Spatio-Temporal Analysis of Heavy Metal and Eutrophication Indicators in Barzewa River: A Brief Winter Assessment of the Consequences of Untreated Sewage Dumping in Soran district in Erbil Province

The discharge of untreated wastewater into natural waterways poses a significant threat to aquatic ecosystems and human health. This study assessed the impact of raw sewage discharge on the water quality of the Barzewa River in Soran District, Kurdistan, Iraq. The investigation was conducted over December 2022 till February 2023, utilizing a spatial gradient design with four sampling locations: upstream of the discharge (L1), at the mixing point (L2), and 50m (L3) and 100m (L4) downstream. A comprehensive suite of physicochemical, biological, and heavy metal parameters was analyzed, including pH, EC, TDS, TSS, DO, BOD, NO3-, total alkalinity, major cations, heavy metal concentration, and total coliform bacteria. The most severe impact was recorded at location 2 (the mixing point). Key pollution indicators peaked here, with maximum values including EC 396.5 (S/cm), BOD 2.8 (mg/L), NO3- (12 mg/L), and a significant total coliform count (3.69x106/100ml). Total alkalinity, TSS, and total coliform levels exceeded standard permissible limits, indicating microbiological and organic contamination. Heavy metal analysis revealed that zinc concentrations surpassed the WHO permissible limits water at all four locations. Chromium also exceeded limits at L1 and L2. Concentrations of arsenic, cadmium, copper, lead, and others were below permissible levels. Overall, the study clearly demonstrates a significant and immediate water quality impairment along the river within the study area, primarily driven by organic load, coliform bacteria, and specific heavy metals. These findings underscore the urgent need for improved sewage treatment and enhanced water quality monitoring to safeguard this vital freshwater resource