Nitrate Vulnerable Zones Research Articles

Protection from natural and anthropogenic sources: a new rating methodology to delineate “Nitrate Vulnerable Zones”

In the last years, because of uncontrolled human activities, a significant increase of groundwater pollution occurred worldwide, with nitrate being among the most widespread pollutants. The assessment of groundwater vulnerability represents an important tool for developing groundwater quality plans and in the delimitation of “Nitrate Vulnerable Zones”. In this study, three rating methods (DRASTIC, SINTACS and GOD) were applied in an alluvial plain to check the reliability of the results comparing the obtained thematic maps with the observed nitrate concentrations in groundwater. Results show that without large modifications for specific vulnerability, these methodologies cannot describe the actual groundwater nitrate distribution in the study area. A new easy methodology called Protection from Natural and Anthropogenic sources (PNA) was then defined and tested. The PNA map divides the study area in five classes of vulnerability from very low to very high and shows a fair correlation with groundwater nitrate concentrations. The selection of the parameters and of the algorithm makes PNA strongly flexible and applicable in similar watersheds around the world, as a tool for the delineation of “Nitrate Vulnerable Zones”.

Dried Pig Manure from a Cogeneration Plant as a Fertilizer for Nitrate Vulnerable Zones

Nitrate vulnerable zones (NVZs) are areas considered to be at high risk of water pollution due to an excess of nitrates and, according to European regulations, codes of good agricultural practice are to be implemented by farmers, such as reducing doses of the applied fertilizers, or the use of fertilizers that minimize nitrate leaching. In this work, the influence of organic fertilization with dried pig manure (DPM) as compared to mineral fertilization with ammonium sulfate nitrate with 3,4-dimethylpyrazole phosphate nitrification inhibitor was studied in a barley crop planted in a NVZ in Fompedraza (Valladolid, Spain). Organic and mineral fertilizers were applied at different rates (85, 133 and 170 kg N·ha−1·year−1 vs. 90 and 108 kg N·ha−1·year−1, respectively) over a three-year period, in a randomized complete block design with six treatments and four blocks. DPM-based fertilization resulted in a 65% increase in crop yield as compared to the control soil, reaching 1800 kg·ha−1 for an application rate of 85 kg N·ha−1·year−1. Higher DPM rates were found to increase the electrical conductivity and assimilable phosphorus, potassium, magnesium and organic matter contents, but did not lead to yield enhancements. Final nitrate and ammonium concentrations were lower than 10 mg·kg−1 and 20 mg·kg−1, respectively, and no increase in soil salinity or heavy metal pollution was observed. DPM fertilization should be supplemented with small doses of inorganic fertilizers to obtain crop yields similar to those attained with mineral fertilization.

EU Regulations to Fight Nutrient Surpluses: the Case of Nitrate Vulnerable Zones

EU Regulations to Fight Nutrient Surpluses: the Case of Nitrate Vulnerable Zones

Groundwater quality and vulnerability assessment in west Luxor Governorate, Egypt

Groundwater is the main source of water for different purposes in the desert areas of Egypt. The agricultural and different human activities in line with hydrological characteristics have influenced the quality of this water resource. The main aim of this work was the determination of groundwater quality and vulnerability to pollution in west Luxor Governorate, Egypt. For completion of this work, 50 boreholes were sampled during October 2014 and groundwater samples were analyzed chemically. Hydrological, topographic, lithological, climatic conditions and land use data, which considered key factors for pollutants transport, were also collected for building groundwater vulnerability maps. The results revealed high levels of groundwater pollution with NO3¯, Cd and Pb, as well as increased levels of total dissolved solids. The map of intrinsic groundwater vulnerability (based on the IV index; Arauzo 2017) showed medium and high levels of vulnerability associated with natural factors in 62% and 38% of the area, respectively. The map of specific groundwater vulnerability (based on the LU-IV procedure; Arauzo 2017) indicated that 52% of the area showed high to extreme levels of vulnerability to nitrate pollution from nonpoint sources. From this, it was concluded that the study area can be considered as Nitrate Vulnerable Zone (NVZ) and, therefore, specific measures (including optimization of water and N-fertilizers applications) must be taken in order to restore water quality.

