Results and Discussion
Spatial and Seasonal Variations in Water Quality Parameters Concentrations |
Table 3. Comparison of mean concentrations for selected parameters at the stations downstream and upstream the City of Edmonton. SD = standard deviation; t Statistic = statistical estimate of the magnitude of difference between stations; p-value = probability value. Highlighted cells in the table help to emphasize specific findings. Yellow highlighted cells represent non-significant results (p > 0.05) from the t-tests, while blue highlighted cells indicate significant differences (p < 0.05) between the upstream and downstream stations for a given parameter and season.
Total phosphorus concentrations were significantly lower at the upstream station (0.005 mg/L) compared to the downstream station (0.013 mg/L; p < 0.05) during the winter months. However, this difference was not observed in the summer season. Total dissolved solids exhibited higher concentrations downstream of Edmonton during both summer and winter, with mean values of 204.242 mg/L and 226.222 mg/L, respectively. Upstream at Pakan Bridge, mean concentrations were 185.758 mg/L in winter and 199.546 mg/L in summer.
Total nitrate plus nitrite concentrations were significantly lower at the upstream station during the summer (0.038 mg/L) compared to the downstream station (0.284 mg/L; p < 0.05). This pattern was also observed during the winter, with mean upstream concentrations of 0.06 mg/L and downstream concentrations of 0.368 mg/L (p < 0.05). E.coli concentrations were notably lower at the upstream station (178 No/100 mL) compared to the downstream station (1855.571 No/100 mL; p < 0.05) during the summer, while no significant differences were detected during the winter season.
For parameters such as pH, dissolved oxygen, total mercury, and total organic carbon, no significant differences were observed between the upstream and downstream stations.
Total nitrate plus nitrite concentrations were significantly lower at the upstream station during the summer (0.038 mg/L) compared to the downstream station (0.284 mg/L; p < 0.05). This pattern was also observed during the winter, with mean upstream concentrations of 0.06 mg/L and downstream concentrations of 0.368 mg/L (p < 0.05). E.coli concentrations were notably lower at the upstream station (178 No/100 mL) compared to the downstream station (1855.571 No/100 mL; p < 0.05) during the summer, while no significant differences were detected during the winter season.
For parameters such as pH, dissolved oxygen, total mercury, and total organic carbon, no significant differences were observed between the upstream and downstream stations.
Conclusions
Spatial variations
The presence of significant differences in some parameters, such as total phosphorus, total dissolved solids, total nitrate plus nitrite, and E.coli, indicates that there are spatial variations in water quality along the North Saskatchewan River. These variations could be attributed to various factors, including urbanization, industrial discharges, agricultural runoff, and wastewater treatment plant effluents in the Edmonton area. In this case, the implementation of targeted management measures is recommended to reduce the impact of these sources on water quality, such as upgrading wastewater treatment plants, enforcing industrial effluent standards, and promoting best management practices in agriculture.
Seasonal variations
Some of the parameters exhibited seasonal variations. For instance, significant differences in total phosphorus and E.coli concentrations between upstream and downstream stations were observed during the winter but not during the summer season. These seasonal patterns might be related to changes in precipitation, temperature, and land use practices throughout the year, which can influence water quality dynamics. In this cases, it is recommended to implement adaptive management strategies that address seasonal changes in water quality, such as increasing monitoring frequency during high-risk periods, regulating land-use practices to minimize nutrient and sediment runoff, and promoting the use of green infrastructure to reduce urban stormwater pollution.
Consistent parameters
Some water quality parameters, such as pH, dissolved oxygen, total mercury, and total organic carbon, did not show any significant differences between upstream and downstream stations, suggesting that these parameters might be less influenced by the local factors affecting the river. This could indicate that the water quality in terms of these parameters is relatively consistent along the North Saskatchewan River in the studied area.
The presence of significant differences in some parameters, such as total phosphorus, total dissolved solids, total nitrate plus nitrite, and E.coli, indicates that there are spatial variations in water quality along the North Saskatchewan River. These variations could be attributed to various factors, including urbanization, industrial discharges, agricultural runoff, and wastewater treatment plant effluents in the Edmonton area. In this case, the implementation of targeted management measures is recommended to reduce the impact of these sources on water quality, such as upgrading wastewater treatment plants, enforcing industrial effluent standards, and promoting best management practices in agriculture.
Seasonal variations
Some of the parameters exhibited seasonal variations. For instance, significant differences in total phosphorus and E.coli concentrations between upstream and downstream stations were observed during the winter but not during the summer season. These seasonal patterns might be related to changes in precipitation, temperature, and land use practices throughout the year, which can influence water quality dynamics. In this cases, it is recommended to implement adaptive management strategies that address seasonal changes in water quality, such as increasing monitoring frequency during high-risk periods, regulating land-use practices to minimize nutrient and sediment runoff, and promoting the use of green infrastructure to reduce urban stormwater pollution.
Consistent parameters
Some water quality parameters, such as pH, dissolved oxygen, total mercury, and total organic carbon, did not show any significant differences between upstream and downstream stations, suggesting that these parameters might be less influenced by the local factors affecting the river. This could indicate that the water quality in terms of these parameters is relatively consistent along the North Saskatchewan River in the studied area.