Contaminant mass discharge estimation in groundwater based on multi-level point measurements: A numerical evaluation of expected errors

Kübert, Markus; Finkel, Michael

doi:10.1016/j.jconhyd.2005.12.003

Cited by 52 publications

(39 citation statements)

References 33 publications

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“…Contaminant flux can prove that natural attenuation occurs on a site but does not differentiate between dilution and denitrification. Contaminant mass flux across a transect of wells, known as a control plane, has been used to quantify the contaminant load leaving a system (Basu et al, 2006;Bockelmann et al, 2001Bockelmann et al, , 2003Brusseau et al, 2007;Campbell et al, 2006;Duncan et al, 2007;Hatfield et al, 2004;Kubert and Finkel, 2006). This method allows a quantifiable load of NO 3 -N leaving a system to be calculated, rather than focusing on a point where shallow groundwater exceeds target or legislative concentration limits such as 11.3 mg NO 3 -N L…”

Section: Introductionmentioning

confidence: 99%

Factors affecting nitrate distribution in shallow groundwater under a beef farm in South Eastern Ireland

Fenton

Richards

Kirwan

et al. 2009

Journal of Environmental Management

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a b s t r a c tGroundwater contamination was characterised using a methodology which combines shallow groundwater geochemistry data from 17 piezometers over a 2 yr period in a statistical framework and hydrogeological techniques. Nitrate-N (NO 3 -N) contaminant mass flux was calculated across three control planes (rows of piezometers) in six isolated plots. Results showed natural attenuation occurs on site although the method does not directly differentiate between dilution and denitrification. It was further investigated whether NO 3 -N concentration in shallow groundwater (<5 m below ground level) generated from an agricultural point source on a 4.2 ha site on a beef farm in SE Ireland could be predicted from saturated hydraulic conductivity (K sat ) measurements, ground elevation (m Above Ordnance Datum), elevation of groundwater sampling (screen opening interval) (m AOD) and distance from a dirty water point pollution source. Tobit regression, using a background concentration threshold of 2.6 mg NO 3 -N L À1 showed, when assessed individually in a step wise procedure, K sat was significantly related to groundwater NO 3 -N concentration. Distance of the point dirty water pollution source becomes significant when included with K sat in the model. The model relationships show areas with higher K sat values have less time for denitrification to occur, whereas lower K sat values allow denitrification to occur. Areas with higher permeability transport greater NO 3 -N fluxes to ground and surface waters. When the distribution of Cl À was examined by the model, K sat and ground elevation had the most explanatory power but K sat was not significant pointing to dilution having an effect. Areas with low NO 3 concentration and unaffected Cl À concentration points to denitrification, low NO 3 concentration and low Cl À chloride concentration points to dilution and combining these findings allows areas of denitrification and dilution to be inferred. The effect of denitrification is further supported as mean groundwater NO 3 -N was significantly (P < 0.05) related to groundwater N 2 /Ar ratio, redox potential (Eh), dissolved O 2 and N 2 and was close to being significant with N 2 O (P ¼ 0.08). Calculating contaminant mass flux across more than one control plane is a useful tool to monitor natural attenuation. This tool allows the identification of hot spot areas where intervention other than natural attenuation may be needed to protect receptors.

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Section: Introductionmentioning

confidence: 99%

Factors affecting nitrate distribution in shallow groundwater under a beef farm in South Eastern Ireland

Fenton

Richards

Kirwan

et al. 2009

Journal of Environmental Management

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“…In most cases, point measurements of contaminant concentrations at discrete times in selected monitoring wells usually do not allow drawing conclusions concerning contaminant fluxes in the urban areas. Therefore, flux calculations are necessary to perform a meaningful risk analysis and to select viable remediation measures (see also Kübert and Finkel 2006;Rein et al 2009). …”

Section: General Considerationsmentioning

confidence: 99%

Mass fluxes of xenobiotics below cities: challenges in urban hydrogeology

et al. 2010

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Urban areas are the focus of major ecological, social and economical activity. They are thus also prime locations of increasing conflict with regard to water use and water protection. As a direct and/or indirect consequence of urban land use and human activity, urban water systems are frequently polluted with organic contaminants including waste water-born xenobiotics such as pharmaceuticals, personal care products (collectively known as PPCPs) and endocrine-active substances. This study reviews new integrated methodologies including flux calculations as well as chemical investigations for determining the impact of human activities on urban water systems and on processes within the urban watershed. The use of indicator substances, representing different contaminant sources and pathways, integral pumping tests and mass balance approaches are suitable alternatives within these environments. The issues are explored using contaminant mass balance examples from Halle/Saale and Leipzig, Germany.

