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The conservation of submerged vegetation is crucial in the functioning of aquatic ecosystems. We have assessed, by means of subaquatic quantitative sampling transects, the current status of the hydrophytic flora in 14 lakes in the Lagunas de Ruidera Natural Park, a Biosphere Reserve site in central Spain, surrounded by a semi-arid landscape. The conforming lakes have endured several anthropic pressures for decades (e.g., eutrophication, land-use changes, etc.). By comparing the current with the former status (20 years ago) of hydrophytes in the natural park, substantial negative (species richness loss, decrease in submerged meadow coverage, particularly in the upstream lakes) and positive (natural recovery of meadows after the cut-off of sudden disturbances caused by point pollution sources, improving of trophic state in some lakes, no presence of exotic hydrophytes) changes in the lakes were noticed. We have analyzed that the disappearance of all the hydrophyte (mainly charophytes) stands would represent the loss of ecosystem services. For example, up to 70 t CH 4 might be released from the charophyte detritus, an internal pool of phosphorus (as high as 1400 mgP/m2) stored in the charophytes stands could be liberated. Some lakes require special measures, but overall, to preserve this lake complex, and other similar ones, we propose to study, in detail, the causes of submerged vegetation deterioration (focusing on the presence of pesticides –in water and sediments-, and other reasons) to assess the ecological risks, to protect the groundwater resources, preventing the lakes from receiving surficial point and non-point sources of pollution. [ABSTRACT FROM AUTHOR]

Nitrate pollution in aquifers is a global concern. Spain has developed a national strategy to recover nitrate polluted aquifers aligned with the European Union (EU) policies, specifically through the water planning under the EU Water Framework Directive. River basin management plans use PATRICAL model results to define the maximum nitrogen surplus in each polluted aquifer for the first time. The maximum nitrogen surplus allows to reach the good status in each aquifer and the model provides the number of years required. Around 30% of the aquifers in Spain is currently heavily polluted by nitrates. Model results show that 90% of these aquifers can be recovered in next 6–12 years by increasing nitrogen use efficiency and reducing nitrogen losses around 50%, which is in line with the EU Farm to Fork Strategy. The remaining aquifers require additional reductions to achieve the good status. In Spain this increase in nitrogen efficiency can be obtained with different measures including 30% reduction of current fertilization. [Display omitted] • Spanish strategy to recover nitrate polluted aquifers is perfectly aligned with the European Farm to Fork Strategy. • In Spain 30% of aquifers have high nitrate levels. • PATRICAL model results define maximum nitrogen surplus in each aquifer. • 90 % of groundwater can be recovered reducing nitrogen losses by 50%. • Recovery time required is between 6 and 12 years for most aquifers. [ABSTRACT FROM AUTHOR]

