Trend analysis of nutrient loadings in a large prairie catchment

Nutrient loadings in many river catchments continue to increase due to rapid expansion of agriculture, urban and industrial development, and population growth. Nutrient enrichment of water bodies has intensified eutrophication which degrades water quality and ecosystem health. In this study, we carried out a trend analysis of total phosphorus and total nitrogen loads in the South Saskatchewan River (SSR) catchment using a novel approach to analyse nutrient time series. Seasonal analysis of trends at each of the water quality stations was performed to determine the relationships between annual flow regimes and nutrient loads in the catchment, in particular, the influence of the high spring runoff on nutrient export. Decadal analysis was also performed to determine the long-term relationships of nutrients with anthropogenic changes in the catchment. Although it was found that seasonal and historical variability of nutrient load trends is mainly determined by streamflow regime changes, there is evidence that increases in nitrogen concentration can also be attributed to anthropogenic changes.

受农业、城市与工业的快速扩张以及人口增长的驱动，众多河流流域的营养盐负荷仍在持续攀升。水体营养盐富集加剧了富营养化问题，进而导致水质退化与生态系统健康受损。本研究针对南萨斯喀彻温河（South Saskatchewan River, SSR）流域的总磷（Total Phosphorus）与总氮（Total Nitrogen）负荷开展趋势分析，采用一种新颖的方法解析营养盐时间序列数据。研究对各水质监测站的趋势进行季节性分析，以明确流域内年径流过程与营养盐负荷之间的关联，尤其聚焦春季高径流对营养盐输出的影响。此外还开展了年代际分析，以探究营养盐与流域内人为活动变化之间的长期关联。尽管研究发现营养盐负荷趋势的季节与历史变异主要由径流过程变化主导，但也有证据表明氮浓度的升高也可归因于人为活动带来的改变。