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| Titel |
Mobilisation or dilution? Nitrate response of karst springs to high rainfall events |
| VerfasserIn |
M. Huebsch, O. Fenton, B. Horan, D. Hennessy, K. G. Richards, P. Jordan, N. Goldscheider, C. Butscher, P. Blum |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 18, no. 11 ; Nr. 18, no. 11 (2014-11-05), S.4423-4435 |
| Datensatznummer |
250120520
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| Publikation (Nr.) |
 copernicus.org/hess-18-4423-2014.pdf |
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| Zusammenfassung |
| Nitrate (NO3−) contamination of groundwater associated with
agronomic activity is of major concern in many countries. Where agriculture,
thin free draining soils and karst aquifers coincide, groundwater is highly
vulnerable to nitrate contamination. As residence times and
denitrification potential in such systems are typically low, nitrate can
discharge to surface waters unabated. However, such systems also react
quickest to agricultural management changes that aim to improve water
quality. In response to storm events, nitrate concentrations can alter
significantly, i.e. rapidly decreasing or increasing concentrations. The
current study examines the response of a specific karst spring situated on a
grassland farm in South Ireland to rainfall events utilising high-resolution
nitrate and discharge data together with on-farm borehole groundwater
fluctuation data. Specifically, the objectives of the study are to formulate
a scientific hypothesis of possible scenarios relating to nitrate
responses during storm events, and to verify this hypothesis using
additional case studies from the literature. This elucidates the controlling
key factors that lead to mobilisation and/or dilution of nitrate
concentrations during storm events. These were land use, hydrological
condition and karstification, which in combination can lead to differential
responses of mobilised and/or diluted nitrate concentrations. Furthermore,
the results indicate that nitrate response in karst is strongly dependent on
nutrient source, whether mobilisation and/or dilution occur and on the pathway
taken. This will have consequences for the delivery of nitrate to a surface
water receptor. The current study improves our understanding of nitrate
responses in karst systems and therefore can guide environmental modellers,
policy makers and drinking water managers with respect to the regulations of
the European Union (EU) Water Framework Directive (WFD). In future, more
research should focus on the high-resolution monitoring of karst aquifers to
capture the high variability of hydrochemical processes, which occur at time
intervals of hours to days. |
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