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“…Specific methods used to measure J and ṁ have been summarized in several publications (e.g., Chen et al, 2014;ITRC, 2010;Kavanaugh et al, 2011;Kübert and Finkel, 2006), and can be divided into two broad categories: pointmeasurement methods and pumping-measurement methods. Point-measurement methods are based on sampling techniques with relatively small sampling volumes, and most often consist either of applications based on multi-level samplers (e.g., Freitas et al, 2011;Guilbeault et al, 2005;Kao and Wang, 2001) or passive flux meters (PFMs) (e.g., Annable et al, 2005;Hatfield et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

“…A number of studies have been completed on pointmeasurement method uncertainty (Béland-Pelletier et al, 2011;Cai et al, 2011Cai et al, , 2012Chen et al, 2014;Klammler et al, 2012;Kübert and Finkel, 2006;Li and Abriola, 2009;Li et al, 2007;MacKay et al, 2012;Schwede and Cirpka, 2010;Troldborg et al, 2010Troldborg et al, , 2012. Two of these studies were based on field trials (Béland-Pelletier et al, 2011;MacKay et al, 2012), two of the studies used flow and transport simulations within Monte Carlo frameworks (Chen et al, 2014;Kübert and Finkel, 2006); two more studies likewise used flow and transport simulations within Monte Carlo frameworks, but simulations were conditioned to field data (Schwede and Cirpka, 2010;Troldborg et al, 2010); and the remaining studies employed various conditional, geostatistical techniques, wherein one or more parameters across the control plane were treated as spatial random variables.…”

Section: Introductionmentioning

confidence: 99%

“…Two of these studies were based on field trials (Béland-Pelletier et al, 2011;MacKay et al, 2012), two of the studies used flow and transport simulations within Monte Carlo frameworks (Chen et al, 2014;Kübert and Finkel, 2006); two more studies likewise used flow and transport simulations within Monte Carlo frameworks, but simulations were conditioned to field data (Schwede and Cirpka, 2010;Troldborg et al, 2010); and the remaining studies employed various conditional, geostatistical techniques, wherein one or more parameters across the control plane were treated as spatial random variables. Kubert and Finkel (2006) conducted an extensive Monte Carlo analysis on a hypothetical site to evaluate uncertainty as a function of measurement method, sampling density (S D ), and hydraulic conductivity (K) heterogeneity.…”

Section: Introductionmentioning

confidence: 99%

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Screening-level estimates of mass discharge uncertainty from point measurement methods

Brooks

Young

Wood

et al. 2015

Journal of Contaminant Hydrology

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The uncertainty of mass discharge measurements associated with point-scale measurement techniques was investigated by deriving analytical solutions for the mass discharge coefficient of variation for two simplified, conceptual models. In the first case, a depth-averaged domain was assumed, consisting of one-dimensional groundwater flow perpendicular to a one-dimensional control plane of uniformly spaced sampling points. The contaminant flux along the control plane was assumed to be normally distributed. The second case consisted of one-dimensional groundwater flow perpendicular to a two-dimensional control plane of uniformly spaced sampling points. The contaminant flux in this case was assumed to be distributed according to a bivariate normal distribution. The center point for the flux distributions in both cases was allowed to vary in the domain of the control plane as a uniform random variable. Simplified equations for the uncertainty were investigated to facilitate screening-level evaluations of uncertainty as a function of sampling network design. Results were used to express uncertainty as a function of the length of the control plane and number of wells, or alternatively as a function of the sample spacing. Uncertainty was also expressed as a function of a new dimensionless parameter, Ω, defined as the ratio of the maximum local flux to the product of mass discharge and sample density. Expressing uncertainty as a function of Ω provided a convenient means to demonstrate the relationship between uncertainty, the magnitude of a local hot spot, magnitude of mass discharge, distribution of the contaminant across the control plane, and the sampling density.

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Contaminant mass discharge estimation in groundwater based on multi-level point measurements: A numerical evaluation of expected errors

Cited by 52 publications

References 33 publications

Factors affecting nitrate distribution in shallow groundwater under a beef farm in South Eastern Ireland

Factors affecting nitrate distribution in shallow groundwater under a beef farm in South Eastern Ireland

Mass fluxes of xenobiotics below cities: challenges in urban hydrogeology

Screening-level estimates of mass discharge uncertainty from point measurement methods

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