Tracing freshwater nitrate sources in pre-alpine groundwater catchments using environmental tracers

Stoewer, M.M.; Knöller, Kay; Stumpp, Christine

doi:10.1016/j.jhydrol.2015.03.022

Cited by 37 publications

(19 citation statements)

References 60 publications

(105 reference statements)

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“…Suction cup data covered the frost‐free time period of April through November, whereas precipitation data covered the entire timeframe. Detailed descriptions of site characteristics and installations are found in Stoewer et al (2015). Eleven depth profiles of soil samples were taken during the first ( n = 4) and second ( n = 7) sampling campaigns at a vertical resolution of 10 cm down to maximum depths of 40 to 100 cm using a hand auger (7‐cm diam., Eijkelkamp).…”

Section: Methodsmentioning

confidence: 99%

Correcting for Biogenic Gas Matrix Effects on Laser‐Based Pore Water‐Vapor Stable Isotope Measurements

Gralher

Herbstritt

Weiler

et al. 2018

Vadose Zone Journal

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The isotopic composition (d 2 H, d 18 O) of pore water is an invaluable tracer for the minimally invasive study of subsurface water flow and transport processes. Here, we evaluated a method for pore water isotope analysis that combines laser-based isotope analyzers and water-vapor isotope equilibration using evaporation-proof metalized sample bags. We tested inflation atmospheres (dry air vs. pure N 2 ) and the impact of biogenic gas (CO 2 , CH 4 ) accumulation for storage times of up to 4 wk. Samples were analyzed with a water isotope analyzer (Picarro L2120-i) and a gas chromatograph. Air-inflated water vapor samples showed a greater range of gas matrix effects (d 18 O: 9.63‰; d 2 H: 21.7‰) than N 2 -inflated samples (d 18 O: 7.49‰; d 2 H: 10.6‰) induced by nonuniform buildup of biogenic CO 2 , starting immediately after sample preparation. However, only air-inflated samples could be reliably corrected using instrument-specific sensitivity factors that were empirically determined by interpretation of periodically repeated isotope measurements. Corrected water isotope data were confirmed by similarity with local precipitation and suction cup isotope data. Residual uncertainties were well below the natural variations of soil water isotope values and independent of storage time, thus allowing for consistently reliable interpretations of soil water isotope profiles. We conclude that, especially for pore water sampling that requires small sample volumes and/or long storage times, metalized sample bags should be used to prevent evaporation notwithstanding the enhanced buildup of biogenic gases. Further, if gas matrix effects cannot be excluded, air inflation is preferred over pure N 2 , as only in that case can reliable postcorrections be performed by using internal data only.Abbreviations: CRDS, cavity ring-down spectrometry; DVE-LS, direct vapor equilibration laser spectrometry; GC, gas chromatography; GMWL, global meteoric water line; lc-excess, line-conditioned excess; LMWL, local meteoric water line; LWV, analyzerrecorded line width variable; OA-ICOS, off-axis integrated cavity output spectrometry. Environmental tracers like the isotopic composition of water (d 2 H, d 18 O) haveproven to be valuable tools in hydrology covering all parts of the water cycle. In subsurface hydrology, stable isotopes of water have been successfully applied to determine soil evaporation (Allison, 1982;Braud et al., 2009), groundwater recharge rates and sources (Adomako et al., 2010;Blasch and Bryson, 2007;Koeniger et al., 2016), flow paths (Garvelmann et al., 2012;Stumpp and Hendry, 2012;Uchida et al., 2006), mixing processes (Thomas et al., 2013), transit times (Stumpp et al., 2009;Timbe et al., 2014), root water uptake patterns (Rothfuss and Javaux, 2017), and hydraulic lift (Meunier et al., 2018). Kendall and McDonnell (1998) and Vitvar et al. (2005) presented extensive summaries of stable isotope applications in catchment hydrology. Sprenger et al. (2016) placed special emphasis on pore water isotope applications.In traditional ...

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Section: Methodsmentioning

confidence: 99%

Correcting for Biogenic Gas Matrix Effects on Laser‐Based Pore Water‐Vapor Stable Isotope Measurements

Gralher

Herbstritt

Weiler

et al. 2018

Vadose Zone Journal

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“…Moreover, since shallow GW is commonly impacted by nitrogen from fertilizer used in intensive agriculture (e.g. Stoewer et al 2015), N-limitation in shallow oxic GW will rarely take place. The switch from an N to a P limitation is suggested at N:P ratios of < 3−16 (Keck & Lepori 2012 and references therein).…”

Section: Evidence For Nutrient Limitationmentioning

confidence: 99%

DOM and bacterial growth efficiency in oligotrophic groundwater: absence of priming and co-limitation by organic carbon and phosphorus

Hofmann¹,

Griebler²

2018

Aquat. Microb. Ecol.

