Abstract
The study was conducted from July 2022 to June 2023 to investigate the seasonal biological, chemical, and physical changes in the waters of the Tigris River and their impact on the city of Tikrit. The results showed significant temporal variations in water temperature for all study stations, with the lowest values occurring in winter and the highest in summer. The biological oxygen demand (BOD) also exhibited temporal and spatial differences, with lower values in summer and spring and higher values in winter. Total dissolved solids (TDS) exhibited significant temporal and spatial variations at a significance level of p ≤ 0.05, with lower values in summer and higher values in winter. Calcium ion (Ca²⁺) levels showed significant temporal variations, with the highest values in winter and spring and the lowest in summer. Magnesium ion (Mg²⁺) levels exhibited temporal and spatial differences, with lower values in summer and higher values in winter. Sodium ion (Na⁺) levels showed temporal variations but not significant spatial differences, with the highest values in winter and the lowest in spring. Potassium ion (K⁺) levels exhibited temporal variations, with higher values in winter and spring and lower values in autumn. Nitrate (NO₃⁻) levels showed temporal variations, with the highest values in summer, autumn, and winter, and the lowest in spring. Phosphate (PO₄³⁻) levels exhibited temporal and spatial differences, with the highest values in summer at the fifth station and the lowest values in summer at the third station.
Bacterial species were isolated from the water samples, and some predominant bacterial species were identified, including Escherichia coli, Klebsiella spp., Staphylococcus spp., Aeromonas sobria, Citrobacter amalonaticus, Enterobacter aerogenes, and Salmonella enterica.
Keywords: Filtration stations, bacteria, physical and chemical variables.
