Evaluating the Effect of Urban Anthropogenic Activities on Water Physicochemical Characteristics Along Morogoro River and the Potential Risks to the Ecosystem

Abstract

This study evaluated the physical chemical characteristics of surface water along the Morogoro River in Morogoro Municipality, Tanzania, to assess the effects of urban activities on water quality. Five sampling sites were selected across the river’s urban stretch, with samples analyzed for in-situ parameters, nutrients and heavy metals. Results showed elevated concentrations of some parameters at sampled points, i.e. Nitrate (NO₃^-) levels ranged from 4.22 ± 2.094 to 17.467 ± 7.003 mg L^-1, sulphate (SO₄^2-) levels ranged from 13.43 ± 0.205 to 28.77 ± 1.633 mg L^-1, and ammonia (NH₃) ranged from 0.234 ± 0.008 to 0.737 ± 0.053 mg L^-1. Heavy metals including copper (Cu), ranged from 0.221 ± 0.008 mg L^-1 to 0.802 ± 0.0105 mg L^-1, zinc (Zn) ranged from 0.41 ± 0.255 mg L^-1 to 2.63 ± 0.50 mg L^-1 exceeding the EAS and WHO guidelines in several cases. The values of lead (Pb), ranged from 0.39 ± 0.019 to 14.53 ± 0.735 mg L^-1, exceeded the EAS and WHO limit of 0.01 mg L^-1 at all sampled points. The results indicate the river water pollution from domestic wastewater, agricultural runoff, and car wash sites. Statistical analyses, including Principal Component Analysis (PCA) and cluster analysis, revealed strong spatial correlations (Pearson coefficients of 0.92-0.99) and a dominant anthropogenic source of contamination explaining 96.9% of the variance. Given the potential health risks associated with heavy metal exposure, the study recommends the establishment of designated and regulated car wash bays equipped with wastewater treatment systems. This, alongside routine water quality monitoring and stricter enforcement of waste management guidelines, is critical for protecting public health and preserving the ecological integrity of urban rivers in rapidly urbanizing regions.