AkvaGIS: An open source tool for water quantity and quality management

AkvaGIS is a novel, free and open source module included in the FREEWAT plugin for QGIS that supplies a standardized and easy-to-use workflow for the storage, management, visualization and analysis of hydrochemical and hydrogeological data. The main application is devised to simplify the characterization of groundwater bodies for the purpose of building rigorous and data-based environmental conceptual models (as required in Europe by the Water Framework Directive). For data-based groundwater management, AkvaGIS can be used to prepare input files for most groundwater flow numerical models in all of the available formats in QGIS. AkvaGIS is applied in the Walloon Region (Belgium) to demonstrate its functionalities. The results support a better understanding of the hydrochemical relationship among aquifers in the region and can be used as a baseline for the development of new analyses, e.g., further delineation of nitrate vulnerable zones and management of the monitoring network to control chemical spatial and temporal evolution. AkvaGIS can be expanded and adapted for further environmental applications as the FREEWAT community grows.

Managing runoff and soil loss in asparagus production systems

On slightly sloping land, current asparagus cultivation practices (including prolonged periods of bare soil, surface capping and compaction of wheelings) can lead to runoff and soil loss. This can result in on-site impacts to crops and field operations and offsite impacts on the wider environment. Research into soil and water management in green asparagus production has been undertaken in the UK since 2010. This paper details two separate runoff and erosion trials conducted in 2012 and 2013 on commercial asparagus fields. Each trial has tested the efficacy of a range of treatments applied to inter-row wheelings including green waste compost (of PAS:100 quality protocol standard) and wheat straw mulch at different application rates, both with and without shallow soil disturbance. It was realised early on that compost was ineffective in runoff and soil loss management where application quantity was restricted by nitrogen regulations in Nitrate Vulnerable Zones. Straw mulch alone has consistently reduced soil loss across both trials by 72 to 87% as compared to the bare soil control. Shallow soil disturbance alone reduced soil loss by 4 to 13%, with no significant differences observed between various tillage implements tested. Despite the reductions observed in soil loss, runoff sediment concentration still exceeds that stipulated by EU Directive for surface water quality; risking pollution of any receiving water bodies. The knowledge gained from these studies should be used to develop more effective runoff and soil loss control in order to ensure the future sustainability of asparagus production.

Evaluation of estuarine biotic indices to assess macro-benthic structure and functioning following nutrient remediation actions: A case study on the Eden estuary Scotland

Despite a wealth of methods currently proposed by the European Water Framework Directive (WFD) to assess macro-benthic integrity, determining good ecological status (GES) and assessing ecosystem recovery following anthropogenic degradation is still one of the biggest challenges in marine ecology research. In this study, our aim was to test a number of commonly used structural (e.g. Shannon–Wiener, Average Taxonomic Diversity (Δ), M-AMBI) and functional indicators (e.g. BTA, BPc) currently used in benthic research and monitoring programmes on the Eden estuary (Scotland). Historically the estuary has a legacy of high nutrient conditions and was designated as a Nitrate Vulnerable Zone (NVZ) in 2003, whence major management measures were implemented in order to ameliorate the risk of eutrophication symptoms. We therefore collected data on intertidal macro-benthic communities over a sixteen year interval, covering a pre-management (1999) and post-management (2015) period to assess the effectiveness of the intended restoration efforts. In the post-management period, the results suggested an improvement in the structure and functioning of the estuary as a whole, but macro-benthic assemblages responded to restoration variably along the estuarine gradient. The greatest improvements were noticed in the upper and central sites of the estuary with functional traits analysis suggesting an increased ability of these sites to provide ecosystem services associated with the benthic environment such as carbon and organic matter cycling. Generally, almost all of the structural and functional indicators detected the prevailing environmental conditions (with the exception of (Pielou’s index and Average Taxonomic Diversity (Δ)), highlighting the appropriateness of such methods to be used in monitoring the recovery of transitional systems. This research also provides a robust baseline to monitor further management actions in the Eden estuary and provides evidence that notable reductions in nitrate concentrations resulting from NVZ designations may result in significant improvements to benthic structure and functioning.

