Assessment of complex subsurface redox structures for sustainable development of agriculture and the environment

Hansen, Birgitte; Voutchkova, Denitza D.; Sandersen, Peter B.E.; Kallesøe, Anders Juhl; Thorling, Lærke; Møller, Ingelise; Madsen, Rasmus Bødker; Jakobsen, Rasmus; Aamand, Jens; Maurya, Pradip Kumar; Kim, Hyojin

doi:10.1088/1748-9326/abda6d

Cited by 16 publications

(14 citation statements)

References 39 publications

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“…The groundwater table monitored at wells around the sampling points confirms that it drops down to 4 m bls and occasionally to 6 m bls in dry years (Supporting Information Figure S2). Madsen et al (2021) also reported a sharp transition from oxic to reduced conditions at around 4−6 m bls in clay till of the quaternary sequence. 22 Altogether, we postulate that the wetting−drying cycle may be responsible for developing the high-denitrification zone in clay till.…”

Section: Resultsmentioning

confidence: 88%

“…Based on the tTEM resistivity model, sediment color, and chemistry of water and the sediment, Madsen et al (2021) proposed that the redox architecture of the quaternary sequence displays a geological window type, while that of the buried valley is a planar type. 22,23 The top surface of the quaternary sequence is covered mainly by clay till with small patches of sandy till (Figure 1b).…”

Section: Methodsmentioning

confidence: 99%

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Upscaling of Denitrification Rates from Point to Catchment Scales for Modeling of Nitrate Transport and Retention

Kim

Jakobsen

Aamand

et al. 2021

Environ. Sci. Technol.

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The spatial and temporal variability of denitrification makes it challenging to integrate conceptual, process-based understandings of nitrate transport and retention into numerical modeling at the catchment scale, although it is critical for the realism and predictive power of the model. In this study, we propose a novel approach where the conceptual understandings of the spatial structure of denitrification zones and the corresponding representative denitrification rates are transformed into a form that can be integrated into a multi-point statistical simulation framework. This is done by constructing a denitrification training image (TI) coupled to a geophysically based TI of the hydrogeological structure. The field observations and laboratory analyses of denitrification rates and the chemistry of water and sediment revealed that the study catchment's subsurface can be characterized by three zones: (1) the oxic zone with no nitrate reduction; (2) the slow-denitrification zone (mean of ln-transformed rate = −1.19 ± 0.52 mg N L −1 yr −1 ); and(3) the high-denitrification zone (mean of ln-transformed rate = 3.86 ± 1.96 mg N L −1 yr −1 ). The underlying controls on the spatial distribution of these zones and the representativeness of denitrification rates were investigated. Then, a TI illustrating the subsurface structure of the denitrification zone was constructed by synthesizing the results of these geochemical interpretations and the hydrogeology TI.

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Section: Resultsmentioning

confidence: 88%

Section: Methodsmentioning

confidence: 99%

Upscaling of Denitrification Rates from Point to Catchment Scales for Modeling of Nitrate Transport and Retention

Kim

Jakobsen

Aamand

et al. 2021

Environ. Sci. Technol.

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“… 35 Denmark is not yet meeting the demands of both national and EU legislations, and more locally targeted mitigation measures are being developed to further lower the nitrate content in groundwater. 36 …”

Section: Discussionmentioning

confidence: 99%

Nitrate in drinking water and risk of birth defects: Findings from a cohort study of over one million births in Denmark

