Translating the agricultural N surplus hazard into groundwater pollution risk: Implications for effectiveness of mitigation measures in nitrate vulnerable zones

Abstract

In the Nitrate Vulnerable Zones farmers are required to implement measures to reduce the nitrogen (N) surplus. Nevertheless, in some cases the status of the water bodies show that the effect of these measures remains insufficient despite the global decrease in N surpluses. The present work aims to contribute with a method that produces an appropriate indicator for the N mitigation measures effectiveness for reducing groundwater nitrate pollution. The Global Risk Index (GRI) results from overlaying the agricultural N surplus hazard and aquifer vulnerability. It includes both irrigation activity and precipitation contribution to water recharge calculated at the municipality level. It integrates a range of regional datasets combined with monitored nitrate (NO 3 − ) concentrations in groundwater under a GIS framework. Results show that the pollution status of the Tagus Vulnerable Zone (TVZ) aquifers has been aggravating in spite of the overall reduction in the N surpluses that resulted from the implementation of the Nitrates Directive measures. Twelve years after the TVZ designation, the GRI indicates high and moderate NO 3 -pollution risk, respectively in 33 % and 66 % of the territory. Scenario analysis indicates the potential of targeted measures for ending high risk areas and reducing moderate risk areas to 13 %. This supports that N mitigation measures must be reformulated and spatially targeted according to site specific hazards and vulnerabilities.

Development of a groundwater contamination index based on the agricultural hazard and aquifer vulnerability: Application to Portugal

“…The Tagus-Sado basin is the most important aquifer in the Iberian Peninsula and the main source of water for societal and agricultural purposes (Almeida et al, 2000). It is a multi-layered aquifer system, covering 8000 km 2 in a sedimentary basin where intensive agriculture occurs with implications in groundwater pollution (Cameira et al, 2019(Cameira et al, , 2021.…”

“…However, these models focus on groundwater vulnerability assessment rather than on the contamination hazard and groundwater contamination risk. Thus, they can indicate high vulnerability, but no pollution risk given the absence of a contamination load (Cameira et al, 2021). By integrating the hazard and vulnerability concepts, the present paper aims to present a more holistic approach to assess and to rate the groundwater N contamination risk at a national scale.…”

An Integrated Modeling System for the Evaluation of Water Resources in Coastal Agricultural Watersheds: Application in Almyros Basin, Thessaly, Greece

“…Complex problems of the quantity and quality of water resources of coastal agricultural watersheds, and especially of the groundwater regarding the water table depletion, the nitrate contamination, and the seawater intrusion, are encountered in the semi-arid Mediterranean coastal region [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]23,28,29,32,39]. The developed integrated modeling system consisting of coupled and interrelated models of surface and groundwater hydrology, crop growth/nitrate leaching, and groundwater contaminant transport and its application in the Almyros basin, emphasize the significance of the integrated modeling for the study and the effective and accurate analysis of the spatiotemporal patterns of groundwater flow, nitrate pollution originated by fertilizer practices, and seawater intrusion [32].…”

“…Groundwater pollution has an important role among water resources management strategies due to the majority of the semi-arid regions it is encountered. Some known examples of coastal water systems where intensive agricultural practices, for irrigation and fertilization purposes, have caused serious degradation of the groundwater resources and documented in the international literature, including Italy (Nurra region of Sardinia [3] and central-southern Italy [4]), south-eastern France (Lower Var Valley) [5], Spain (e.g., Mancha Oriental System in Jucar River Basin, Oropesa Plain, Vinaroz Plain) [6,7], Portugal (Tagus catchment) [8], Egypt (e.g., Bagoush plain, North Sinai area, East Nile Delta aquifer), Tunisia (Jerba Island), Algeria (Nador plain), Morocco (Bou-Areg aquifer) [9], Lebanon (Akkar and Damour aquifers), Syria (e.g., Latakia and Tartous groundwaters), Palestine (Gaza aquifer), Jordan (northern Jordan, Yarmouk Basin) [10], Cyprus (Magosa aquifer) [11], Turkey (e.g., Silifke-Goksu Deltai, Serik, and Tarsus Plains) [12], and in the Greek coastal areas.…”

Contrasting Considerations among Agricultural Stakeholders in Japan on Sustainable Nitrogen Management

“…However, the groundwater nitrate pollution tends to be persistent as shown in that exceedance of the nitrate standard was 17.3% in the survey of the areas adjacent to polluted wells and 42.6% in the monitoring survey of polluted wells in 2018 [40]. A general improvement in water quality regarding nitrate concentrations is usually accompanied by the existence of contamination/pollution hotspots due to agricultural activities, as demonstrated by [42,43]. This means that a closer look must be given to local and regional aspects of N losses, and all actors must be involved in the development of sustainable N management.…”