Elevated concentrations of hydrogen sulfide produced by sulfate-reducing
prokaryotes are highly reducing, and can impair function of higher trophic levels inside end-pit lakes in the Alberta oil sands region. Microcosms have previously simulated the microbial community structure of tailing ponds; they are used here as analogues of the sediment-water interface of end-pit lake environments to determine sulfide generation patterns and the behaviour of oxygen. In this study, sulfide generation was positively correlated with depth and biotic activity, with production fluxes of ~2 x 103 nmol cm-3s-1. Oxygen consumption in the tailings is dependent on both biotic and abiotic processes. These results have implications for quantitatively estimating impacts of sulfide production and oxygen availability to biota, in addition to the biogeochemical cycles linked to their functional roles in tailings-affected ecosystems.