Risks of hypoxia and acidification in the high energy coastal environment near Victoria, Canada's untreated municipal sewage outfalls
Wastewater disposal often has deleterious impacts on the receiving environment. Low dissolved oxygen levels are particularly concerning. Here, we investigate the impacts on dissolved oxygen and carbon chemistry of screened municipal wastewater in the marine waters off Victoria, Canada. We analyzed d...
| Published in: | Marine Pollution Bulletin |
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| Main Authors: | , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Marine Pollution Bulletin
2018
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| Subjects: | |
| Online Access: | https://doi.org/10.1016/j.marpolbul.2018.05.018 https://dspace.library.uvic.ca//handle/1828/10223 |
| Summary: | Wastewater disposal often has deleterious impacts on the receiving environment. Low dissolved oxygen levels are particularly concerning. Here, we investigate the impacts on dissolved oxygen and carbon chemistry of screened municipal wastewater in the marine waters off Victoria, Canada. We analyzed data from undersea moorings, ship-based monitoring, and remotely-operated vehicle video. We used these observations to construct a two-layer model of the nearfield receiving environment. Despite the lack of advanced treatment, dissolved oxygen levels near the outfalls were well above a 62 μmol kg−1 hypoxic threshold. Furthermore, the impact on water column oxygen at the outfall is likely <2 μmol kg−1. Dissolved inorganic carbon is not elevated and pH not depressed compared to the surrounding region. Strong tidal currents and cold, well-ventilated waters give Victoria's marine environment a high assimilative capacity for organic waste. However, declining oxygen levels offshore put water near the outfall at risk of future hypoxia. We thank Marty Davelaar for the analysis of our carbon samples, Shirley Lyons for providing field support and sharing past data collected by the CRD, Ken Denman and Sophia Johannessen for their helpful comments on the manuscript, Ocean Networks Canada for data support as well as the captain and crew of the MSV John Strickland. Funding was provided by a NSERC Industrial Postgraduate Scholarship (#477944) to J. Krogh, the Capital Regional District Environmental Protection Division, Debby Ianson was supported by Fisheries and Oceans Canada. None of the funding sources influenced the study design, data analysis, data interpretation, or the decision to publish. The Capital Regional District was involved in sample collection near outfalls owned by them. Faculty Reviewed |
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