Groundwater-derived contaminant fluxes along a channelized Coastal Plain stream

LaSage, Danita M.; Fryar, Alan E.; Mukherjee, Abhijit; Sturchio, Neil C.; Heraty, Linnea J.

doi:10.1016/j.jhydrol.2008.07.026

Cited by 10 publications

(18 citation statements)

References 42 publications

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“…In addition, 99 Tc concentrations decreased more than TCE concentrations did. The linear regression between the analytes in springs was TCE = 1.1 99 Tc + 8.9 ( r 2 = 0.86) for 1999 to 2001 (LaSage et al 2008a) and, considering samples where both analytes were above detection limit, TCE = 3.0 99 Tc − 14 ( r 2 = 0.91) for 2011 to 2012 (Figure 7).…”

Section: Discussionmentioning

confidence: 97%

“…Groundwater in the RGA is contaminated by TCE, which was used as a degreasing solvent at PGDP from 1953 to 1993, and by technetium‐99 ( 99 Tc), a radionuclide that was a byproduct of reprocessed uranium oxide use from 1953 to 1976 (Clausen et al 1992; LaSage et al 2008a). The Safe Drinking Water Act sets a maximum contaminant level (MCL) of 5 μg/L for TCE, while 99 Tc (a beta emitter with a half‐life of 2.1 × 10 5 years) has a site‐derived MCL of 900 pCi/L.…”

Section: Study Area Backgroundmentioning

confidence: 99%

“…Concentrations in the suspected source areas approached the solubility limit for TCE (1100 mg/L, which is indicative of residual amounts of dense, nonaqueous phase liquid) and 40,000 pCi/L for 99 Tc. LaSage et al (2008a) reported maximum concentrations of 450 μg/L for TCE and 461 pCi/L for 99 Tc in springs, and a maximum TCE concentration of 1691 μg/L in a peeper (passive‐diffusion sampler) beneath the streambed, where the northwest plume passes beneath Little Bayou Creek. There is no evidence that the northeast plume impacts water quality in Little Bayou Creek (LaSage et al 2008a).…”

Section: Study Area Backgroundmentioning

confidence: 99%

“…LaSage et al (2008a) reported maximum concentrations of 450 μg/L for TCE and 461 pCi/L for 99 Tc in springs, and a maximum TCE concentration of 1691 μg/L in a peeper (passive‐diffusion sampler) beneath the streambed, where the northwest plume passes beneath Little Bayou Creek. There is no evidence that the northeast plume impacts water quality in Little Bayou Creek (LaSage et al 2008a). Pump‐and‐treat systems were implemented for contaminant removal in the northwest plume in August 1995 (U.S. Department of Energy 2007).…”

Section: Study Area Backgroundmentioning

confidence: 99%

See 3 more Smart Citations

Seasonal to Decadal Variability in Focused Groundwater and Contaminant Discharge along a Channelized Stream

Tripathi¹,

Fryar²,

Hampson³

et al. 2020

Groundwater Monitoring Rem

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Focused groundwater discharge to streams is problematic at contaminated sites because high fluxes can limit natural attenuation in the hyporheic zone. However, information on location, spatial evolution, and temporal persistence of springs in unlithified sediments over multiyear time scales is limited. We examine discharge at point (~1‐m) to reach (~300‐m) scales along a stream that intercepts trichloroethene and technetium‐99 plumes from a Superfund site. During 2011 to 2012, we seasonally monitored stream and spring flow and contaminant concentrations, along with probing streambed temperatures on a grid in winter and summer, building on prior monitoring during 1999 to 2002. Baseflow measured by both gauging and dye dilution generally increased with distance downstream, and stream and spring discharge varied seasonally, from minima in October to January to maxima in February to June. Thermal anomalies identified by probing occupied approximately 3% to 6% of the reach and typically coincided with visible springs or seeps. Locations of anomalies were similar to those identified in summer 2002, although some orifices disappeared and others emerged. Vertical groundwater fluxes calculated from probing tended to be less than net fluxes calculated from stream discharge, perhaps in part because the assumption of one‐dimensional, steady‐state flow in calculating point fluxes was simplistic. Maximum contaminant concentrations and fluxes decreased between 1999 to 2001 and 2011 to 2012 as a result of partial capture by an upgradient pump‐and‐treat system. Our findings confirm that springs in unlithified sediments can remain stationary within a few meters over decadal time scales, and seasonal variability in discharge can be greater than decadal variability.

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Section: Discussionmentioning

confidence: 97%

Section: Study Area Backgroundmentioning

confidence: 99%

Section: Study Area Backgroundmentioning

confidence: 99%

Section: Study Area Backgroundmentioning

confidence: 99%

See 2 more Smart Citations

Seasonal to Decadal Variability in Focused Groundwater and Contaminant Discharge along a Channelized Stream

Tripathi¹,

Fryar²,

Hampson³

et al. 2020

Groundwater Monitoring Rem

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“…Notably, a few studies apply the in‐stream CMD methodology at several points in time to investigate the groundwater contribution and fate of CAHs (and other dissolved contaminants) in streams (Heejung and Hemond ; LaSage et al. ; Milosevic et al. ; Rønde et al.…”

Section: Introductionmentioning

confidence: 99%

Evidence of Spatio‐Temporal Variations in Contaminants Discharging to a Peri‐Urban Stream

Lemaire

McKnight

Schulz

et al. 2020

Groundwater Monitoring Rem

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Xenobiotic organic compounds can be discharged from contaminated groundwater inflow and may seep into streams from multiple pathways with very different dynamics, some not fully understood. In this study, we investigated the spatio‐temporal variation of chlorinated ethenes discharging from a former industrial site (with two main contaminant sources, A and B) into a stream system in a heterogeneous clay till setting in eastern Denmark. The investigated reach and near‐stream surroundings are representative of peri‐urban settings, with a mix of high channel alteration and more natural stream environment. We therefore propose an approach for risk assessing impacts arising from such complex contamination patterns, accounting for potential spatio‐temporal fluctuations and presence of multiple pathways. Our study revealed substantial variations in pathway contributions and overall contaminant mass discharge to the stream. Variable contaminant contributions arising from both groundwater seepage and urban drains were identified in the channelized part of the north stream, primarily from source A. Furthermore, variations in the hyporheic and shallow groundwater flows were found to enhance contaminant transport from source B. These processes result in an increase of the overall mass of contaminant discharged, correlating with the channels' flow. Thus, an in‐stream control plane approach was found to be an effective method for integrating multiple and variable discharge contributions quantitatively, although information on specific contaminant sources is lost. This study highlights the complexity and variability of contaminant fluxes occurring at the interface between groundwater and peri‐urban streams, and calls for the consideration of these variations when designing monitoring programs and remedial actions for contaminated sites with the potential to impact streams.

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2012

Water‐Quality Engineering in Natural Systems

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Groundwater-derived contaminant fluxes along a channelized Coastal Plain stream

Cited by 10 publications

References 42 publications

Seasonal to Decadal Variability in Focused Groundwater and Contaminant Discharge along a Channelized Stream

Seasonal to Decadal Variability in Focused Groundwater and Contaminant Discharge along a Channelized Stream

Evidence of Spatio‐Temporal Variations in Contaminants Discharging to a Peri‐Urban Stream

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