The importance of hardness and alkalinity in assessing the potential impact of heavy metals on tropical freshwater organisms

Environment Australia, 1999

Internal Report 322
Reithmuller N, Markich S, van Dam R & Parry D
Supervising Scientist Division

About the report

The Australian and New Zealand water quality guidelines are aiming to supplement and modify existing criteria, which are mostly based on Northern Hemisphere toxicity data, with information relevant to the Southern Hemisphere as it becomes available. In the wet-dry tropics of Australia, uranium (U) and copper (Cu) are metals of particular concern, due to mining activities. Although, the toxicity of U and Cu to tropical freshwater species has previously been characterised, the influence of physico-chemical paramenters on toxicity has not been defined. In contrast, temperate freshwater studies have investigated the effects of various physico-chemical parameters on Cu toxicity, and to a limited extent U toxicity. The reported results however, are contradictory. Thus, it is recognised that the development of a model based on key water quality variables would enhance the capacity to predict the potential site-specific impacts of U and Cu in tropical ecosystems.