Sulfate reducing bacterial community and in situ activity in mature fine tailings analyzed by real time qPCR and microsensor

Abiotic and biotic constituents of oil sands process-affected waters

The oil sands in Northern Alberta are the largest oil sands in the world, providing an important economic resource for the Canadian energy industry. The extraction of petroleum in the oil sands begins with the addition of hot water to the bituminous sediment, generating oil sands process-affected water (OSPW), which is acutely toxic to organisms. Trillions of litres of OSPW are stored on oil sands mining leased sites in man-made reservoirs called tailings ponds. As the volume of OSPW increases, concerns arise regarding the reclamation and eventual release of this water back into the environment. OSPW is composed of a complex and heterogeneous mix of components that vary based on factors such as company extraction techniques, age of the water, location, and bitumen ore quality. Therefore, the effective remediation of OSPW requires the consideration of abiotic and biotic constituents within it to understand short and long term effects of treatments used. This review summarizes selected chemicals and organisms in these waters and their interactions to provide a holistic perspective on the physiochemical and microbial dynamics underpinning OSPW .

Chloramine Disinfection-Induced Nitrification Activities and Their Potential Public Health Risk Indications within Deposits of a Drinking Water Supply System

Microsensors were applied to study the diffusion reaction and activity of a nitrogen species of deposit sediment from a drinking water supply system. Microprofiles of dissolved oxygen (DO), NH₄⁺-N, NO₃^--N, and NO₂^-N in the sediment indicated that the DO concentration decreased from the highest at the sediment surface to zero at the bottom of the sediment. Similarly, with the increase of depth, NH₄⁺-N initially increased rapidly and then decreased slowly, while the concentration of NO₃^--N reached a maximum at around 6000 μm and then decreased to about 0.1 mg·L^-1 near the bottom of the sediment. Almost no change was observed for NO₂^--N. The decrease of NH₄⁺-N and DO corresponded well with the increase of NO₃^--N. Furthermore, based on a consumption and production rate analysis, DO has always been consumed; the NH₄⁺-N consumption rate increased rapidly within 0-1000 μm, reaching about 14 mg·L^-1·S^-1·10^-9. A small amount of NH₄⁺-N was produced in 2000-6000 μm, which could be attributed to denitrification activity. There was no change deeper than 6000 μm, while NO₃^--N was produced at a depth between 0 and 6000 μm and was consumed in the deeper zone. At the depth of 9000 μm, the NO₃^--N consumption reached a maximum of 5 mg·L^-1·S^-1·10^-9. The consumption of DO and NH₄⁺-N, which corresponded with the production of NO₃^--N in a specific microscale range within the sediment, demonstrated nitrification and denitrification activities. In addition, the time required for the diffusion of only DO, NH₄⁺-N, NO₃^--N, and NO₂^--N was estimated as 14 days; however, in the practical, even after 60 days of operation, there was still a continuous reaction, which provided further evidence towards microbial activities within the sediment.