| Abstract | In permeable soils, excess nitrate from agriculture is transported vertically and accumulates in aquifers.
However, it can come back to the surface via groundwater movement and pollute watercourses. We
hypothesized that vegetated ditches may mitigate significant amounts of nitrate from spring waters, and
represent a buffer system to protect downstream water bodies from eutrophication. To test this hypothesis,
nitrate removal was measured in ditches fed by nitrate-rich groundwater in presence and absence of emergent
vegetation. Reach-scale methods (N2 open-channel, N budgets) were coupled with laboratory incubations of
sediment cores (benthic N fluxes, isotope pairing) and plant N uptake estimation. Studied ditches are
representative of a wide hydrological network in Northern Italy, within the so-called "spring-belt" (Po River
plain), a NO3
--vulnerable area with high density of contaminated springs. Results indicated a greater reachscale
N removal in vegetated (38-84 mmol N m-2 d-1) as compared to unvegetated condition
(12-45 mmol N m-2 d-1). Denitrification was the dominant N-removal pathway, while plant uptake represented
a minor fraction of the net N abatement. Large development of interfaces for microbial growth provided
by aquatic vegetation and more opportunities for biotic interactions are features that promote nitrate reduction
in the ditch network. Despite the vegetated ditches were significant N-reactors, denitrification provided a little
N-removal to in-stream high nitrate loads, with the exception of periods when plant coverage and water
retention time peaked. Management of N-saturated ditches may consist in the enlargement of stretches to
increase water retention and amplify the interfaces where biofilms develop, though preserving hydraulic
efficiency. The maintenance of vegetation in the ditch networks would result in a significant N-abatement on a
larger scale. |
| Text | 372979 2017 10.1016/j.agee.2017.04.004 Scopus 2 s2.0 85018511679 ISI Web of Science WOS 000401391100009 Ditch network Nitrate pollution Springs Denitrification Mitigation of nitrogen pollution in vegetated ditches fed by nitrate rich spring waters Soana E.; Balestrini R.; Vincenzi F.; Bartoli M.; Castaldelli G. Department of Life Sciences and Biotechnology, University of Ferrara, Via L. Borsari 46, Ferrara, 44121, , Italy; Water Research Institute, National Research Council IRSA CNR , Via del Mulino 19, Brugherio, MB, 20861, , , Italy; Water Research Institute, National Research Council IRSA CNR , Via del Mulino 19, Brugherio, MB, 20861, , , Italy; Department of Chemistry, Life Sciences and Environmental Sustainability, University of Parma, Viale G.P. Usberti 33/A, Parma, 43124, , Italy; Marine Science and Technology Center, University of Klaipeda, H. Manto 84 st, Klaipeda, , Lithuania In permeable soils, excess nitrate from agriculture is transported vertically and accumulates in aquifers. However, it can come back to the surface via groundwater movement and pollute watercourses. We hypothesized that vegetated ditches may mitigate significant amounts of nitrate from spring waters, and represent a buffer system to protect downstream water bodies from eutrophication. To test this hypothesis, nitrate removal was measured in ditches fed by nitrate rich groundwater in presence and absence of emergent vegetation. Reach scale methods N2 open channel, N budgets were coupled with laboratory incubations of sediment cores benthic N fluxes, isotope pairing and plant N uptake estimation. Studied ditches are representative of a wide hydrological network in Northern Italy, within the so called spring belt Po River plain , a NO3 vulnerable area with high density of contaminated springs. Results indicated a greater reachscale N removal in vegetated 38 84 mmol N m 2 d 1 as compared to unvegetated condition 12 45 mmol N m 2 d 1 . Denitrification was the dominant N removal pathway, while plant uptake represented a minor fraction of the net N abatement. Large development of interfaces for microbial growth provided by aquatic vegetation and more opportunities for biotic interactions are features that promote nitrate reduction in the ditch network. Despite the vegetated ditches were significant N reactors, denitrification provided a little N removal to in stream high nitrate loads, with the exception of periods when plant coverage and water retention time peaked. Management of N saturated ditches may consist in the enlargement of stretches to increase water retention and amplify the interfaces where biofilms develop, though preserving hydraulic efficiency. The maintenance of vegetation in the ditch networks would result in a significant N abatement on a larger scale. 243 Published version http //www.scopus.com/record/display.url eid=2 s2.0 85018511679 origin=inward Mitigation of nitrogen pollution in vegetated ditches fed by nitrate rich spring waters Soanaetal.2017.pdf Articolo in rivista Elsevier 0167 8809 Agriculture, ecosystems environment Print Agriculture, ecosystems environment Print Agric. ecosyst. environ. Print Agriculture, ecosystems environment. Print Agriculture, ecosystems and environment Print raffaella.balestrini BALESTRINI RAFFAELLA |