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Groundwater ecosystems are low productivity environments due to the small amount and poor quality of organic carbon, and nutrient limitation (N, P). However, field data show the overall presence of degradable DOC. Studies exploring the relationship between carbon properties, nutrient availability and microbial production, as well as possible priming in groundwater are missing. In multi-factorial groundwater batch experiments, we investigated the effect of various organic carbon sources (acetate, organic fertilizer, fulvic acids, humic acids) and nutrients (N, P) to DOC degradation, bacterial production and growth efficiency. Focusing on DOC concentrations, total cell counts, ATP, and bacterial carbon production, our study revealed several important findings. The type of organic carbon offered influenced bacterial growth pattern with lower assimilation efficiencies for the labile but energetically least favorable compound (acetate). Growth on acetate was soon P-limited, while more complex DOM (humic acids) sustained slow but long-term growth. Active but non-growing cells maintained continuous DOC turnover at nutrient limitation. The overall bacterial carbon production and growth efficiency ranged from <1 ng to >1 µg C l −1 h −1 and < 0.1 to 28%, respectively. None of the experiments revealed evidence for priming in ground water. This study is a first attempt to unravel the multiple limitations and energetic constraints facing microbial communities in oligotrophic groundwater. Future studies should evaluate these findings by including the sediment matrix which carries the major fraction of microbial biomass and by looking in more detail at the structural characteristics and availability of DOM and P species.

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“…Oxygen content, total organic carbon (TOC) and nitrate (NO 3 ) are natural tracers indicating fast infiltration and the influence of soil and the unsaturated zone on groundwater quality (Charlier et al 2012;Mudarra et al 2014;Quiers et al 2014). Additionally NO 3 is an indicator for agricultural and thus anthropogenic influenced aquifers (Stoewer et al 2015).…”

Section: Central Gneiss Zonementioning

confidence: 99%

Review: Natural tracers in fractured hard-rock aquifers in the Austrian part of the Eastern Alps—previous approaches and future perspectives for hydrogeology in mountain regions

Hilberg

2016

Hydrogeol J

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Extensive in-depth research is required for the implementation of natural tracer approaches to hydrogeological investigation to be feasible in mountainous regions. This review considers the application of hydrochemical and biotic parameters in mountain regions over the past few decades with particular reference to the Austrian Alps, as an example for alpine-type mountain belts. A brief introduction to Austria's hydrogeological arrangement is given to show the significance of fractured hard-rock aquifers for hydrogeological science as well as for water supply purposes. A literature search showed that research concerning fractured hard-rock aquifers in Austria is clearly underrepresented to date, especially when taking the abundance of this aquifer type and the significance of this topic into consideration. The application of abiotic natural tracers (hydrochemical and isotope parameters) is discussed generally and by means of examples from the Austrian Alps. The potential of biotic tracers (microbiota and meiofauna) is elucidated. It is shown that the meiofauna approach to investigating fractured aquifers has not yet been applied in the reviewed region, nor worldwide. Two examples of new approaches in mountainous fractured aquifers are introduced:(1) use of CO 2 partial pressure and calcite saturation of spring water to reconstruct catchments and flow dynamics (abiotic approach), and, (2) consideration of hard-rock aquifers as habitats to reconstruct aquifer conditions (biotic approach).

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Tracing freshwater nitrate sources in pre-alpine groundwater catchments using environmental tracers

Cited by 37 publications

References 60 publications

Correcting for Biogenic Gas Matrix Effects on Laser‐Based Pore Water‐Vapor Stable Isotope Measurements

Correcting for Biogenic Gas Matrix Effects on Laser‐Based Pore Water‐Vapor Stable Isotope Measurements

DOM and bacterial growth efficiency in oligotrophic groundwater: absence of priming and co-limitation by organic carbon and phosphorus

Review: Natural tracers in fractured hard-rock aquifers in the Austrian part of the Eastern Alps—previous approaches and future perspectives for hydrogeology in mountain regions

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