Nitrate Vulnerable Zones Revision in Poland—Assessment of Environmental Impact and Land Use Conflicts

Despite concerted efforts through the European territory, the problems of nitrogen pollution released from agricultural sources have not been resolved yet. Therefore, infringement cases are still open against a few Member States, including Poland, based on fulfilment problems of commitments regarding the Nitrate Directive. As a result of the litigation process, Poland has completely changed its approach to nitrate vulnerable zones. Instead of just selected areas, the measured actions will be implemented throughout the whole Polish territory. Additionally, further restrictions concerning the fertilizer use calendar will be introduced in areas indicated as extremely cold or hot, based on the average temperature distribution (poles of cold, and heat). Such a change will be of key importance to farmers, whose protests are already audible throughout the country, and can be expected to intensify. To assess the impact of the introduced modifications a modelling approach has been adopted. The use of the Macromodel DNS/SWAT allowed for the development of baseline and variant scenarios incorporating details of stipulated changes in the fertilizer use for a pilot catchment (Słupia River). The results clearly indicate that the new restriction will have a substantial effect on the aquatic environment by altering the amount of released total nitrogen.

Source and fate of nitrate in contaminated groundwater systems: Assessing spatial and temporal variations by hydrogeochemistry and multiple stable isotope tools

Intensive farming usually imply a degradation of groundwater resources worldwide. In particular, nitrate concentrations exceeding the 50 mg L−1 limit established for drinking water pose the human health at risk. Therefore, assessing the impact of farming on groundwater, in terms of space and time, is of fundamental importance for policy decision makers and land managers. This study was aimed at assessing the nitrate source and fate in groundwater by combining hydrogeochemical and isotopic tools. The study area is located in the coastal plain of Arborea (Italy), a nitrate vulnerable zone (NVZ) due to intensive farming and animal husbandry (28,000 bovine livestock units). This area represents Mediterranean environments where groundwater resources are of relevant importance.In order to assess the present level of groundwater contamination and evaluate temporal variations, 6 hydrogeochemical surveys were carried out bimonthly at 13 sampling sites located in an area of 6 km2. Additional samples were collected in specific surveys (82 water samples in total). The physical-chemical parameters, nitrogen species concentrations, major and minor components were determined, together with the boron, hydrogen, oxygen, nitrogen, and sulfur isotopic delta values.Results showed that groundwater samples were of meteoric origin, as indicated by the δ2H and δ18OH2O values. The groundwater showed near-neutral pH (6.8–7.9) and different values of redox potential (0.2 ÷ 0.5 V), dissolved oxygen (2 ÷ 6 mg L−1), electrical conductivity (0.8 ÷ 2.1 mS cm−1) and chemical composition (sodium-chloride ÷ calcium-bicarbonate). Nitrate was not homogeneously distributed in groundwater, being observed a large range of concentrations, from <1 up to 162 mg L−1. The above differences reflected the variability of groundwater circulation at small scale, which in turn controlled the interaction of water with different sediments (sands and/or clays). The shallow wells (about 5 m depth), screened in groundwater interacting mainly with sands, showed marked variations under the monitoring period, with nitrate peaks reflecting high leaching of nitrate in correspondence of fertilization and irrigation periods. The deeper wells (15–37 m depth) showed high to moderate nitrate when screened in sandy aquifer, whereas they had very low nitrate and relatively high ammonium (up to 1.8 mg L−1) when clay layers were intercepted.Trends of δ15N and δ18ONO3 values in the nitrate of shallow groundwater were related to the nitrate concentration observed over the monitored period. This dual isotope systematic showed a likely source of nitrate in groundwater from either manure or sewage. The δ11B signature coupled to δ15N values clearly identified the manure as the predominant source of nitrate in the shallow and deep groundwater at Arborea. Relative enrichments in heavy nitrogen coupled to high concentrations of nitrate in groundwater were mainly attributed to volatilization processes occurring during the storage of animal wastes prior to application on the soil. Mixing of groundwater with seawater was not recognized, whereas mixing between shallow and deep groundwater may have occurred locally.Natural attenuation of nitrate contamination was observed in the deep groundwater interacting with lagoon clays rich in organic matter. Heterotrophic denitrification processes were highlighted by relatively high δ15N, δ18ONO3, δ34S and δ18OSO4 values in association with low SO42−/Cl− and high HCO3−/SO42− molar ratios observed in the groundwater with low concentration of nitrate.Results of this study showed that site-specific investigations are required for designing the best practices aimed at preserving groundwater resources under Mediterranean conditions. The spreading of animal waste on soils affects groundwater systems and likely extends over long time, strongly depending on the time lag of nutrient transport from source areas to receptor wells. Therefore, adequate monitoring of groundwater quality is required in areas of intensive farming.