Stayner

Jensen

Schullehner

et al. 2022

The Lancet Regional Health - Europe

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Summary Background A few studies have reported an increased risk of birth defects (BD) with maternal exposure to nitrate in drinking water. We examined this association in a large cohort study with well-characterized exposure. Methods Danish singletons liveborn to Danish-born parents from 1991–2013 were identified using civil and patient registries (n=1,018,914). Exposure to nitrate was estimated using a spatial model based on national data linked with individual addresses. Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated using logistic regression. Findings In total, 33,182 cases of BD were identified. Nitrate concentrations were generally well below US and EU standards. We observed an exposure-response relationship ( p =0·004) between nitrate during pregnancy and eye BD, and increased risk in the highest exposure group (≥25 mg/L nitrate) (OR: 1·29; 95% CI: 1·00, 1·66). An interaction was observed between maternal age and continuous nitrate exposure for nervous system BD ( p <0·001) indicating an increased risk among mothers <25 years-of-age (OR for 10 mg/L (OR 10 ): 1·20; 95% CI: 1·06, 1·35). An interaction (p<0.01) with maternal age and continuous nitrate exposure was also observed for ear, face, and neck BD indicating an increased risk among babies born to mothers <25 years-of-age (OR 10 : 1·35; 95% CI: 1·11, 1·66). There was evidence of an inverse exposure-response relationship for any, digestive system, female genital, and urinary BD. Interpretation Our study is the first to report an association between nitrate and eye BD and BD of the ear, face, and neck. It also provides support to prior reports of increased risk of nervous system BD. Funding This study was supported by a grant from the United States National Institute of Environmental Health Sciences (R01 ES027823-01A1).

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“…Some data are specifically gathered for this study (tTEM and new boreholes; see Fig. 1), while other existing data are freely available through the Danish borehole database "Jupiter" (Hansen and Pjetursson, 2011) and the Danish geophysical database for onshore data "GERDA" (Møller et al,Figure 1. The study area and available data, where (a) displays a digital terrain model, geophysical data and outlined TI areas, (b) an orthophoto (from Geodatastyrelsen, ortophoto forår, WMS Service, March 2021) and geochemical data, and (c) a surface geology map (1 m below surface, Jakobsen and Tougaard, 2020).…”

Section: Methodsmentioning

confidence: 99%

3D multiple-point geostatistical simulation of joint subsurface redox and geological architectures

Madsen

Kim

Kallesøe

et al. 2021

Hydrol. Earth Syst. Sci.

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Abstract. Nitrate contamination of subsurface aquifers is an ongoing environmental challenge due to nitrogen (N) leaching from intensive N fertilization and management on agricultural fields. The distribution and fate of nitrate in aquifers are primarily governed by geological, hydrological and geochemical conditions of the subsurface. Therefore, we propose a novel approach to modeling both geology and redox architectures simultaneously in high-resolution 3D (25m×25m×2m) using multiple-point geostatistical (MPS) simulation. Data consist of (1) mainly resistivities of the subsurface mapped with towed transient electromagnetic measurements (tTEM), (2) lithologies from borehole observations, (3) redox conditions from colors reported in borehole observations, and (4) chemistry analyses from water samples. Based on the collected data and supplementary surface geology maps and digital elevation models, the simulation domain was subdivided into geological elements with similar geological traits and depositional histories. The conceptual understandings of the geological and redox architectures of the study system were introduced to the simulation as training images for each geological element. On the basis of these training images and conditioning data, independent realizations were jointly simulated of geology and redox inside each geological element and stitched together into a larger model. The joint simulation of geological and redox architectures, which is one of the strengths of MPS compared to other geostatistical methods, ensures that the two architectures in general show coherent patterns. Despite the inherent subjectivity of interpretations of the training images and geological element boundaries, they enable an easy and intuitive incorporation of qualitative knowledge of geology and geochemistry in quantitative simulations of the subsurface architectures. Altogether, we conclude that our approach effectively simulates the consistent geological and redox architectures of the subsurface that can be used for hydrological modeling with nitrogen (N) transport, which may lead to a better understanding of N fate in the subsurface and to future more targeted regulation of agriculture.

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Assessment of complex subsurface redox structures for sustainable development of agriculture and the environment

Cited by 16 publications

References 39 publications

Upscaling of Denitrification Rates from Point to Catchment Scales for Modeling of Nitrate Transport and Retention

Upscaling of Denitrification Rates from Point to Catchment Scales for Modeling of Nitrate Transport and Retention

Nitrate in drinking water and risk of birth defects: Findings from a cohort study of over one million births in Denmark

3D multiple-point geostatistical simulation of joint subsurface redox and geological architectures

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