Quantification of Phosphorus Transport from a Karstic Agricultural Watershed to Emerging Spring Water

Mellander, Per‐Erik; Jordan, Phillip; Melland, Alice R.; Murphy, Paul; Wall, David P.; Mechan, S.; Meehan, R.J.; Kelly, Coran; Shine, O.; Shortle, G.

doi:10.1021/es304909y

Cited by 53 publications

(53 citation statements)

References 33 publications

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“…Thus, while the sources of P could be equally as widespread, its ability to reach the groundwater is highly variable. However, once in the conduit system, P is known to be transported conservatively with negligible attenuation (Mellander et al, 2013;Kilroy and Coxon, 2005).…”

Section: Groundwatermentioning

confidence: 99%

Quantifying the influence of surface water–groundwater interaction on nutrient flux in a lowland karst catchment

McCormack

Naughton

Johnston

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. Nutrient contamination of surface waters and groundwaters is an issue of growing importance as the risks associated with agricultural run-off escalate due to increasing demands on global food production. In this study, the influence of surface water-groundwater interaction on the nutrient flux in a lowland karst catchment was investigated with the aid of alkalinity sampling and a hydrological model. The objective of the study was to determine the impact of ephemeral karst lakes (turloughs) on the surface watergroundwater nutrient flux, and whether these lakes act as sources or sinks of nutrients within the groundwater flow system. Water samples were tested from a variety of rivers, turloughs, boreholes and springs at monthly intervals over 3 years. Alkalinity sampling was used to elucidate the contrasting hydrological functioning between different turloughs. Such disparate hydrological functioning was further investigated with the aid of a hydrological model which allowed for an estimate of allogenically and autogenically derived nutrient loading into the karst system. The model also allowed for an investigation of mixing within the turloughs, comparing observed behaviours with the hypothetical conservative behaviour allowed for by the model. Within the turloughs, recorded nutrient concentrations were found to reduce over the flooded period, even though the turloughs hydrological functioning (and the hydrological model) suggested this would not occur under conservative conditions. As such, it was determined that nutrient loss processes were occurring within the system. Denitrification during stable flooded periods (typically 3-4 months per year) was deemed to be the main process reducing nitrogen concentrations within the turloughs, whereas phosphorus loss is thought to occur mostly via sedimentation and subsequent soil deposition.The results from this study suggest that, in stable conditions, ephemeral lakes can impart considerable nutrient losses on a karst groundwater system.

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Section: Groundwatermentioning

confidence: 99%

Quantifying the influence of surface water–groundwater interaction on nutrient flux in a lowland karst catchment

McCormack

Naughton

Johnston

et al. 2016

Hydrol. Earth Syst. Sci.

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“…In recent years, high-resolution monitoring in karst catchments over extended periods of time has received greater attention (Mellander et al, 2013;Schwientek et al, 2013). Also, spectrophotometrical ultraviolet/visible (UV/VIS) light monitoring, which was originally developed for monitoring waste water treatment plants (Drolc and Vrtovšek, 2010), has been applied to karst springs to continuously monitor nitrate concentrations (Grimmeisen et al, 2012;Pu et al, 2011).…”

Section: Huebsch Et Al: Nitrate Response Of Karst Springs To Highmentioning

confidence: 99%

Mobilisation or dilution? Nitrate response of karst springs to high rainfall events

Huebsch

Fenton

Horan

et al. 2014

Hydrol. Earth Syst. Sci.

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Abstract. Nitrate (NO −3 ) 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 onfarm 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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“…Similarly the complexities of phosphate sources (Holman et al, 2010) and mobility (Lapworth et al, 2011;Mellander et al, 2013) have been outside the scope of this study.…”

Section: Applicability Of the Results To Other Catchmentsmentioning

confidence: 98%

Groundwater conceptual models: implications for evaluating diffuse pollution mitigation measures

Allen

Darling

Davies

et al. 2014

QJEGH

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The Water Framework Directive (WFD) identifies diffuse pollution as a long-term threat to water quality. Farming contributes significantly to this pollution. There is a clear need for mitigation measures and assessment of their efficacy. Accordingly, Demonstration Test Catchments (DTCs) have been established in England to test the effectiveness of changes in agricultural practice on river water quality and ecology. However, the presence of groundwater in these hydrological systems implies a wide range of travel times for pollutants from source to receptor. Unless flow routes are better characterised, it will be difficult to gauge the success of control measures in the short-term.Using 3D modelling and supplementary hydrochemical information, this study considers the hydrogeology of several sub-catchments in the Avon DTC, southern England. Data suggest that groundwater ages >25 years exist in parts of the catchments; clearly observations like these must be used to judge the likely effectiveness of targeted control measures. The revealed hydrogeological complexity of the Avon catchment is unlikely to be unique, so the techniques described here should be applicable to other lowland river systems with moderate-to-high baseflow indices (>0.5). To support the WFD, groundwater conceptual models should inform the design of effective measures for diffuse pollution mitigation..

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Quantification of Phosphorus Transport from a Karstic Agricultural Watershed to Emerging Spring Water

Cited by 53 publications

References 33 publications

Quantifying the influence of surface water–groundwater interaction on nutrient flux in a lowland karst catchment

Quantifying the influence of surface water–groundwater interaction on nutrient flux in a lowland karst catchment

Mobilisation or dilution? Nitrate response of karst springs to high rainfall events

Groundwater conceptual models: implications for evaluating diffuse pollution mitigation measures

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