Application of nitrogen and boron isotopes for tracing sources of anthropogenic contamination in Monforte-Alter do Chão aquifer system, Portugal

The Monforte-Alter do Chao aquifer system represents one of the main water resources in Alentejo region (SW Portugal), and is located in an area of intensive agriculture and cattle breeding. The groundwater shows varied chemical composition, reflecting fast chemical changes associated with the water–rock interaction, with waters of Ca–HCO3, Na/Ca–HCO3, and Na–HCO3 facies. Some of the waters have strong evidence of nitrogen contamination with nitrate concentrations above 50 mg/l. The implementation of the European Nitrates Directive and the Water Framework Directive has led to the designation of large areas as Nitrate Vulnerable Zones, for being at risk from agricultural nitrate pollution: groundwater containing or that could contain more than 50 mg/l of nitrates. Corrective measures taken to reverse the trend can only be established when the contaminant source is known. In this study, the isotopic compositions of NO3 (δ15N and δ18O) and B (δ11B) were used to identify the sources of the nitrogen contamination. Despite the occurrence of some evaporation processes, the δ15N and δ18O isotopes allowed to distinguish two groups of waters with different sources of nitrates, fertilizers, and soils or manure and domestic effluents. The analysis of the NO3 source based on δ11B isotope ratio pointed out contamination by pig farms effluents. However, considering the land occupation and the strong livestock activities in the area, it is possible that the adsorption of 11B isotopes onto clays or the high pH of the groundwater could explain the high δ11B values.

Potential yield of wheat in the United Kingdom: How to reach 20 t ha−1

Given the need for increased yields in wheat, new cultivars will be wanted with higher potential yield (in optimal physical environment, without weeds, pests or diseases). The aim in the United Kingdom is 20 t ha−1.Potential yield can be predicted from the annual total solar radiation incident on the crop, the fraction of incident photosynthetically active radiation (PAR) which is intercepted, radiation use efficiency (RUE), and harvest index. The potential yield of current crops (interception of 0.46 of annual incident PAR; RUE 2.7 g MJ−1 dry matter above ground, intercepted PAR; harvest index 0.5) was 12–14 t ha−1 for annual solar radiation 3300–3800 MJ m−2 which is typical across wheat-growing regions of the United Kingdom. Many combinations of increases in interception (especially retention of green leaves into August and September), RUE and harvest index would achieve potential yields of 20 t ha−1 in sunny locations or sunny years with annual solar radiation of 3800 MJ m−2 or above.Advancing growth duration by one month reduced yields because there was little radiation to be intercepted in March and much to be missed in July and August. If duration was advanced one month and extended by one month of maximum interception then yields were increased by around 16%.From the relationships among yield, nitrogen concentrations of grain and straw, and nitrogen supply from soil and fertilizer, yields of 20 t ha−1 would require fertilizer application of 450–680 kg N ha−1 for breadmaking wheat (13% protein) and 350–580 kg N ha−1 for feed wheat (11% protein), with soil supply 100–200 kg N ha−1 and harvest index 0.5–0.6. If nitrogen application was restricted to the N-max limit for Nitrate Vulnerable Zones (440–500 kg N ha−1) then 20 t ha−1 was achievable only with soil supply well above 100 kg N ha−1.Potential yield of wheat of 20 t ha−1 is possible in the United Kingdom from new cultivars with improved interception of radiation, RUE and harvest index (e.g. by 17%, 32% and 18%, respectively). Improved RUE can be exploited if optimum water and nutrients are maintained throughout crop duration. Increased harvest index raises yield and reduces straw and also produces a larger yield for a given amount of nitrogen supplied. High-yielding crops will require proportionate increases in nitrogen supply from the soil and fertilizer.

