Abstract
Sediment from a wetland receiving runoff from a coal mine waste dump in the Elk River Valley of southeast British Columbia was assessed for potential selenium uptake. Selenite [SeO32-, Se(IV)] was found to adsorb to the washed sediment at pH 7 to 8, whereas no selenate [SeO42-, Se(VI)] was adsorbed, in the concentration range of 8 to 225 μg L-1 Se as selenite or selenate. Sulfate- and selenate-reducing bacterial activity was detected in the sediment. In the presence of sulfate-reducing bacteria growth medium, Se as selenate was reduced from 619(±53) μg L-1 to 15(±0.7) μg L-1, and in the presence of selenate-reducing bacteria growth medium, Se as selenate was reduced from 364(±66) mg L-1 to 22(±10) mg L-1. Semi-continuous microcosms containing sediment overlaid with selenate (500 μg L-1 Se) and sulfate (0.9 g L-1) containing water were amended with plant debris from the site or nutrients (lactate and fertilizer). Potential selenate reduction rate (0.76 h-1) was highest in the unamended microcosms. Amendment with plant debris from the site had a negative effect on selenate reduction rate in the short term (after one hour) and a positive effect on Se removal in the long term (after one week). This study suggests that wetland sediments at the mine site may be important sinks for Se.
Oligofluorene Truxene Laser Sensor: Towards Bacteria Growth Detection
