Origin of dissolved nitrates and mechanisms of transport to/removal from surface and groundwater (2008-ongoing)
partners: University of Pavia, ERSAF Lombardia, University of Milan, CNR-IRSA, ARPA Lombardia
supported by: Regione Lombardia and National Research Council (CNR)
Agricultural regions commonly suffer diffuse groundwater pollution by nitrates, resulting from the cumulative effect of day to day activities, including application of synthetic fertilisers, manure spreading and sewage sludge disposal. Locally, point source pollution may arise from discharges from urban or industrial N bearing wastewater and septic leachate in areas not connected to a sewage system When multiple potential nitrate sources exist, identification of the main sources and estimation of their contribution is essential to implement effective, source-oriented remediation measures. In this case, stable isotopes of dissolved nitrates (δ15N and δ18O) represent a powerful tool, complementary to existing monitoring data, enabling the identification of nitrate sources, the assessment of their relative contribution to nitrate pollution and the quantification of nitrate transport and removal processes. Additional information can be provided by B and Sr isotopes, allowing a better discrimination between manure and sewage derived nitrates.
The Po plain supports most of the agricultural and industrial activities of Northern Italy, and hosts several large urban settlements, all associated with groundwater exploitation and pollution. In Lombardy, the implementation of the Water Framework Directive (2000/60/EC) and the Nitrate Directive (91/976/EEC) has lead to the designation of large areas vulnerable to nitrate pollution, covering about half of the plain area, where the use of fertilisers, especially manure, is restricted. Nevertheless remedies taken seem not to be effective because nitrate pollution may originate from other unknown sources (e.g. domestic, greenhouses). Knowledge of the source of nitrate pollution would therefore enable the application of local, source oriented remedies.
The project is organised in three objectives investigating nitrate origin and attenuation processes using isotope techniques in different settings:
Publications:
Sacchi E., Pilla G., gerbert-gaillard l., Zuppi G.M. (2007) - A regional survey on nitrate contamination of the Po valley alluvial aquifer (Northern Italy). Int. Symp. on Advances in Isotope Hydrology and its role in Sustainable Water Resources Management, IAEA, Vienna 21-25 May 2007, IAEA-CN-151/34, vol., 2, 471-478
Sacchi E., Pilla G., GUFFANTI S., ALLAIS E., DELCONTE C. (2009) Stable isotopes of dissolved nitrate as indicators of the origin and mechanisms of transport to/removal from groundwater: results from the western Po plain. The 16th Nitrogen Workshop, Turin (Italy) 28/06/09 - 01/07/09, 495-496.
supported by: Regione Lombardia and National Research Council (CNR)
Agricultural regions commonly suffer diffuse groundwater pollution by nitrates, resulting from the cumulative effect of day to day activities, including application of synthetic fertilisers, manure spreading and sewage sludge disposal. Locally, point source pollution may arise from discharges from urban or industrial N bearing wastewater and septic leachate in areas not connected to a sewage system When multiple potential nitrate sources exist, identification of the main sources and estimation of their contribution is essential to implement effective, source-oriented remediation measures. In this case, stable isotopes of dissolved nitrates (δ15N and δ18O) represent a powerful tool, complementary to existing monitoring data, enabling the identification of nitrate sources, the assessment of their relative contribution to nitrate pollution and the quantification of nitrate transport and removal processes. Additional information can be provided by B and Sr isotopes, allowing a better discrimination between manure and sewage derived nitrates.
The Po plain supports most of the agricultural and industrial activities of Northern Italy, and hosts several large urban settlements, all associated with groundwater exploitation and pollution. In Lombardy, the implementation of the Water Framework Directive (2000/60/EC) and the Nitrate Directive (91/976/EEC) has lead to the designation of large areas vulnerable to nitrate pollution, covering about half of the plain area, where the use of fertilisers, especially manure, is restricted. Nevertheless remedies taken seem not to be effective because nitrate pollution may originate from other unknown sources (e.g. domestic, greenhouses). Knowledge of the source of nitrate pollution would therefore enable the application of local, source oriented remedies.
The project is organised in three objectives investigating nitrate origin and attenuation processes using isotope techniques in different settings:
- the characterisation of the input signal (fertilisers, manure, septic leachate) and the transformations occurring within the unsaturated zone. The investigation is conducted in close collaboration with ERSAF Lombardia and the University of Milan, in experimental fields equipped with water samplers at different depth;
- surface water (main rivers and irrigation channels). The investigation is conducted in collaboration with the Regional Environmental Agency (ARPA Lombardia) conducting the water quality monitoring programme, and CNR-IRSA, investigating denitrification processes occurring in river banks;
- groundwater resources. This part of the project is also developed in collaboration with ARPA Lombardia and the University of Milano Bicocca.
Publications:
Sacchi E., Pilla G., gerbert-gaillard l., Zuppi G.M. (2007) - A regional survey on nitrate contamination of the Po valley alluvial aquifer (Northern Italy). Int. Symp. on Advances in Isotope Hydrology and its role in Sustainable Water Resources Management, IAEA, Vienna 21-25 May 2007, IAEA-CN-151/34, vol., 2, 471-478
Sacchi E., Pilla G., GUFFANTI S., ALLAIS E., DELCONTE C. (2009) Stable isotopes of dissolved nitrate as indicators of the origin and mechanisms of transport to/removal from groundwater: results from the western Po plain. The 16th Nitrogen Workshop, Turin (Italy) 28/06/09 - 01/07/09, 495-496.
Other case studies
Tracing nitrification and denitrification in a periodically flooded shallow sandy aquifer
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Origin and effects of nitrogen pollution in groundwater traced by δ15N-NO3 and δ18O-NO3: the case of Abidjan (Ivory Coast)
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