A Simplified Nitrogen Assessment in Tagus River Basin: A Management Focused Review

Interactions among nitrogen (N) management and water resources quality are complex and enhanced in transboundary river basins. This is the case of Tagus River, which is an important river flowing from Spain to Portugal in the Iberian Peninsula. The aim was to provide a N assessment review along the Tagus River Basin regarding mostly agriculture, livestock, and urban activities. To estimate reactive nitrogen (Nr) load into surface waters, emission factor approaches were applied. Nr pressures are much higher in Spain than in Portugal (~13 times), which is mostly because of livestock intensification. Some policy and technical measures have been defined aiming at solving this problem. Main policy responses were the designation of Nitrate Vulnerable and Sensitive Zones, according to European Union (EU) directives. Nitrate Vulnerable Zone comprise approximately one third of both territories. On the contrary, Sensitive Zones are more extended in Spain, attaining 60% of the watershed, against only 30% in Portugal. Technical measures comprised advanced urban and industrial wastewater treatment that was designed to remove N compounds before discharge in the water bodies. Given this assessment, Tagus River Basin sustainability can only be guaranteed through load inputs reductions and effective transnational management processes of water flows.

Hydrogeological and multi-isotopic approach to define nitrate pollution and denitrification processes in a coastal aquifer (Sardinia, Italy)

Agricultural coastal areas are frequently affected by the superimposition of various processes, with a combination of anthropogenic and natural sources, which degrade groundwater quality. In the coastal multi-aquifer system of Arborea (Italy)—a reclaimed morass area identified as a nitrate vulnerable zone, according to Nitrate Directive 91/676/EEC—intensive agricultural and livestock activities contribute to substantial nitrate contamination. For this reason, the area can be considered a bench test for tuning an appropriate methodology aiming to trace the nitrate contamination in different conditions. An approach combining environmental isotopes, water quality and hydrogeological indicators was therefore used to understand the origins and attenuation mechanisms of nitrate pollution and to define the relationship between contaminant and groundwater flow dynamics through the multi-aquifer characterized by sandy (SHU), alluvial (AHU), and volcanic hydrogeological (VHU) units. Various groundwater chemical pathways were consistent with both different nitrogen sources and groundwater dynamics. Isotope composition suggests a mixed source for nitrate (organic and synthetic fertilizer), especially for the AHU and SHU groundwater. Moreover, marked heterotrophic denitrification and sulfate reduction processes were detected; although, for the contamination related to synthetic fertilizer, the attenuation was inefficient at removing NO3− to less than the human consumption threshold of 50 mg/L. Various factors contributed to control the distribution of the redox processes, such as the availability of carbon sources (organic fertilizer and the presence of lagoon-deposited aquitards), well depth, and groundwater flow paths. The characterization of these processes supports water-resource management plans, future actions, and regulations, particularly in nitrate vulnerable zones.

An innovative method to assess suitability of Nitrate Directive measures for farm management

Controlling groundwater diffuse pollution induced by agricultural practices remains a significant challenge and has been receiving strong attention in the European Union (EU) for the last 25 years. The EU’s Nitrates Directive (91/676EC) and its associated Nitrate Vulnerable Zone (NVZ) legislation were recently revised in France in 2015, requiring farmers to adopt measures and then modify their agricultural practices to protect water resources. Yet these measures are not always implemented in an optimal way, thus limiting improvement of groundwater quality. Based on semi-directive interviews with 14 French farmers, we developed an innovative farm-scale method composed of four steps. First, we described how these farmers implemented Nitrate Directive measures. Second, we evaluated their impact on farm structure and third their consistency with farmer’s strategy. Fourth, we assessed their suitability for farm management as an integrative analysis of the previous step. Through this approach, we identified 3 types of farm management. A group of “Beyond Regulation” composed of farmers for whom Nitrate Directive measures are suitable for their farm management. They optimally implement these measures to reduce pressure on groundwater quality. For the second group named “Soft Regulation-constraints”, Nitrate Directive measures are less suitable for their farm management because they have another lucrative activity than cash crop production. This group could benefit from a redesign of the measures, changing from means- to result-oriented obligation in order to take into account the local conditions and also their farm management constraints. For the third group, denoted as “Strong Regulation-constraints”, ND measures are not suitable for their farm management. The way they implement measures is usually not optimal to reduce pressure on groundwater quality. We suggest that, investing in an “action-learning” program for such farmers could make them understand the usefulness of this regulation and help them to make the measure implementation suitable for their farm management. This farm-scale method could be used further for water management stakeholders to (i) evaluate the suitability of measures from Water Policy for the diversity of farm management or (ii) design suitable measures for the diversity of farm management on a territory subjected to groundwater pollution issue.

