Reactive Silica Traces Manure Spreading in Alluvial Aquifers Affected by Nitrate Contamination: A Case Study in a High Plain of Northern Italy
In the northern sector of the Po River Plain (Italy), widespread intensive agriculture and animal farming are supported by large amounts of water from Alpine lakes and their emissaries. Flood irrigation and excess fertilization with manure affect both the hydrology and the chemical quality of surfac...
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doaj-8e70ed250af440b59e2cdf60608214c82020-11-25T03:31:47ZengMDPI AGWater2073-44412020-09-01122511251110.3390/w12092511Reactive Silica Traces Manure Spreading in Alluvial Aquifers Affected by Nitrate Contamination: A Case Study in a High Plain of Northern ItalyEdoardo Severini0Marco Bartoli1Monica Pinardi2Fulvio Celico3Department of Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area Delle Scienze 11/A, 43124 Parma, ItalyDepartment of Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area Delle Scienze 11/A, 43124 Parma, ItalyInstitute for Electromagnetic Sensing of the Environment, National Research Council of Italy (CNR-IREA), 20133 Milan, ItalyDepartment of Chemistry, Life Science and Environmental Sustainability, University of Parma, Parco Area Delle Scienze 11/A, 43124 Parma, ItalyIn the northern sector of the Po River Plain (Italy), widespread intensive agriculture and animal farming are supported by large amounts of water from Alpine lakes and their emissaries. Flood irrigation and excess fertilization with manure affect both the hydrology and the chemical quality of surface and groundwater, resulting in diffuse nitrogen pollution. However, studies analyzing the mechanisms linking agricultural practices with vertical and horizontal nitrogen paths are scarce in this area. We investigated groundwater quality and quantity in an unconfined, coarse-grained alluvial aquifer adjacent to the Mincio River (a tributary of the Po River), where steep summer gradients of nitrate (NO<sub>3</sub><sup>−</sup>) concentrations are reported. The effects of manure on solutes’ vertical transport during precipitation events in fertilized and in control soils were simulated under laboratory conditions. The results show high SiO<sub>2</sub> and NO<sub>3</sub><sup>−</sup> leaching in fertilized soils. Similarly, field data are characterized by high SiO<sub>2</sub> and NO<sub>3</sub><sup>−</sup> concentrations, with a comparable spatial distribution but a different temporal evolution, suggesting their common origin but different processes affecting their concentrations in the study area. Our results show that SiO<sub>2</sub> can be used as a conservative tracer of manure spreading, as it does not undergo biogeochemical processes that significantly alter its concentrations. On the contrary, nitrate displays large short-term variations related to aquifer recharge (i.e., flood irrigation and precipitation). In fact, aquifer recharge may promote immediate solubilization and stimulate nitrification, resulting in high NO<sub>3</sub><sup>−</sup> concentrations up to 95.9 mg/L, exceeding the Water Framework Directive (WFD) thresholds. When recharge ends, anoxic conditions likely establish in the saturated zone, favoring denitrification and resulting in a steep decrease in NO<sub>3</sub><sup>−</sup> concentrations.https://www.mdpi.com/2073-4441/12/9/2511groundwaternitrogensilicaflood irrigationagricultural practices |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Edoardo Severini Marco Bartoli Monica Pinardi Fulvio Celico |
spellingShingle |
Edoardo Severini Marco Bartoli Monica Pinardi Fulvio Celico Reactive Silica Traces Manure Spreading in Alluvial Aquifers Affected by Nitrate Contamination: A Case Study in a High Plain of Northern Italy Water groundwater nitrogen silica flood irrigation agricultural practices |
author_facet |
Edoardo Severini Marco Bartoli Monica Pinardi Fulvio Celico |
author_sort |
Edoardo Severini |
title |
Reactive Silica Traces Manure Spreading in Alluvial Aquifers Affected by Nitrate Contamination: A Case Study in a High Plain of Northern Italy |
title_short |
Reactive Silica Traces Manure Spreading in Alluvial Aquifers Affected by Nitrate Contamination: A Case Study in a High Plain of Northern Italy |
title_full |
Reactive Silica Traces Manure Spreading in Alluvial Aquifers Affected by Nitrate Contamination: A Case Study in a High Plain of Northern Italy |
title_fullStr |
Reactive Silica Traces Manure Spreading in Alluvial Aquifers Affected by Nitrate Contamination: A Case Study in a High Plain of Northern Italy |
title_full_unstemmed |
Reactive Silica Traces Manure Spreading in Alluvial Aquifers Affected by Nitrate Contamination: A Case Study in a High Plain of Northern Italy |
title_sort |
reactive silica traces manure spreading in alluvial aquifers affected by nitrate contamination: a case study in a high plain of northern italy |
publisher |
MDPI AG |
series |
Water |
issn |
2073-4441 |
publishDate |
2020-09-01 |
description |
In the northern sector of the Po River Plain (Italy), widespread intensive agriculture and animal farming are supported by large amounts of water from Alpine lakes and their emissaries. Flood irrigation and excess fertilization with manure affect both the hydrology and the chemical quality of surface and groundwater, resulting in diffuse nitrogen pollution. However, studies analyzing the mechanisms linking agricultural practices with vertical and horizontal nitrogen paths are scarce in this area. We investigated groundwater quality and quantity in an unconfined, coarse-grained alluvial aquifer adjacent to the Mincio River (a tributary of the Po River), where steep summer gradients of nitrate (NO<sub>3</sub><sup>−</sup>) concentrations are reported. The effects of manure on solutes’ vertical transport during precipitation events in fertilized and in control soils were simulated under laboratory conditions. The results show high SiO<sub>2</sub> and NO<sub>3</sub><sup>−</sup> leaching in fertilized soils. Similarly, field data are characterized by high SiO<sub>2</sub> and NO<sub>3</sub><sup>−</sup> concentrations, with a comparable spatial distribution but a different temporal evolution, suggesting their common origin but different processes affecting their concentrations in the study area. Our results show that SiO<sub>2</sub> can be used as a conservative tracer of manure spreading, as it does not undergo biogeochemical processes that significantly alter its concentrations. On the contrary, nitrate displays large short-term variations related to aquifer recharge (i.e., flood irrigation and precipitation). In fact, aquifer recharge may promote immediate solubilization and stimulate nitrification, resulting in high NO<sub>3</sub><sup>−</sup> concentrations up to 95.9 mg/L, exceeding the Water Framework Directive (WFD) thresholds. When recharge ends, anoxic conditions likely establish in the saturated zone, favoring denitrification and resulting in a steep decrease in NO<sub>3</sub><sup>−</sup> concentrations. |
topic |
groundwater nitrogen silica flood irrigation agricultural practices |
url |
https://www.mdpi.com/2073-4441/12/9/2511 |
work_keys_str_mv |
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