were identified, using checklists and double-entry matrices to analyse actions likely to cause impacts, developing the cartography and identifying environmental impacts potentially damaging to the natural environment. Next, thematic and interpretive mappings were drawn up (surface water quality, aquifer vulnerability to pollution and vulnerability to municipal solid waste) to assess the effects upon resources (water, soil, air, etc.). Finally, by overlapping the impact identification and vulnerability mappings (municipal solid waste, pollution of aquifers and surface water quality) the impact characterization mapping was obtained, showing the absorption capacity of the different sectors to help the responsible bodies set out preventive and/or corrective measures. The essence of this paper is, in methodological terms, its use of two methods simultaneously (strategic environmental assessment and environmental impact assessment) in a protected natural area, allowing it to be extrapolated to any area where territorial management and planning studies need to be carried out
Fate of para-toluenesulfonamide (p-TSA) in groundwater under anoxic conditions: modelling results from a field site in Berlin (Germany)
No full textThis article reports on a field modelling study to investigate the processes controlling the plume evolution of para-toluenesulfonamide (p-TSA) in anoxic groundwater in Berlin, Germany. The organic contaminant p-TSA originates from the industrial production process of plasticisers, pesticides, antiseptics and drugs and is of general environmental concern for urban water management. Previous laboratory studies revealed that p-TSA is degradable under oxic conditions, whereas it appears to behave conservatively in the absence of oxygen (O2). p-TSA is ubiquitous in the aquatic environment of Berlin and present in high concentrations (up to 38 μg L−1) in an anoxic aquifer downgradient of a former sewage farm, where groundwater is partly used for drinking water production. To obtain refined knowledge of p-TSA transport and degradation in an aquifer at field scale, measurements of p-TSA were carried out at 11 locations (at different depths) between 2005 and 2010. Comparison of chloride (Cl−) and p-TSA field data showed that p-TSA has been retarded in the same manner as Cl−. To verify the transport behaviour under field conditions, a two-dimensional transport model was setup, applying the dual-domain mass transfer approach in the model sector corresponding to an area of high aquifer heterogeneity. The distribution of Cl− and p-TSA concentrations from the site was reproduced well, confirming that both compounds behave conservatively and are subjected to retardation due to back diffusion from water stagnant zones. Predictive simulations showed that without any remediation measures, the groundwater quality near the drinking water well galleries will be affected by high p-TSA loads for about a hundred years
Effects of mixed solvents on the structural morphology and membrane distillation performance of PVDF-HFP hollow fiber membranes
No full textPoly(vinylidene fluoride-hexafluoropropylene), PVDF-HFP, hollow fiber membranes were prepared by the dry/wet spinning technique, maintaining all the parameters the same except the solvent used to prepare the polymer solution. Different solvents namely, single N,N-dimethyl acetamide (DMAC) and different mixed solvents, DMAC and trimethyl phosphate (TMP) as well as N,N-dimethyl formamide (DMF) and TMP were employed. The relative affinity of the PVDF-HFP and the solvent(s) and the thermodynamic and kinetic aspects responsible for membrane formation were investigated and related with the structure of the prepared hollow fiber membranes. The structural and morphological properties of the hollow fiber membranes as well as the necessary parameters to be known for a membrane proposed for direct contact membrane distillation (DCMD) were studied by different characterization techniques. It was observed that an increase of TMP ratio in the solvents mixture resulted in a decrease of the finger-like structure of the external layer, an increase of the pore sizes of the hollow fibers and the DCMD permeate flux enhancement as consequence. When changing DMAC by DMF a thicker hollow fiber membrane was obtained and the DCMD was decreased due partly to the formation of macro-voids in the middle layer of the hollow fiber membrane
Simultaneous screening of targeted and non-targeted contaminants using an LC-QTOF-MS system and automated MS/MS library searching
No full textSimultaneous high-resolution full-scan and tandem mass spectrometry (MS/MS) analysis using time of flight mass spectrometry brings an answer for increasing demand of retrospective and non-targeted data analysis. Such analysis combined with spectral library searching is a promising tool for targeted and untargeted screening of small molecules. Despite considerable extension of the panel of compounds of tandem mass spectral libraries, the heterogeneity of spectral data poses a major challenge against the effective usage of spectral libraries. Performance evaluation of available LC-MS/MS libraries will significantly increase credibility in the search results. The present work was aimed to evaluate fluctuation of MS/MS pattern, in the peak intensities distribution together with mass accuracy measurements, and in consequence, performance compliant with ion ratio and mass error criteria as principles in identification processes for targeted and untargeted contaminants at trace levels. Matrix effect and ultra-trace levels of concentration (from 50ngl(-1) to 1000ngl(-1) ) were evaluated as potential source of inaccuracy in the performance of spectral matching. Matrix-matched samples and real samples were screened for proof of applicability. By manual review of data and application of ion ratio and ppm error criteria, false negatives were obtained; this number diminished when in-house library was used, while with on-line MS/MS databases 100% of positive samples were found. In our experience, intensity of peaks across spectra was highly correlated to the concentration effect and matrix complexity. In turn, analysis of spectra acquired at trace concentrations and in different matrices results in better performance in providing correct and reliable identificatio
Drought management plans and water availability in agriculture: A risk assessment model for a Southern European basin
No full textTradeoffs in River Restoration: Flushing Flows vs. Hydropower Generation in the Lower Ebro River, Spain.
No full textAlthough the effectiveness of flushing floods in restoring basic environmental functions in highly engineered rivers has been extensively tested, the opportunity cost is still considered to represent an important limitation to putting these actions into practice. In this paper, we present a two-stage method for the assessment of the opportunity cost of the periodical release of flushing flows in the lower reaches of rivers with regimes that are basically controlled by a series of dams equipped with hydropower generation facilities. The methodology is applied to the Lower Ebro River in Spain. The results show that the cost of the reduced power generation resulting from the implementation of flushing floods is lower than the observed willingness to pay for river restoration programmes
Technical, financial and location criteria for the design of Land Application System Treatment
No full textConventional water treatments when downsized to cover the demands of small and scattered populations are costly and ineffective. In fact, many small towns cannot afford the high average treatment costs nor provide the skill and complex management requirements. Even when these facilities are available, waste water might not be properly treated. Land application system treatments (LAST) have been shown to be preferable on the basis of their technical effectiveness and financial viability. The recently approved Spanish regulations (RDL 1620/2007, pp 0369–50661) represent an opportunity for the implementation of well-designed LASTs. This paper presents an assessment methodology for the design of LASTs by combining technical, financial and location criteria. The method is applied to the design of LASTs to cover the water disposal demand of twelve municipalities located within the protected natural landscape, and surrounding areas of ‘El Rebollar’, Salamanca, Spai