Novel Passive Sampling Device for Measuring Sediment–Water Diffusion Fluxes of Hydrophobic Organic Chemicals

Abstract

Molecular diffusion across the sediment−water interface, as one of the key geochemical processes, dictates whether a sediment is a source or sink of chemicals, providing useful data in designing remedial actions. Despite ample previous efforts in quantifying sediment−water diffusion fluxes, the resulting methods are largely unsatisfactory. Herein, we introduce a novel passive sampling device capable of measuring vertical profiles of chemical concentrations near the sediment−water interface, from which diffusion fluxes can be calculated based on a model that we developed. In laboratory testing, diffusion fluxes (0.032−310 ng m −2 d −1 ) of dichlorodiphenyltrichloroethane and its metabolites obtained from the present sampling device were consistent with those (0.38− 610 ng m −2 d −1 ) determined by using a conventional active sampling method, solid-phase extraction/liquid−liquid extraction. Field deployment of the sampling device yielded individual diffusion fluxes of p,p′-DDD, p,p′-DDE, p,p′-DDMU, o,p′-DDMU, p,p′-DDNU, and p,p′-DBP in the range of 5.9−150 ng m −2 d −1 , which were comparable to those (5.5−85 ng m −2 d −1 ) obtained with a benthic chamber. Moreover, diffusion fluxes of p,p′-DDT and o,p′-DDT obtained with the sampling device were negative; i.e., the sediment is acting as a sink for these chemicals, while that could not be found using the benthic chamber. Thus, the passive sampling device can provide better information about the movement of chemicals through the sediment and overlying water for the choice of remedial strategies.

Recent advances in the field measurement of the diffusion flux of hydrophobic organic chemicals at the sediment-water interface

“…The model-calculated fluxes were consistent with those acquired by solid-phase extraction/liquid-liquid extraction and a benthic chamber [49], suggesting that the sampling device is a powerful tool for measuring fluxes of HOCs across the sediment-water interface.…”

“…1c and Table 1), from which the magnitude and the direction of sediment-water diffusion fluxes can be determined using a mathematical model that we developed ourselves [49]. This sampling device employs LDPE as the sorbent phase, and glass-fiber filtration (GF/F) membranes and porous stainless-steel shields as the protective mechanism (Fig.…”

“…With LDPE as the sorbent phase, our previous studies [49,57] demonstrated that LDPE is an ideal sorbent (i.e. uptake of a chemical by LDPE is so rapid that the chemical concentration can be maintained at nearly 0 at the sorbent surface).…”

Source apportionment of DDTs in maricultured fish: a modeling study in South China

“…Hailing Bay and Daya Bay of Guangdong Province, China (Fig. 1) were selected as the study sites, as they have been under intensive investigation for a number of years (Guo et al 2009b;Liu et al 2013;Yu et al 2011a). The results derived from the current modeling efforts were expected to offer in-depth insights into the exposure paths and mechanisms for organic contaminants to enter maricultured fish and ultimately accumulate in humans via fish consumption.…”

Modeling the fate of p,p′-DDT in water and sediment of two typical estuarine bays in South China: Importance of fishing vessels' inputs

“…Our previous studies have accumulated abundant data in two estuarine bays, i.e., Daya Bay and Hailing Bay (Fig. 1), of South China (Fang et al, 2016;Guo et al, 2009;Liu et al, 2013;Yu et al, 2011a,b), which presented the possibility to evaluate the impacts of DDT released from antifouling paints with a comprehensive modeling study. Because of its dominance among all DDT components (including o,p 0 -and p,p 0 -DDT, DDE, and DDD) in antifouling paints, p,p 0 -DDT was selected as the target compound.…”