Life cycle assessment of biological pig manure treatment versus direct land application − a trade-off story

Excess manure can have two common fates: to be exported and applied to agricultural land, or to be treated, possibly with resource recovery (i.e. energy and/or nutrients). In this study, the environmental performance of a treatment system of pig manure (centrifugation and subsequent biological nitrogen removal from the liquid fraction and composting of the solid fraction) has been assessed using life cycle assessment (LCA) with the ReCiPe method to assess environmental impacts at midpoint and endpoint level. Such treatment system is typical for Flanders (Belgium), a region characterized by a manure excess.The performance of this treatment-scenario has been compared to the direct field application of untreated manure (no-treatment-scenario) to gain insight in the environmental trade-offs between them. The hotspots dominating the environmental impact for manure treatment were the field application of compost and the effluent from the biological treatment, and the electricity needed to run the treatment facility. The substitution of synthetic fertilizers played an important role in both scenarios (mitigation of potential damaging impacts). The comparison between the two manure management scenarios showed that the treatment scenario scores better in some categories and vice versa. Manure treatment does prevent marine eutrophication and must be carried out in nitrate-vulnerable zones, such as the studied region of Flanders. Finally, the use of single score through normalization and weighting of midpoint impacts was evaluated. This underscores a policy direction towards manure treatment, but this message should be interpreted with care as the approach of normalization and aggregation can be questioned.

Field-scale electrical resistivity profiling mapping for delineating soil condition in a nitrate vulnerable zone

Venice Lagoon is an extremely heterogeneous environment conditioned by natural changes and anthropogenic pressures. The area is a particularly vulnerable system characterized by high spatial geomorphological variability. Site-specific crop management, defined as the best strategies to manage heterogeneous farmlands, has the potential to maximize agricultural production while preserving soil and water resources. This work was aimed at identifying and characterizing spatial variability within the fields in terms of soil fertility and productive potential using precision agriculture principles. Automatic resistivity profiling (ARP) was implemented to study spatial variability of the field and to define the best localization of twenty soil sampling points. Three years’ historical yield maps were used to determine homogeneous zones within the study area. The application of a fuzzy c-means clustering algorithm led to classification of four homogeneous zones, which were assigned with productive potentials using an ANOVA test of soil features and historical yield data. Such classification was validated by a comparison of the homogeneous zone's productive potential with five-year average production.

Re-Staging La Rasgioni: Lessons Learned from Transforming a Traditional Form of Conflict Resolution to Engage Stakeholders in Agricultural Water Governance

This paper presents an informal process inspired by a public practice of conflict mediation used until a few decades ago in Gallura (NE Sardinia, Italy), named La Rasgioni (The Reason). The aim is twofold: (i) to introduce an innovative method that translates the complexity of water-related conflicts into a “dialogical tool”, aimed at enhancing social learning by adopting theatrical techniques; and (ii) to report the outcomes that emerged from the application of this method in Arborea, the main dairy cattle district and the only nitrate-vulnerable zone in Sardinia, to mediate contrasting positions between local entrepreneurs and representatives of the relevant institutions. We discuss our results in the light of four pillars, adopted as research lenses in the International research Project CADWAGO (Climate Change Adaptation and Water Governance), which consider the specific “social–ecological” components of the Arborea system, climate change adaptability in water governance institutions and organizations, systemic governance (relational) practices, and governance learning. The combination of the four CADWAGO pillars and La Rasgioni created an innovative dialogical space that enabled stakeholders and researchers to collectively identify barriers and opportunities for effective governance practices. Potential wider implications and applications of La Rasgioni process are also discussed in the paper.

