The impacts of metal and salts similar in composition to Oil sands processes affected water (OSPW) on Rainbow trout respirometry, gill structure, and gill enzyme dynamics

Abstract

Remediation of Northern Athabasca Oil sands areas has become an essential goal for engineers, biologists and industry stakeholders. Tailing ponds containing oil sand process-affected water (OSPW) have been growing in number as a byproduct of bitumen extraction activity. Treatment of OSPW can reduce some of the toxic organic components, but the inorganic constituents cannot be remediated or removed. The organic fraction of OSPW has been examined in recent years, but few studies have studied the inorganic fraction. Metals and salts (M&S) mixtures similar to OSPW were created and rainbow trout (Oncorhynchus mykiss) were exposed to these mixtures to investigate how these solutions would impact gill and swimming physiology. Medium M&S exposure caused a 25±3% decline in mean Ucrit; however, metabolic rates were primarily unaffected. An examination of gill structure and morphometrics revealed that gills were not impacted by exposure. The activities of carbonic anhydrase were similar between the control and M&S exposures, but my Cu exposure (Cu positive control) was substantially higher than the rest of the exposures. The activity of sodium potassium ATPase in fish exposed to the medium M&S mixture did not differ from control, but when compared to NaCl exposure (salt control), medium M&S exposure may have caused some ionoregulatory dysfunction. Given that treated OSPW is likely to be discharged in future, the importance of assessing the impacts of the metals and salts found in OSPW on surrounding aquatic communities should not be ignored. Future work should evaluate the implications of acute discharge of OSPW and the merits of treatment technology.