Leachates from intensive agriculture containing high nitrate have been identified as a major cause of the severe eutrophication crisis that impacts Mar Menor (SE Spain), the largest hypersaline coastal lagoon in the Mediterranean basin. A best management practice for removing NO 3 −-N is denitrifying bioreactors. This is the first study to assess the efficiency of citrus woodchips bioreactors in treating agricultural leachates that flow to the Mar Menor via surface discharges. Denitrification capacity, woodchip degradation (by weight loss), formation of potentially harmful compounds, and greenhouse gas (GHG) emissions were assessed. Three bioreactors (6 m × 0.98 m x 1.2 m) filled with citrus woodchips (3 m3 d−1 per bioreactor) through which the untreated ditch water over 1.5 years. Bioreactors were operated at 8 h, 16 h, and 24 h hydraulic residence time respectively, in each bioreactor. The main characteristics of the ditch water were: pH ≈ 7.5–8.0, electrical conductivity ≈ 5–8 dS m−1, dissolved organic carbon ≈6–10 mg L−1, and NO 3 −-N ≈ 22–45 mg L−1. Bioreactors were highly efficient in reducing NO 3 −-N. The average R NO3 in effluents was for the complete experimental period 8 g N m−3 d−1, 10.9 g N m−3 d−1, and 12.6 g N m−3 d−1 for 8, 16 and 24 h residence time, respectively. Nitrate reduction efficiency was modulated by seasonal changes in temperature, with an increasing efficiency in warmer periods (maximum ≈ 85–90% for all hydraulic residence time) and decreasing in colder ones (minimum ≈ 12%, 23% and 41% for hydraulic residence time 8, 16 and 24 h respectively). Woodchips degradation was greatest during the first six months (average ≈ 29% weight loss) in the material above the water level, attributable to aerobic mineralization of the organic carbon, while weight loss was ≈11% in woodchip media continuously below the water level. Dissolved organic carbon, sulfide, ammonium, and soluble phosphorus concentrations in the effluents were mostly low, although some peaks in concentrations occurred. Design consideration must be taken to avoid environmental impacts due to the occasional presence of harmful compounds in the effluents. [Display omitted] • Citrus woodchip bioreactors denitrified saline leachates with NO 3 −-N = 22–45 mg L−1 • Woodchip aging negatively affected nitrate removal particularly below ≈20 °C. • Sulfide, ammonium, and soluble phosphorus may appear in bioreactor effluents. • Higher CO 2 emissions and woodchips degradation occurred above the water level. • Woodchips continuously flooded had a higher production of N 2 O emissions. [ABSTRACT FROM AUTHOR]

The wine industry produces large quantities of wastewater that often contains high levels of organic matter and nutrients, like nitrogen and phosphorous. In particular, nitrogen pollution can be harmful, even at low levels, since infants are vulnerable to nitrates in drinking water, and excess nitrogen can harm the health of soils and waterways. Herein, an innovative compact, modular, and mobile treatment wetland (TW) using cork by product as the only granular media was used to treat the final effluents from the Codorniu winery (Sant Sadurní d'Anoia, Spain). The TW was operated during two 5-month periods with or without intermittent induced aeration (40 min cycles, 90 L/min air flow rate). Nitrate (N-NO 3) and total nitrogen (TN) removal were higher (52.8% and 46.8%, respectively, p < 0.05) during TW operation under aerated-condition. Additionally, q PCR analysis of 16S rRNA, nir S and nos Z genes revealed that intermittent induced aeration facilitates N-NO 3 reduction by the stimulation of denitrifying bacteria in the TW biofilm (11.4% increase in nir S copies number/g cork sample, p < 0.05) as well as increasing the number of heterotrophic bacteria adhered to cork (25.5% increase in 16S rRNA copies number/g cork sample, p < 0.05). Moreover, SEM images demonstrated the suitability of cork as a resistant filter media for TW after long-term system operation (1.5 years). In conclusion, our results suggest that aeration improved nitrogen compounds removal compared to the non-aerated period, without affecting phosphorous elimination. Additionally, residual cork is presented here in a circular bioeconomy view, as a suitable filling media to treat winery wastewater that can provide additional carbon source to increase C/N rate stimulating denitrification, as well as a reliable organic substrate for biomass growth. [Display omitted] • Cork filled TW could be an appropriate technology to treat and/or remediate winery wastewater with high nitrate content. • The induced aeration in a vertical TW using cork as filter medium showed higher removal rates for NO 3 -N and TN. • The saturated-aerated vertical TW increased microbial abundance with the presence of the denitrification genes nir S and nos Z. • The nir S genes showed higher relative abundance than nos Z. [ABSTRACT FROM AUTHOR]

Due to the agricultural practices in Spain, 13% of the entire territory has been declared as vulnerable to nitrate-polluted water. In order to mitigate the environmental impact caused by nitrogen, a hybrid system of artificial wetlands has been engineered thanks to the European project known as LIFE REAGRITECH. The prototype has been thought as a compact, modular, and portable system, automated and operated in a remote manner. Monitoring of the system will result in valuable knowledge for public management, farmers, researchers, and universities, and it will provide useful information intended to improve the decision-making process as a way of preserving water resources and environment. Project REAGRITECH offers significant future perspectives in the field of agriculture in Europe and in Colombia as well. [ABSTRACT FROM AUTHOR]

