Tidal influence on BTEX biodegradation in sandy coastal aquifers

Robinson, C. E.; Brovelli, Alessandro; Barry, David Andrew; Li, Li

doi:10.1016/j.advwatres.2008.09.008

Cited by 93 publications

(84 citation statements)

References 38 publications

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“…Three different approaches have been used to compute these processes driven by oceanic forcing (Robinson et al, 2009): (i) field experiments; (ii) laboratory measurements; and (iii) numerical simulations. Austin and Masselink (2006a,b) studied hydrodynamics, morphological change and sediment transport on a gravel beach, and concluded that infiltration has important consequences for morphological changes.…”

Section: Introductionmentioning

confidence: 99%

“…Most previous investigations concerned with modeling of interactions between ocean water and coastal groundwater focused on tide-induced watertable fluctuations, neglecting high-frequency wave-induced oscillations and variable-density groundwater flow (e.g., Teo et al, 2003;Brovelli et al, 2007;Robinson et al, 2007bRobinson et al, , 2009Slooten et al, 2010;Li et al, , 2007Xin et al, 2010). However, given the interplay of mechanisms inherent in coastal processes -mixing of fresh-and seawater driven by waves, sediment transport and beach profile changes -it is not possible to extrapolate readily existing results to realistic coastal zone behavior.…”

Section: Introductionmentioning

confidence: 99%

“…The model has not been validated 8 against experimental data since no suitable data sets are available currently. On the other hand, the predictive capabilities of the each sub-module have been tested: The variabledensity groundwater flow model and the setup used to represent the cross-shore section of the aquifer were validated using experimental data collected at the field-and laboratory scales, see for example Brovelli et al (2006) and Robinson et al (2008Robinson et al ( , 2009. Validation of the nearshore hydrodynamic and sediment transport module can be found in Bakhtyar et al (2009b).…”

Section: Introductionmentioning

confidence: 99%

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Numerical experiments on interactions between wave motion and variable-density coastal aquifers

Bakhtyar

Barry

Brovelli

2012

Coastal Engineering

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A comprehensive two-dimensional (cross-shore) process-based numerical model of nearshore hydrodynamics (based on the Navier-Stokes equations, k-ε turbulence closure and the Volume-Of-Fluid method), beach morphology, and variable-density groundwater flow (SEAWAT-2000) was developed. This model, which was applied at the field scale, relaxes simplifications in existing models that do not include such detailed mechanistic descriptions. Numerical experiments were conducted to investigate the effects of varying aquifer, beach and wave characteristics (e.g., inland groundwater head, sand grain size, different wave heights and periods) on the coupled system. Spilling and plunging breakers on dissipative and intermediate beaches were simulated. For a given set of boundary conditions, the model was run for 1 y without the hydrodynamic sub-model to achieve a realistic salt-/freshwater interface. Then, the hydrodynamic component was run for 15 min and the model results analyzed. The main features considered were groundwater circulation, saltwater wedge position, in/exfiltration across the beach face, and beach morphology. The predictions of the numerical model agree well with existing understanding and experimental measurements. For an inland watertable that is lower than the still water level (SWL), such that the groundwater flow is mainly landward, on both coarse and fine sand beaches the addition of wave motion moves the saltwater wedge further landward. For an inland watertable that is higher than the SWL, the opposite behavior occurred. The numerical experiments showed that more sediment transport takes place on intermediate beaches than on dissipative beaches. In addition, beach profile variations are greater under plunging breakers, while coarse sand beaches are steeper than fine sand beaches for the same wave conditions. There is a strong correlation between in/exfiltration and beach face deposition/erosion for the coarse beaches, while in/exfiltration has a slight effect on sediment transport for fine beaches. The model is capable of simulating the short-term evolution of foreshore profile changes, and beach 3 watertable and saltwater wedge movement due to interactions between wave motion and coastal groundwater. IntroductionMost previous investigations concerned with modeling of interactions between ocean water and coastal groundwater focused on tide-induced watertable fluctuations, neglecting high-frequency wave-induced oscillations and variable-density groundwater flow (e.g., Teo et al., 2003;Brovelli et al., 2007;Robinson et al., 2007bRobinson et al., , 2009Slooten et al., 2010;Li et al., , 2007Xin et al., 2010). However, given the interplay of mechanisms inherent in coastal processes -mixing of fresh-and seawater driven by waves, sediment transport and beach profile changes -it is not possible to extrapolate readily existing results to realistic coastal zone behavior.Waves in the nearshore zone are an important forcing on sediments and groundwater behavior. While waves induce instantaneous pore wat...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Numerical experiments on interactions between wave motion and variable-density coastal aquifers

