John Wiley & Sons, Ltd.

Modeling the transport of organic chemicals between polyethylene passive samplers and water in finite and infinite bath conditions

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Understanding the transfer of chemicals between passive samplers (PS) and water is essential for their use as monitoring devices of organic contaminants in surface waters. By applying Fick's 2nd law to diffusion through the polymer and an aqueous boundary layer, we derived a mathematical model for the uptake of chemicals into PS from water, in finite and infinite bath conditions. The finite bath model performed well when applied to laboratory observations of sorption into polyethylene (PE) sheets for various chemicals (PAHs, PCBs and DDTs) and at varying turbulence levels. We used the infinite bath model to infer fractional equilibration of PCB and DDT analytes in field‐deployed PE, and the results were nearly identical to those obtained using the sampling rate model. But further comparison of our model and the sampling rate model revealed that the exchange of chemicals was inconsistent with the sampling rate model for partially or fully membrane‐controlled transfer, which would be expected in turbulent conditions or when targeting compounds with small polymer diffusivities and small partition coefficients (e.g., phenols, some pesticides and others). The model can be applied to other polymers besides PE, as well as other chemicals, and in any transfer regime (membrane, mixed or water‐boundary‐layer controlled). Lastly, we illustrate practical applications of this model such as improving PS design and understanding the kinetics of passive dosing experiments. This article is protected by copyright. All rights reserved

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