Environmental conditions controlling selenium volatilization from a wetland system

Natural selenium volatilization from Benton Lake, MT, a wetland system containing moderate levels of selenium, was studied in water-sediment, water-sediment with a flooding-drying cycle, and plant-water-sediment microcosms. Results showed that selenium volatilization occurred from water, sediment, and wetland plants. Sediment and plants were the major producers of volatile selenium from the system. The rate of selenium volatilization from algae and high-selenium sediment was much higher than that from watermilfoil and low-selenium sediment. The rate was also controlled by various environmental factors. Higher temperature, higher air flow, flooding-drying and the decomposition of wetland plants greatly increased the removal rates of selenium through selenium volatilization. Our results suggest that natural selenium volatilization can be an important process removing selenium from wetland systems.