A strong normative development in Europe, including the Nitrate Directive (1991) and the Water Framework Directive (WFD) (2000), has been promulgated. The WFD states that all water bodies have to reach a good quantitative and chemical status by 2015. It is necessary to consider different objectives, often in conflict, for tackling a suitable assessment of the impacts generated by water policies aimed to reduce nitrate pollution in groundwater. For that, an annual lumped probabilistic model based on Bayesian networks (BNs) has been designed for hydro-economic modelling of groundwater quality control under uncertain conditions. The information introduced in the BN model comes from different sources such as previous groundwater flow and mass transport simulations, hydro-economic models, stakeholders and expert opinion, etc. The methodology was applied to the El Salobral-Los Lianos aquifer unit within the 'Easter Mancha' groundwater body, which is one of the largest aquifers in Spain (7,400 km2), included in the Júcar River Basin. Over the past 30 years, socioeconomic development within the region has been mainly depending on intensive use of groundwater resources for irrigating crops. This has provoked a continuous groundwater level fall in the last two decades and significant streamflow depletion in the connected Júcar River. This BN model has proved to be a robust Decision Support System for helping water managers in the decision making process. [ABSTRACT FROM AUTHOR]

Summary: Although the legislation on groundwater quality targets pollutant concentration, the effects of measures on non-point source pollution control are often evaluated in terms of their emission reduction potential at the source, not on their capacity of reducing the pollutant concentration in groundwater. This paper applies a hydro-economic modelling framework to an aquifer, El Salobral-Los Llanos aquifer (Mancha Oriental, Spain), where nitrate concentrations higher than those allowed by the EU Water Framework Directive and Groundwater Directive are locally found due to the intense fertilizer use in irrigated crops. The approach allows defining the economically optimal allocation of spatially variable fertilizer standards in agricultural basins using a hydro-economic model that links the fertilizer application with groundwater nitrate concentration at different control sites while maximizing net economic benefits. The methodology incorporates results from agronomic simulations, groundwater flow and transport into a management framework that yields the fertilizer allocation that maximizes benefits in agriculture while meeting the environmental standards. The cost of applying fertilizer standards was estimated as the difference between the private net revenues from actual application and the scenarios generated considering the application of the standards. Furthermore, the cost of applying fertilizer standards was compared with the cost of taxing nitrogen fertilizers in order to reduce the fertilizer use to a level that the nitrate concentration in groundwater was below the limit. The results show the required reduction of fertilizer application in the different crop areas depending on its location with regards to the control sites, crop types and soil–plant conditions, groundwater flow and transport processes, time horizon for meeting the standards, and the cost of implementing such a policy (as forgone benefits). According to the results, a high fertilizer price would be required to reduce nitrate concentrations in groundwater below the standard of 50mg/l. In this particular case, it is more cost-efficient to apply standards to fertilizer use than taxes, although the instrument of fertilizer standards is more difficult to implement and control. [Copyright &y& Elsevier]

