International Mine Water Association
Faculty of Computing, Health and Science
School of Natural Sciences / Centre for Ecosystem Management
Acidic pit lakes often have elevated metal concentrations, very low nutrient concentrations and very low algal primary productivity. A microcosm experiment was performed to identify the main limiting factor(s) for algal biomass. Nutrients (N, P and C) were added in all possible combinations to pit lake water in the presence or absence of pit lake sediment. Microcosms without sediment showed higher chlorophyll a concentrations compared to the treatments with sediment. Microcosms where nitrogen and phosphorus were added showed highest chlorophyll a concentrations. Results suggest that algal biomass in pit lakes may be primarily limited by low nitrogen and phosphorus concentrations.