Bakhtyar

Barry

Brovelli

2012

Coastal Engineering

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“…Further, this ratio controls tide-induced recirculation rate and thus the rate of oxygen and organic matter delivery from the ocean to the STE. Even neglecting reactions, both tide and wave-induced circulations and associated saltwater-freshwater mixing can considerably reduce organic contaminant concentrations at the seabed via dilution [Robinson et al, 2007b;Robinson et al, 2009;Geng et al, 2014]. [Zhang et al, 2002;Brovelli et al, 2007;Bakhtyar et al, 2013;Liu et al, 2016].…”

Section: Organic Contaminantsmentioning

confidence: 99%

“…They demonstrated that tidal effects including tide-induced recirculation strongly influenced the distribution of the hydrocarbon compounds near the shore and their spatial and temporal discharge to the estuary. Robinson et al [2009] numerically simulated the transport of a BTEX groundwater plume in a tidally-influenced STE, considering Monod kinetics to describe the biodegradation of BTEX species. They showed that the redox gradients in the STE enhanced biodegradation of the BTEX species and subsequently reduced contaminant fluxes to the coastal ocean.…”

Section: Organic Contaminantsmentioning

confidence: 99%

Groundwater dynamics in subterranean estuaries of coastal unconfined aquifers: Controls on submarine groundwater discharge and chemical inputs to the ocean

Robinson¹,

Xin²,

Santos³

et al. 2018

Advances in Water Resources

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198

138

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Sustainable coastal resource management requires sound understanding of interactions between coastal unconfined aquifers and the ocean as these interactions influence the flux of chemicals to the coastal ocean and the availability of fresh groundwater resources. The importance of submarine groundwater discharge in delivering chemical fluxes to the coastal ocean and the critical role of the subterranean estuary (STE) in regulating these fluxes is well recognized. STEs are complex and dynamic systems exposed to various physical, hydrological, geological, and chemical conditions that act on disparate spatial and temporal scales. This paper provides a review of the effect of factors that influence flow and salt transport in STEs, evaluates current understanding on the interactions between these influences, and synthesizes understanding of drivers of nutrient, carbon, greenhouse gas, metal and organic contaminant fluxes to the ocean.Based on this review, key research needs are identified. While the effects of density and tides are well understood, episodic and longer-period forces as well as the interactions between multiple influences remain poorly understood. Many studies continue to focus on idealized nearshore aquifer systems and future work needs to consider real world complexities such as geological heterogeneities, and non-uniform and evolving alongshore and cross-shore morphology. There is also a significant need for multidisciplinary research to unravel the interactions between physical and biogeochemical processes in the STE, as most existing studies treat these processes in isolation. Better understanding of this complex and dynamic system can improve sustainable management of coastal water resources under the influence of anthropogenic pressures and climate change.

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Groundwater flow and salt transport in a subterranean estuary driven by intensified wave conditions

et al. 2014

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[1] A numerical study, based on a density-dependent variably saturated groundwater flow model, was conducted to investigate flow and salt transport in a nearshore aquifer under intensified wave conditions caused by offshore storms. Temporally varying onshore hydraulic gradients due to wave setup were determined as the seaward boundary condition for the simulated aquifer. The results showed a rapid increase in influxes across the aquiferocean interface in response to the wave event followed by a more gradual increase in effluxes. The upper saline plume first widened horizontally as the wave setup point moved landward. It then expanded vertically with recirculating seawater pushed downward by the wave-induced hydraulic gradient. The time for the salt distribution to return to the prestorm condition was up to a hundred days and correlated strongly with the time for seawater to recirculate through the aquifer. The pathways of recirculating seawater and fresh groundwater were largely modified by the wave event. These pathways crossed through the same spatial locations at similar times, indicating significant salt-freshwater mixing. The flow and salt transport dynamics were more responsive to wave events of longer duration and higher intensity, especially in more permeable aquifers with lower fresh groundwater discharge. Despite their larger response, aquifers with higher permeability and beach slope recovered more rapidly postevent. The rapid recovery of the flows compared with the salinity distribution should be considered in field data interpretation. Due to their longlasting impact, wave events may significantly influence the geochemical conditions and the fate of chemicals in a subterranean estuary.

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Tidal influence on BTEX biodegradation in sandy coastal aquifers

Cited by 93 publications

References 38 publications

Numerical experiments on interactions between wave motion and variable-density coastal aquifers

Numerical experiments on interactions between wave motion and variable-density coastal aquifers

Groundwater dynamics in subterranean estuaries of coastal unconfined aquifers: Controls on submarine groundwater discharge and chemical inputs to the ocean

Groundwater flow and salt transport in a subterranean estuary driven by intensified wave conditions

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