Bioaccessibility and bioavailability of Cu and Zn in sediment contaminated by antifouling paint residues.

The bioaccessibility and bioavailability of the principal metallic constituents of spent antifouling particles ([Cu] = 300 mg g(-1); [Zn] = 100 mg g(-1)) have been evaluated by in vitro incubations and in microcosms containing the marine deposit-feeder Arenicola marina. In mixtures of sediment and paint, metal accessibility to the protein, bovine serum albumin, a surrogate for the gutfluids of deposit feeders, increased as the proportion of paint particles in the sample decreased. This effect was attributed to solubility constraints on metal salts and complexes and resulted in estimates of bioaccessibility in paint residues ranging from about 0.3% to 1.7% for Cu and 0.2% and 2.3% for Zn. A. marina maintained in sediment-paint cores and in paint leachate accumulated Cu with accumulation factors of about 0.1% and 0.5%, respectively, suggesting that both diet and aqueous exposure contribute to the uptake of this metal. In contrast, Zn was not measurably accumulated by either exposure route, suggesting that A. marina is able to regulate this metal. Through burial and conveyor-belt feeding, A. marina also accelerated both the subduction of antifouling residues and the mobilization of metals into the interstitial and overlying waters. The findings of this study have important implications regarding the cycling of trace metals in coastal waters impacted by boating activities.