Water quality assessment in the Pangani River basin, Tanzania: natural and anthropogenic influences on the concentrations of nutrients and inorganic ions

The ongoing rapid expansions of human activities and population dynamics have a potential impact on the environmental quality of the Pangani River basin, one of the largest water resources in Tanzania, including possible loadings of different kinds of micro-contaminants. However, the specific extent of the impacts is not well investigated. In this work, we assessed the environmental quality of the basin, based on the seasonal characterization of physicochemical water and sediment parameters, dissolved inorganic ions and nutrient loads. The contributions of geochemical processes and land-use practices were evaluated by multivariate correlations and principal component analysis (PCA). Hierarchical cluster analysis was used to classify similar water quality stations and identify the most and least enriched ones. Surface waters were slightly alkaline, characterized by low total dissolved solids (48–652 mg/L). Extremely low oxygen concentration (2.0 mg/L) was also a cause of concern at one station. The Na+ and...