A novel LUMNAqSoP approach for prioritising groundwater monitoring stations for implementation of the Nitrates Directive

Background: The Nitrates Directive (ND) is an EU anti-pollution legislative that, for almost 30 years, has controlled and protected hydro-resources against excessive levels of nitrates originating from agroecosystems, striving to prevent the further exacerbation of the nitrates in aquatic environments. ND sets several principal goals that member states must accomplish, such as performing spatiotemporal nitrate analyses in ground/surface water networks to achieve national water quality monitoring programme. Results: In this study, using the novel LUMNAqSoP approach, the prioritisation of 151 candidate groundwater stations for ND monitoring in Croatia was performed. The LUMNAqSoP integratively evaluates: (i) the most dominant loads from the agroecosystem (land use and management, net nitrogen application) and (ii) environmental (aquifer and soil) vulnerabilities and sensitivities of groundwater resources to nitrate pollution. By comparing stations which scored the most agro-environmental loads vs. the data from water stations containing elevated mean nitrate concentrations (from existing monitoring programmes) a very good agreement was confirmed. Moreover, deviations close to large urban zones were detected, suggesting that elevated nitrates in groundwaters in those areas likely originated from municipal/industrial rather than agricultural sources; however, further studies are needed for elucidation. Conclusions: The presented approach can serve as a useful tool to policy makers and regulators for: (i) more efficient and reliable establishment of water monitoring programme pursuant to ND, as well as (ii) better management and shaping (designating/derogating) of nitrate-vulnerable zones, especially in diverse environmental conditions and dynamic agroecosystems as have been confirmed in recent decades across the EU member states.

Automated summary

The Nitrates Directive is an EU legislation aimed at controlling nitrate pollution and protecting hydro-resources. The study in Croatia used a new approach to prioritize groundwater stations for monitoring based on agricultural loads and environmental vulnerabilities, confirming good agreement between agro-environmental loads and nitrate concentrations in water stations. The approach can be a useful tool for policy makers to establish efficient water monitoring programs and manage nitrate-vulnerable zones in diverse environmental conditions.