Agricultural activities effects on groundwater contamination in a Nitrate Vulnerable Zone of Latina Province

This preliminary study summarizes the results of a nitrate leaching monitoring in two farms located in the Nitrate Vulnerable Zone (NVZ) of the coastal sandy aquifer of Pianura Pontina, Sabaudia (LT).The monitoring was performed by continuous measurement of piezometric levels of the groundwater aquifer and water sampling in selected wells of the area. The considered farms are representative of the two widespread cropping systems of the area: fodder crops in open field and vegetable crops in greenhouses. The experimental data were used to calibrate models and estimation procedures of leaching towards the aquifer - both the flow rate and nitrate transport and diffusion into the aquifer were evaluated. The developed procedures, under a continuous improvement, can be used to evaluate the whole coastal aquifer and to plan suitable protection measures.

Methodological approach to assessment of groundwater contamination risk in an agricultural area

Water contamination by nitrates of agricultural origin is a major problem in Sardinia (Italy) where Nitrate Vulnerable Zones (NVZs) has been identified in the Arborea reclamation area (W. Sardinia), where intensive agriculture and farming are the mainstays of the local economy. Agricultural practices have seen an increase in the use of animal and chemical fertilizers for enhancing soil productivity. This, accompanied by the intensive use of groundwater resources for irrigation has led to the deterioration of groundwater quality, in areas particularly vulnerable to nitrate contamination. In the test area, the intrinsic nitrate contamination risk from agricultural sources has been evaluated through the combined application of the parametric methods, SINTACS, SI and IPNOA. Risk assessment, using vulnerability and hazard mapping, is considered a fundamental aspect of sustainable groundwater management. All parameters used in this risk assessment were prepared, classified, weighted and integrated in a GIS environment. Results show that nitrate concentrations are located in those areas where agricultural and livestock farming are concentrated. These results could, consequently, be interesting for future development and long term planning of groundwater protection management. The risk methods adopted, verified by comparing the distribution of nitrates in the groundwater with the different vulnerability classes, proved to be a valid tool. In fact the areas with nitrate concentration of more than 100mg/l coincide well with those at high risk identified by the model and the areas with nitrate concentration of less than 25mg/l closely match those areas with low and moderate risk.

Projected impacts of increased uptake of source control mitigation measures on agricultural diffuse pollution emissions to water and air

A multi-pollutant modelling framework for England and Wales is described. This includes emissions of nitrate, phosphorus and sediment to water and ammonia, methane and nitrous oxide to air, and has been used to characterise baseline (no uptake of on-farm measures) and business-as-usual (BAU) annual pollutant losses, comparing these with the loss under a range of new policies aimed at increasing the uptake of relevant source control measures to 95% across England and Wales. Model outputs, including uncertainty ranges, evaluated using national water and air quality data layers have been summarised at both farm (Robust Farm Type) and water management catchment (WMC) scale. Nationally, across all farm types, the median annual reductions in pollutant losses under the new scenario, relative to BAU in 2010, were predicted to range between 9 and 16% for nitrate, 13–37% for phosphorus, 12–21% for sediment, 2–57% for methane and 10–17% for nitrous oxide. For ammonia, the range was −2–28%, indicating the potential for pollution swapping and an increase in ammonia emissions under scenarios designed to reduce nitrogen flux to waters. Increased uptake of pollution source control measures would result in a wide range of annual total (capital and operational) costs (per farm) for the major farm types, with median estimates ranging from £635 yr−1 (Less Favourable Areas (LFA) with grazing livestock) to £15,492 yr−1 (Cereals) in Nitrate Vulnerable Zone (NVZ) areas, compared with a range of £23 yr−1 to £13,484 yr−1 for the same respective farm types in non-NVZ areas. The estimated median annual load reductions for all WMCs relative to BAU, were predicted to be 16% for nitrate, 20% for phosphorus, 16% for sediment, 16% for ammonia, 15% for methane and 18% for nitrous oxide. These predictions suggest that almost perfect (95% uptake) implementation of source control measures will not deliver substantial improvements in pollutant emissions.