Abstract: This paper describes an integrated application of classical hydrogeological methods and multi-isotopic methods (δ15N, , δ34S, , δ13C) to assess the fate of groundwater nitrate in the Osona area, declared vulnerable to nitrate pollution by the Catalan Government in 1998, where nitrate is derived from intensive pig farming activities. Previous studies, involving a small area, indicated the occurrence of denitrification processes and their relationship with pyrite oxidation [Vitòria, L., Soler, A., Canals, A., Otero, N., 2008. Environmental isotopes (N, S, C, O, D) to determine natural attenuation processes in nitrate contaminated waters: example of Osona (NE Spain). Appl. Geochem. 23, 3597–3611]. For the present study, groundwater samples were collected at 60 production wells at three different periods between April 2005 and May 2006 to confirm that denitrification takes place in a larger area than that studied by Vitòria et al. [Vitòria, L., Soler, A., Canals, A., Otero, N., 2008. Environmental isotopes (N, S, C, O, D) to determine natural attenuation processes in nitrate contaminated waters: example of Osona (NE Spain). Appl. Geochem. 23, 3597–3611]. The aim of the study was to characterize the denitrification processes that control natural attenuation and to study their spatial and temporal variations. Nitrate concentration ranged from 10 to 529mg/l, with 82% of the wells above the drinking water threshold of 50mg NO3/l. Nitrate isotopic composition ranged from +5.3‰ to +35.3‰ for δ15N and from +0.4‰ to +17.6‰ for , and the samples showed a positive correlation between δ15N and , with a ɛN/ɛO ratio of 1.8, consistent with denitrification processes. The link between denitrification and pyrite oxidation is demonstrated by coupling chemical data with nitrate and sulfate isotopes. Furthermore, a spatial distribution of samples with significant denitrification was observed, allowing us to determine two main hydrogeological zones where natural attenuation was most effective. In several of the studied points, denitrification processes related to pyrite oxidation predominated and an estimation of the isotopic enrichment factors was performed using the temporal variations of nitrate concentration and the isotopic composition of dissolved nitrate ( and ). Finally, using estimated isotopic enrichment factors, an approximation of the degree of natural attenuation of nitrate was performed on those samples showing clear denitrification, and a median value of 30% of contaminant diminution was obtained. [Copyright &y& Elsevier]

Abstract: Human activities exert many pressures on the quality of groundwater, and advanced assessment programmes are needed to design sustainable water management strategies. To contribute to this challenge, the nitrate pollution problem of groundwater wells in the small scale farming systems of the Niayes region in Senegal is assessed and explained in terms of well characteristics and land use properties. A field campaign was performed in 2007 to collect basic background data of the small scale farming systems and well water was analysed in 131 wells for nitrate content, pH and electrical conductivity. For a subset of wells, soil analyses were made of the well environment for assessing the attenuation properties of the protecting soil. Cluster analysis was used to define a well typology, while principal component and multiple correspondence analyses were used to relate the nitrate pollution to well characteristics and land use properties. The study confirms that the wells are seriously affected by the nitrate pollution problem. Wells can be classified in three well classes which exhibit highest nitrate content in the southern part, while the salinity affects particularly the wells in the northern area of the region. The nitrate levels exceeding 50mg/L are more common in residential areas than in the horticultural fields. The results further show that, even if direct pollution problem of wells cannot be excluded, pollution from leaching out of the root zone of vegetable crops to the groundwater is likely. This is confirmed by the assessment of the farming activities in this area and this is consistent with the low attenuation properties of the soils characterizing this region. Considering the nitrate pollution threshold, very few non-polluting crops can be distinguished in this region, which calls for an urgent adoption of agriculture management to protect water resources from further deterioration. [Copyright &y& Elsevier]

The alluvial aquifer of the Alto Guadalquivir River is one of the most important shallow aquifers in Jaén, Spain. It is located in the central-eastern part of the province, and its groundwater resources are used mainly for crop irrigation in an agriculture-dominated area. Hydrochemical and water-quality data obtained through a 2-year sampling (2004–2006) and analysis program indicate that nitrate pollution is a serious problem affecting groundwater due to the use of nitrogen (N)-fertilizers in agriculture. During the study, 231 water samples were collected from wells and springs to determine water chemistry and the extent of nitrate pollution. The concentration of nitrate in groundwater ranged from 1.25 to 320.88 mg/l. Considerable seasonal fluctuations in groundwater quality were observed as a consequence of agricultural practices and other factors such as annual rainfall distribution and the Guadalquivir River flow regime. The chemical composition of the water is not only influenced by agricultural practices, but also by interaction with the alluvial sediments. The dissolution of evaporites accounts for part of the Na+, K+, Cl−, SO4 2−, Mg2+, and Ca2+, but other processes, such as calcite precipitation and dedolomitization, also contribute to groundwater chemistry. [ABSTRACT FROM AUTHOR]

