Iron-sulfide and trace element behaviour in sediments of Coombabah Lake, southern Moreton Bay (Australia)

摘要

Iron-sulfide minerals in benthic sediments may sequester potentially toxic trace elements that are introduced to estuaries from natural and anthropogenic sources (Chapman et al., 1998; Morse and Luther, 1999; Simpson et al., 2002; Teasdale et al., 2003). Understanding iron-sulfide formation in benthic sediments is therefore central to assessing the risk posed by sedimentary trace elements (Machado et al., 2004; Burton et al., 2005a, 2006a). This report provides a baseline description of sedimentary iron-sulfide and trace element behaviour in Coombabah Lake - a sub-tropical estuarine lake in southern Moreton Bay, Australia (Fig. 1). Moreton Bay is located in one of Australia's fastest growing urban regions with a population of over 3 million (ABS, 2002). Urban development within the Coombabah Lake catchment may increase contaminant inputs from a range of sources, including urban stormwater runoff and acid-sulfate soils. For this reason, recent work has aimed at establishing baseline conditions in Coombabah Lake and other areas within Moreton Bay (Burton et al., 2004, 2005a; Dunn et al., 2007). Coombabah Lake is shallow (< 1 m water depth at low tide) and turbid, due to tide- and wind-induced sediment resuspension. Salinity in Coombabah Lake spans 25 psu-35 psu over a tidal cycle, with lower salinity conditions occurring during infrequent freshwater inputs from Coombabah Creek (Fig. 1).