Spatiotemporal controls on septic system derived nutrients in a nearshore aquifer and their discharge to a large lake

Rakhimbekova, Sabina; O'Carroll, D. M.; Oldfield, Lauren E.; Ptacek, Carol J.; Robinson, C. E.

doi:10.1016/j.scitotenv.2020.141262

Cited by 21 publications

(24 citation statements)

References 65 publications

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“…Prior field measurements (groundwater wells, vertical hydraulic gradient measurements using potentio-manometers, and pressure transducer arrays) and numerical simulations have shown that the groundwater flow conditions at sites 1 and 2 are characterized by a net lakeward groundwater flow with a zone of recirculating lake water around the shoreline. 8,24,45 The zone of recirculating lake water extends from the shoreline to 3−10 m offshore and up to 2 m deep depending on the prevailing wave conditions. 8,24,45 Based on groundwater table measurements at sites 3, 4, 5, and 6, it is expected that similar groundwater flow conditions also exist at these other sites.…”

Section: Resultsmentioning

confidence: 99%

“…8,24,45 The zone of recirculating lake water extends from the shoreline to 3−10 m offshore and up to 2 m deep depending on the prevailing wave conditions. 8,24,45 Based on groundwater table measurements at sites 3, 4, 5, and 6, it is expected that similar groundwater flow conditions also exist at these other sites. ORP was not measured at sites 4, 5, and 6, but the general redox conditions may be inferred based on the presence of redox sensitive dissolved species.…”

Section: Resultsmentioning

confidence: 99%

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Occurrence of Arsenic in Nearshore Aquifers Adjacent to Large Inland Lakes

Rakhimbekova

O'Carroll

Robinson

2021

Environ. Sci. Technol.

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Metal oxides that form near sediment−water interfaces in marine and riverine settings are known to act as a sediment trap for pollutants of environmental concern (e.g., arsenic and mercury). The occurrence of these pollutant traps near sediment−water interfaces in nearshore lake environments is unclear yet important to understand because they may accumulate pollutants that may be later released as environmental conditions change. This study evaluates the prevalence of pollutant sediment traps in nearshore aquifers adjacent to large lakes and the factors that affect the accumulation and release of pollutants, specifically arsenic. Field data from six sites along the Laurentian Great Lakes indicate widespread enrichment of arsenic in nearshore aquifers with arsenic sequestered to iron oxide phases. Arsenic enrichment at all sites (solid-phase arsenic >2 μg/g) suggests that this is a naturally occurring phenomenon. Arsenic was more mobile in reducing aquifers with elevated dissolved arsenic (up to 60 μg/L) observed, where reducing groundwater mixes with infiltrating oxic lake water. Dissolved arsenic was low (<3 μg/L) in all oxic nearshore aquifers studied despite high solid-phase arsenic concentrations. The findings have broad implications for understanding the widespread accumulation of reactive pollutants in nearshore aquifers and factors that affect their release to large lakes.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Occurrence of Arsenic in Nearshore Aquifers Adjacent to Large Inland Lakes

Rakhimbekova

O'Carroll

Robinson

2021

Environ. Sci. Technol.

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“…Travel times of 50 years and greater for these flows paths also highlight the legacy issue associated with LGD with delay between land application of pollutants (e.g., nutrients) and the ultimate discharge of the pollutants to the lake. It is also important to note that travel times for many pollutants may be considerably longer than the groundwater travel times due to retardation (Lewandowski et al, 2015;Rakhimbekova et al, 2021).This may have potential long term implications for lake water quality. Moreover, it means that the current management efforts targeted at reducing pollutant inputs to the lake may be buffered by the long travel times for pollutants to reach the lake via LGD.…”

Section: Reasons For Discrepancies Between Lgd Estimatesmentioning

confidence: 99%

“…To address lake water quality impairment, there is increasing need to identify, quantify, and manage all the sources and pathways delivering pollutants to lakes. While often overlooked, groundwater discharge can be an important delivery pathway for lakes (Knights et al, 2017; Lewandowski et al, 2015; Meinikmann et al, 2015; Rakhimbekova et al, 2018; Rakhimbekova et al, 2021; Rosenberry et al, 1999). Groundwater can enter a lake either directly from an aquifer, termed lacustrine groundwater discharge (LGD), or indirectly through groundwater‐fed streams that flow into the lake (termed indirect groundwater discharge) (Grannemann et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

