Bioaccessibility of Zinc in Estuarine Sediment Contaminated by Tire Wear Particles

The bioaccessibility of Zn in tire wear particles (TWP) has been studied in incubations in the presence of estuarine sediment and solutions that mimic the digestive chemistry of sediment-ingesting invertebrates. Sea water solutions of the protein bovine serum albumin (BSA), a surrogate for digestive amino acids, released about 2?% of total Zn from sediment?CTWP preparations (in ratios of 100:1, 12:1 and 6:1) after a 5-h period. Although sodium taurocholate, a surrogate of digestive surfactancy, released quantities of Zn that were not always greater than those released by a sea water control, addition of taurocholate to BSA in sea water enhanced Zn release by solutions of the protein alone. Time courses of Zn release by BSA, with or without taurocholate, conformed to a diffusion-controlled reaction, with rate constants ranging from about 0.1 to 2?mg?L^?1?h^?1/2. Results of the study suggest that sediment-ingesting invertebrates inhabiting coastal environments impacted by urban runoff are instrumental to the mobilisation of Zn.