Mediterranean Spain is a region with intensive agricultural production combined with an important seasonal water demand for water supply. High application rates of inorganic nitrogen fertiliser, input of plant protection products and intensive irrigation, sometimes with treated wastewater, is a common practice. As a result, most aquifers show nitrate contamination problems of agricultural origin. Data on pesticide residues is scarce, as systematic monitoring is not currently done. In Majorca Island, values up to 700 mg/l of nitrate in groundwater have been observed. To analyse the current situation derived from non-point pollution, several actions have been taken at different scales: declaration of a nitrate vulnerable zone, field experiments to evaluate nitrogen transport to the aquifer and the development of a GIS-simulation model to generate nitrate risk maps. [ABSTRACT FROM AUTHOR]

• Multi-isotopic and molecular source tracking data show high agreement to identify nitrate sources. • ẟ 11B in effluents of wastewater treatment plant can be affected by livestock wastes. • Information obtained was employed by local authorities to establish new vulnerable zones. Nitrate (NO 3 -) pollution adversely impacts surface and groundwater quality. In recent decades, many countries have implemented measures to control and reduce anthropogenic nitrate pollution in water resources. However, to effectively implement mitigation measures at the origin of pollution,the source of nitrate must first be identified. The stable nitrogen and oxygen isotopes of NO 3 - (ẟ 15N and ẟ 18O) have been widely used to identify NO 3 - sources in water, and their combination with other stable isotopes such as boron (ẟ 11B) has further improved nitrate source identification. However, the use of these datasets has been limited due to their overlapping isotopic ranges, mixing between sources, and/or isotopic fractionation related to physicochemical processes. To overcome these limitations, we combined a multi-isotopic analysis with fecal indicator bacteria (FIB) and microbial source tracking (MST) techniques to improve nitrate origin identification. We applied this novel approach on 149 groundwater and 39 surface water samples distributed across Catalonia (NE Spain). A further 18 wastewater treatment plant (WWTP) effluents were also isotopically and biologically characterized. The groundwater and surface water results confirm that isotopes and MST analyses were complementary and provided more reliable information on the source of nitrate contamination. The isotope and MST data agreed or partially agreed in most of the samples evaluated (79 %). This approach was especially useful for nitrate pollution tracing in surface water but was also effective in groundwater samples influenced by organic nitrate pollution. Furthermore, the findings from the WWTP effluents suggest that the use of literature values to define the isotopic ranges of anthropogenic sources can constrain interpretations. We therefore recommend that local sources be isotopically characterized for accurate interpretations. For instance, the detection of MST inferred animal influence in some WWTP effluents, but the ẟ 11B values were higher than those reported in the literature for wastewater. The results of this study have been used by local water authorities to review uncertain cases and identify new vulnerable zones in Catalonia according to the European Nitrate Directive (91/676/CEE). Image, graphical abstract [ABSTRACT FROM AUTHOR]