Evaluating lacustrine groundwater discharge to a large glacial lake using regional scale radon‐222 surveys and groundwater modelling

Wallace

Wexler²,

Malott³

et al. 2021

Hydrological Processes

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Lacustrine groundwater discharge (LGD) can be an important pathway for delivering pollutants to lakes but this pathway is often poorly characterized. Evaluating the potential impact of LGD on lake water quality requires understanding the magnitude and spatial variability of LGD, as well as understanding the age and flow paths of the discharging groundwater (e.g., recharge area, groundwater flow paths, and travel times). This study first compares LGD rates along two $40 km shoreline lengths of a large glacial lake, Lake Simcoe, Canada, that were independently estimated via a radon-222 ( 222 Rn) field survey and via regional scale groundwater-surface water modelling. Backward particle tracking analysis is then used to examine the age and flow paths of the LGD and thereby assess the potential for the LGD to deliver anthropogenic pollutants to the lake. The field and modelling results compare well with respect to the magnitude and spatial variability ofLGD. However, the comparison highlights the need for well-defined hydrogeological characterization if regional scale models are to be applied for LGD estimation. The particle tracking analysis indicates large variation in the groundwater flow path lengths and travels times (>1000 years to <50 years) for LGD along the shoreline. This illustrates that the LGD along different shoreline areas has varying potential to deliver anthropogenic pollutants to the lake. The study findings demonstrate the benefits of comparing independent field measured and model-simulated LGD estimates, and moreover suggest that it may be possible, in some cases, to use existing regional scale groundwater-surface water models, purpose-built for other water resource and quality objectives, to conduct preliminary evaluation of LGD contributions to lakes. Preliminary model-based evaluation would enable field efforts aiming to quantify and manage LGD to be better targeted rather than relying solely on regional scale field techniques that are often highly resource intensive.

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“…A potential solution lies with the measurement of artificial sweeteners (AS). AS have been used as tracers in groundwater and surface water for modern wastewater, whether it be by leaky sewers or inputs from on-site septic systems (Buerge et al 2009;Van Stempvoort et al 2011;Roy and Bickerton 2012;Robertson et al 2013;Tran et al 2014;Spoelstra et al 2017;Oldfield et al 2020;Rakhimbekova et al 2021) and for landfills (Roy et al 2014;Stefania et al 2019;Propp et al 2021). Roy et al (2014) showed that old landfills (those closed 1960s to early 1990s) only contained saccharin (SAC) and, less frequently, cyclamate (CYC), whereas modern landfills also contained acesulfame (ACE) and sucralose (SUC).…”

Section: Introductionmentioning

confidence: 99%

Artificial Sweeteners Identify Spatial Patterns of Historic Landfill Contaminated Groundwater Discharge in an Urban Stream

Propp

Brown

Collins

et al. 2021

Groundwater Monitoring Rem

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This column reviews the general features of PHT3D Version 2, a reactive multicomponent transport model that couples the geochemical modeling software PHREEQC-2 (Parkhurst and Appelo 1999) with three-dimensional groundwater flow and transport simulators MODFLOW-2000 and MT3DMS (Zheng and Wang 1999). The original version of PHT3D was developed by Henning Prommer and Version 2 by Henning Prommer and Vincent Post (Prommer and Post 2010). More detailed information about PHT3D is available at the website http://www.pht3d.org.The review was conducted separately by two reviewers. This column is presented in two parts.

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Spatiotemporal controls on septic system derived nutrients in a nearshore aquifer and their discharge to a large lake

Cited by 21 publications

References 65 publications

Occurrence of Arsenic in Nearshore Aquifers Adjacent to Large Inland Lakes

Occurrence of Arsenic in Nearshore Aquifers Adjacent to Large Inland Lakes

Evaluating lacustrine groundwater discharge to a large glacial lake using regional scale radon‐222 surveys and groundwater modelling

Artificial Sweeteners Identify Spatial Patterns of Historic Landfill Contaminated Groundwater Discharge in an Urban Stream

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