Selenium cycling in a marine dominated estuary: Lake Macquarie, NSW, Australia a case study

Environmental context Knowledge of the fate selenium in estuaries receiving inputs from coal-fired power stations is essential as these environments are important nursery habitats for marine life and has been shown to cause fish bird mortality sublethal effects including oedema, chromosomal aberrations reproductive success. Understanding cycling allows risk assessment be undertaken appropriate action protect resident organisms. Abstract The (Se) station operations a dominated estuary, Lake Macquarie NSW, explored, well Se toxicity, population effects. Selenium rapidly adsorbed sediments, food webs based on benthic sources. remobilised sediments by volatilisation diffusional processes following bioturbation. It then transferred into chains via microalgae, deposit feeders filter-feeding organisms processing suspended sediments. Historically, found accumulate levels above those considered safe human consumption. After remediation major ash dam 1995, have declined, concentrations also reduced partially due deposition cleaner sediment but formation volatile dimethyl selenide. Bioturbation oxidised surface results release inorganic Se. In response decreases concentrations, molluscs below deleterious levels, with most now being involves transformation species (Se0, SeII, SeIV, SeVI) water column dimethylselenide diselenide bacteria accumulation organic plant detritus (selenomethionine) animals (selenomethionine selenocysteine). Dissolved Macquarie, except near inputs, always that toxicity. There evidence sediment-spiking studies, however, probably causing When undertaking assessments Se, careful consideration should given understanding remobilisation not all systems act accordance published studies generally high phytoplankton-based webs.