Agricultural practices have raised the level of nutrients reaching aquifers. In Europe, nitrate pollution is considered as one of the main threats for the quality of groundwater in agricultural areas. Treatment wetlands (TWs), also known as Constructed Wetlands, are used for groundwater treatment in areas with an important concentration of nitrogen compounds; total nitrogen removal depends on the type and operation scheme. Cork by-product from the industry has shown clear adsorbent properties to remove organic pollutants. The work is focused on the characterization of microbial communities involved in the nitrate‑nitrogen removal process in groundwater polluted from agricultural activities. The experimental design allowed the comparison of nitrate removal efficiency depending on the filter media material, cork by-product or gravel, used in two hybrid TWs (a vertical flow cell followed by a horizontal subsurface flow cell), installed in areas close to two irrigated agricultural plots at the Lleida plain area (Spain). Both physicochemical and microbial results were consistent and confirm the nitrate removal efficiency using cork as a filter media. A significant (p = 0.0025) higher removal in Bellvís TW using cork compared with the Vilanova de la Barca gravel system was observed, achieving a removal rate from 80 to 99% compared to the 5-46%, respectively. Regarding the community composition of the two different TWs, microorganisms were mainly related to the phylum Proteobacteria, and included members found to be key players in the nitrogen cycle, such as ammonia and nitrite oxidizers, as well as denitrifiers. Also, the group Bacteroidetes turns to be another abundant phylum from our bacterial dataset, whose members are suggested to be strongly involved in denitrification processes. Some groups showed to prevail depending on the type of media (cork or gravel); Firmicutes and Delta and Epsilonproteobacteria had a significant higher abundance in the TW with cork, while Acidobacteria and Planctomyces were prevalent in gravel. Therefore, cork could be an alternative material used by treatment wetlands to minimize the impact in the environment caused by nitrogen pollution in groundwater bodies., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Contamination from agricultural sources and, in particular, nitrate pollution, is one of the main concerns in groundwater management. However, this type of pollution entails the entrance of other substances into the aquifer, as well as it may promote other processes. In this study, we deal with hydrochemical and isotopic analysis of groundwater samples from four distinct zones in Catalonia (NE Spain), which include 5 different aquifer types, to investigate the influence of fertilization on the overall hydrochemical composition of groundwater. Results indicate that intense fertilizer application, causing high nitrate pollution in aquifers, also homogenize the contents of the major dissolved ions (i.e.; Cl(-), SO4(2-), Ca(2+), Na(+), K(+), and Mg(2+)). Thus, when groundwater in igneous and sedimentary aquifers is compared, significant differences are observed under natural conditions for Cl(-), Na(+) and Ca(2+) (with p-values ranging from <0.001 to 0.038), and when high nitrate concentrations occur, these differences are reduced (most p-values ranged between 0.054 and 0.978). Moreover, positive linear relationships between nitrate and some ions are found indicating the magnitude of the fertilization impact on groundwater hydrochemistry (with R(2) values of 0.490, 0.609 and 0.470, for SO4(2-), Ca(2+) and Cl(-), respectively). Nevertheless, the increasing concentration of specific ions is not only attributed to agricultural pollution, but to their enhancing effect upon the biogeochemical processes that control water-rock interactions. Such results raise awareness that these processes should be evaluated in advance in order to assess an adequate groundwater resources management., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Salinization of water bodies represents a significant risk in water systems. The salinization of waters in a small irrigated hydrological basin is studied herein through an integrated hydrogeochemical study including multivariate statistical analyses and geochemical modeling. The study zone has two well differentiated geologic materials: (i) Quaternary sediments of low salinity and high permeability and (ii) Tertiary sediments of high salinity and very low permeability. In this work, soil samples were collected and leaching experiments conducted on them in the laboratory. In addition, water samples were collected from precipitation, irrigation, groundwater, spring and surface waters. The waters show an increase in salinity from precipitation and irrigation water to ground- and, finally, surface water. The enrichment in salinity is related to the dissolution of soluble mineral present mainly in the Tertiary materials. Cation exchange, precipitation of calcite and, probably, incongruent dissolution of dolomite, have been inferred from the hydrochemical data set. Multivariate statistical analysis provided information about the structure of the data, differentiating the group of surface waters from the groundwaters and the salinization from the nitrate pollution processes. The available information was included in geochemical models in which hypothesis of consistency and thermodynamic feasibility were checked. The assessment of the collected information pointed to a natural control on salinization processes in the Lerma Basin with minimal influence of anthropogenic factors., (Copyright © 2014 Elsevier B.V. All rights reserved.)