Selenium in sediments, pore waters and benthic infauna of Lake Macquarie, New South Wales, Australia

Measurements of selenium in sediments and benthic infauna of Lake Macquarie , an estuary on the east coast of Australia, indicate that sediments are a significant source of selenium in the lake's food web. Analysis of surficia l sediment samples indicated higher selenium concentrations near what are b elieved to be the main industrial sources of selenium to the lake: a smelte r and a power station. Sediment cores taken from sediments in Mannering Bay , near a power station at Vales Point, contained an average of 12 times mor e selenium in surficial sections than sediment cores from Nord's Wharf, a p art of the lake remote from direct inputs of selenium. The highest selenium concentration found in Mannering Bay sediments (17.2 mu g/g) was 69 times the apparent background concentration at Nord's Wharf (0.25 mu g/g). Pore w ater concentrations in Mannering Bay were also high, up to 5 mu g/l compare d to those at Nord's Wharf which were below detection limits (0.2 mu g/l). Selenium concentrations in muscle tissues of three benthic-feeding fish spe cies (Mugil cephalus, Platycephalus fuscus, Acanthopagrus australis) were s ignificantly correlated (p < 0.05) with surficial sediment selenium concent ration. Selenium concentrations in polychaetes and molluscs of Mannering Ba y were up to 58 times higher than those from Nord's Wharf. Two benthic orga nisms, the eunicid polychaete Marphysa sanguinea and the bivalve mollusc Sp isula trigonella, were maintained at different densities in selenium-spiked sediments. Both animals accumulated selenium from the spiked sediment, con firming that bioaccumulation from contaminated sediments occurs. Collective ly, these data suggest that benthic food webs are important sources of sele nium to the fish of Lake Macquarie. (C) 1999 Elsevier Science Ltd. All righ ts reserved.