Twelve 1,200L mesocosms at Edith Cowan University have been filled with a 40mm layer of lake sediment from the bottom of the river fast-filled Lake Kepwari. This representative sediment layer has then been covered with Lake Kepwari water. Treatments have been allocated in a randomised two-way factorial design to test the effects of liming, phosphorus enrichment and combined liming and phosphorus amendment on different aspects of the AMD water chemistry, ecotoxicity and ecology.
The ECU team is examining water chemistry, sediment and periphyton dynamics, including the effect of liming and enhanced primary production upon dissolved heavy metal and nutrient concentrations, alkalinity and pH. Acid pit lake waters are typically low in Phosphorus due to sorption by Aluminium and Iron and liming appears to further remove this essential nutrient. Amendment by Phosphorus may required to stimulate primary productivity, in turn raising pH through nitrate assimilation and also scavenging some heavy metals.
Dr Clint McCullough
Associate Professor Mark Lund