Model describing the rates of transfer processes of organic chemicals between atmosphere and water

Mackay, D.; Paterson, Sally; Schroeder, W. H.

doi:10.1021/es00150a009

Cited by 195 publications

(121 citation statements)

References 14 publications

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“…The mean annual net flux (F net ) was estimated using the following equation: where ⌺F is the net mass exchanged with units of mass yr Ϫ1 , K ol is the overall mass transfer coefficient (m day Ϫ1 ), C w is the concentration of the contaminant in the dissolved phase (mass l Ϫ1 ) in the surface water of the lake, C a is the vapor phase concentration of the contaminant in the atmosphere (mass m Ϫ3 ), R is the universal gas constant (8.21 ϫ 10 -5 m 3 atm K Ϫ1 mol Ϫ1 ), T is the surface water temperature (K) and H is the Henry's Law constant (atm m 3 mol Ϫ1 ). This equation predicts that the gas flux across the lake surface is a balance between volatilization from and absorption to the water surface, and is controlled by Henry's Law, the concentration gradient, and the overall mass transfer velocity (Liss and Slater 1974;Mackay and Yeun 1983). A correct assessment of H as a function of temperature is needed to determine the direction and magnitude of compound flux across the airwater interface.…”

Section: Model Development and Calculationsmentioning

confidence: 99%

“…Upon entry into the aquatic environment they rapidly associate with suspended particulate material and sediments. Their ultimate fate is dictated by a variety of physical, chemical, and biological interactions, including partitioning between water and particles in the water column, hydraulic transport out of the lake, volatilization, uptake by biota, photolytic and biological degradation, sedimentation and recycling within the water column and between bottom sediments and water column (Baker et al 1985;Mackay et al 1986;Swackhamer et al 1988;Jeremiason et al 1994;Pearson et al 1996).…”

mentioning

confidence: 99%

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Towards a complete mass balance and model for PCBs and PAHs in a small rural lake, Cumbria U.K.

Gevao

Hamilton−Taylor

Jones

2000

Limnology & Oceanography

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This paper summarizes the processes of exchange/fluxes for polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in a small well-studied rural lake, Esthwaite Water in northwest England. Measurements of PCB and PAH concentrations have been made in rain, air, water, dated sediment cores, and sediment trap samples over a 2-yr study period and used to determine fluxes to and from the lake. A steady state mass balance model was used to construct an input-output budget for the chemicals and to investigate the relative importance of transport into and out of the lake. The hydraulic transport from the lake was the most important loss mechanism for both PCBs and PAHs. Volatilization, not sedimentation, is currently the dominant loss process for PCBs in the water column, whereas, sedimentation exceeds volatilization for PAHs. The data further suggest that the current sediment-water flux is upward for PCBs and downwards for PAHs, indicating that the sediments might be acting as a secondary source for PCBs but continue to act as a sink for PAHs. Riverine, catchment runoff, or both are believed to be the most important input for PCBs and PAHs to the lake although direct aerial deposition to the lake is also important for PCBs. Differences in the mixtures of compounds in the various compartments suggests significant fractionation of PCBs and PAHs in the air-water-sediment system in the lake.

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Section: Model Development and Calculationsmentioning

confidence: 99%

mentioning

confidence: 99%

Towards a complete mass balance and model for PCBs and PAHs in a small rural lake, Cumbria U.K.

Gevao

Hamilton−Taylor

Jones

2000

Limnology & Oceanography

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“…The aquifer and catchment sub-models are capacity models consisting of cells with a limited number of variations in parameter properties, parameterised on English aquifers and river water catchments. Every time step, substance degradation, inflow and outflow are calculated, after which a new equilibrium is obtained (MacKay et al, 1986). The surface water predictions by VetPec have been validated with a selection of monitoring data on the pesticide isoproturon.…”

Section: Functional Validation For Surface Watermentioning

confidence: 99%

Validation of the exposure assessment for veterinary medicinal products

Montforts

2006

Science of The Total Environment

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Under the EU Directive 2004/28/EC, an environmental risk assessment of new veterinary medicinal products is required. Given the nature of risk assessment for new applications, there is a need to model exposure concentrations. Critical evaluations are essential to ensure that the use of models by regulators does not result in the propagation of misleading information. The empirical validations of soil exposure models, previously discussed in this journal, indicate that it is impossible to analyse the contribution of every model parameter to the variability in the predictions. In particular, the prediction of the slurry concentration is challenged by uncertainties concerning dilution, mixing and dissipation of residues. Surface water and groundwater models generated highly deviating results compared to the field results, questioning the usefulness of the available screening models. Animal husbandry, slurry handling and environmental conditions throughout Europe are considered in order to define realistic worst case scenarios, to be used in conjunction with distribution models for the environmental risk assessment of veterinary medicinal products at registration. Given the variability in manure management practice throughout Europe, a deterministic approach for the manure-to-soil model was selected. Both worst case and best case scenario were developed. Several modelling assumptions applied in the surface water exposure model for fish nursery effluent were validated against newly available data. Since the available data give no proof that a settling tank contributes to the removal of pesticides from waste water, it is recommended for risk assessment purposes to consider the contribution of the settling tank to removal of pesticides and medicines to be negligible. Surface water dilution factors may be considered to be rather small, a factor of 2, for low flow situations.

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“…In a simplified case, the following equation is most commonly used to calculate particulate fluxes (Mackay, 1986). C p = conc.…”

Section: Particle Dry Depositionmentioning

confidence: 99%

“…The flux of contaminmlt wet deposition from the atmosphere to surface water by rain and snow can be determined from the equation (Mackay, 1986 …”

Section: Wet Deposition Of Vapor and Particlementioning

confidence: 99%

Modeling the Water Column, Sediment and Biota Concentrations of The Detroit River

Lin

Kummler

1995

JWMM

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Model describing the rates of transfer processes of organic chemicals between atmosphere and water

Cited by 195 publications

References 14 publications

Towards a complete mass balance and model for PCBs and PAHs in a small rural lake, Cumbria U.K.

Towards a complete mass balance and model for PCBs and PAHs in a small rural lake, Cumbria U.K.

Validation of the exposure assessment for veterinary medicinal products

Modeling the Water Column, Sediment and Biota Concentrations of The Detroit River

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