Relative role of pore water versus ingested sediment in bioavailability of organic contaminants in marine sediments

Abstract

Abstract-Experimental data for fluoranthene and feeding selectivity in combination with reaction-diffusion modeling suggest that ingestion of contaminated sediment may often be the dominant uptake pathway for deposit-feeding invertebrates in sediments. A dietary absorption efficiency of 56% and accompanying forage ratio of 2.4 were measured using natural sediment that had been dual-labeled ( 14 C: 51 Cr) with fluoranthene and fed to the marine deposit-feeding polychaete Capitella species I. Only 3 to 4% of the total absorption could be accounted for by desorption during gut passage. These data were then used as input into a reactiondiffusion model to calculate the importance of uptake from ingested sediment relative to pore-water exposure. The calculations predict a fluoranthene dietary uptake flux that is 20 to 30 times greater than that due to pore water. Factors that act to modify or control the formation of local chemical gradients, boundary layers, or dietary absorption rates including particle selection or burrow construction will be important in determining the relative importance of potential exposure pathways. From a chemical perspective, the kinetics of the adsorption and desorption process are especially important as they will strongly influence the boundary layer immediately surrounding burrowing animals or irrigated tubes. The most important biological factors likely include irrigation behavior and burrow density and size.

Levels and Origin of PAHs in Some Big Lakes

“…It is well known that of organic pollutants, related to these kinds of industry, the phenols, chlorinated hydrocarbons (dioxin), and polycyclic aromatic hydrocarbons (PAHs) are more specific and hazardous (1)(2)(3)(4)(5)(6)(7). PAHs are of concern because they have been found to be carcinogenic, mutagenic, and they bioaccumulate in organisms (8)(9)(10)(11)(12). However, the information about the levels of PAHs in Lake Baikal as well as sources of contamination is limited.…”

Quantification and characterization of dissolved organic carbon and iron in sedimentary porewater from Green Bay, WI, USA

“…Dissolved organic carbon (DOC) in sedimentary porewater plays a significant role in many biogeochemical processes in aquatic environments, including the flux of sedimentary organic carbon to the overlying water (Alperin et al 1999;Burdige et al 1999); the remineralization and preservation of organic matter (Alperin et al 1994;Hedges and Keil 1995;Burdige et al 1999); and the distribution (Brownawell and Farrington 1986;Capel and Eisenreich 1990;Chin and Gschwend 1992;Mitra and Dickhut 1999), mobility (Thoma et al 1991;Valsaraj and Sojitra 1997;Skrabal et al 2000), and bioavailability (Harkey et al 1994;Forbes et al 1998) of contaminants. The porewater DOC pool is composed of an array of organic compounds that are often operationally grouped on the basis of their molecular weights.…”

Testing and Risk Assessment of Persistent and Bioaccumulating Chemical Substances—Improvements within REACH?

“…One plausible way of solving this problem may be to relate effect levels to particulate material, sediment, prey and so on (e .g., Chandler and Green 2001) instead of the test medium, which in fact may not be the major or at least not the single route of exposure for many difficult substances (Forbes et al 1998;Breitholtz and Wollenberger 2003). To be able to accurately predict the environmental risk of chemicals, this will in addition demand increased understanding of fate and exposure pathways of these difficult substances in various test systems.…”