Amanda Charles

Mechanistic uptake of uranium in freshwater macrophytes


Amanda Charles A key recommendation from the Australian water quality guidelines for the protection of aquatic ecosystems (ANZECC and ARMCANZ, 2000) is the requirement for more data on the toxicity and bioavailability of uranium to local organisms, particularly plants. Further, more knowledge is required on the effects of varying water chemistry variables, such as pH or water hardness on metal toxicity. These issues will be addressed as one component of Charlie’s PhD project. These issues are important to derive data suitable for more reliable ecological risk assessments of contaminated environments. This issue is being driven by several state and Federal government departments (e.g. Environment Australia, Environment Protection Authorities). Tropical Australia (40% of the continent) has a large number of mining operations, many located in pristine freshwater catchments (e.g. Ranger/Jabiluka uranium mines). As part of the water management strategies at the mines, waste waters, containing elevated metal levels, may be released into local streams during the wet season (i.e monsoonal climate). This may lead to the contamination of the receiving freshwater ecosystems. One of the more important components of the local freshwater ecosystems are submerged rooted macrophytes, providing structure, substrate, habitat, sediment stability, biomass to support this ecosystem. Submerged rooted macrophytes are also an important component of artificial wetlands, which are constructed at mine sites, such as Ranger, to “filter” contaminants prior to discharge to receiving waters. However, little is known of the uptake kinetics and distribution of metals once incorporated into the plant tissue. Furthermore, is water or sediment the major metal source?