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Water and Fine-grained Sediment Assessment in the Capital Region (Edmonton) of the North Saskatchewan River (Canada)
- Author / Creator
- Jin, Rong
Purpose: To better understand the behaviors of sediment-associated metals (Cu, Ni, Cd, Mn, Cr, Pb, Fe, Sr, Mo, and Co), an evaluation of physicochemical parameters and metal speciation on suspended and bedload sediment collected from the North Saskatchewan River was conducted in 2018. Sampling sites were selected within the urban region (Edmonton) to assess the influences of anthropogenic inputs (e.g., municipal waste and/or agrochemical runoff) on water and sediment qualities.
Methods: The sequential extraction procedure was modified based on Tessier’s method to investigate the association of metals with different fractions of sediments (e.g., exchangeable, carbonate, Fe-Mn oxides, organics, and residual fractions). The mineralogical composition and particle size distribution (<63μm) were measured to help interpret the metal fractionation patterns. Pollution levels were assessed by comparing results with the fresh water and sediment quality guidelines (WQGs and SQGs) published by Environment Canada. Risk assessment code (RAC) was employed to evaluate the bioavailability and potential toxicity of heavy metals.
Results: Generally, suspended sediment contains more clay minerals, carbonates and particulate organic carbon than bedload sediment. The size fractionation data indicate that there were more clay-sized particles (<2μm) in suspended sediment. Sr, Cd, and Mo represented appreciable portions in exchangeable fraction. Substantial amounts of Cu, Sr, Cd, Mn, Co, and Pb were associated with carbonate fraction and Co, Pb, Ni, Fe, and Cr were predominantly bound to Fe- Mn oxides and residual fraction. Cu and Mo represented relatively high proportions in oxidizable fraction. For most heavy metals except for Cu and Mo, larger parts of non-residual fractions can be observed in suspended sediments than in bedload sediments. Water quality assessment reveals that all dissolved toxic metals and nutrients were in the environmentally acceptable ranges posted by WQGs. SQGs suggest that the total concentrations of Mn, Ni and Cr in all sediment samples, Cu in bedload samples and Cd in suspended samples were of environmental concern in the present study and can occasionally be associated with adverse biological effects. According to RAC, for both suspended and bedload sediments, Cr, Fe showed low risk, Co and Pb showed medium risk and Mn showed very high risk to the environment. Other metals such as Ni, Mo, Cu, Sr and Cd showed different levels of toxicity to the environment at different sampling sites.
Conclusion: This study provides information about the sources, storage patterns (in suspended and bedload sediment), fate and environmental impacts (bioavailability and potential toxicity) of metals in the NSR and helps monitor the anthropogenic influences caused by a large city (Edmonton) to better characterize the contaminant chemistry of the river.
- Subjects / Keywords
- Graduation date
- Fall 2022
- Type of Item
- Master of Science
- This thesis is made available by the University of Alberta Library with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.