S reactivity of an oil sands composite tailings deposit undergoing reclamation wetland construction.

摘要: This study is the first to characterize S stability of a composite tailings (CT) deposit undergoing pilot wetland reclamation in Athabasca Oil Sands Region (AOSR, Alberta, Canada). As CT sulfur, organic carbon and bacterially rich, goal this was situ aqueous distribution sulfur compounds across wetland, sand cap underlying zones deposit, an effort establish potential for microbial cycling generation H2S, explosive, corrosive toxicity risk. Porewater samples from three depths spanning different layers as well surface ponded water were collected geochemical analyses (July Sept 2013), enrichments (both reducing oxidizing bacteria) June 2014. While porewater ΣH2S(aq) detected at all results identify that layer required construction, acts mixing zone generating highest solution H2S concentrations (>500 uM or 18 mg/L) gas levels (over 100 up 180 ppm) observed. dissolved sulfate (0.14-6.97 mM) orders magnitude higher did not correlate observed ΣH2S throughout deposit. Unique sandcap, positively correlated with maxima seen layer. The management critical factor trends. Active dewatering resulted migration rich into while downwelling labile developing acted concert stimulate structural Functional identified diverse metabolisms are widespread indicating these waste materials biogeochemically reactive implications longterm stability. These relevance both oil sands region, other mine contexts where wastes occur, identifying need consider driven C constituents concern, such deposits minimize