Isolation and Diagnosis of Some Bacterial Species from Samarra Thermal Station Effluents in Al-Ishaqi Subdistrict and Their Relationship with Certain Physical and Chemical Variables

   This study aims to evaluate the seasonal variations in the physical, chemical, and biological characteristics of the Tigris River water at the Al-Ishaqi region, focusing on the impact of industrial waste from the Samarra Thermal Power Plant and surrounding human activities. As the study revealed significant variations in the physical, chemical, and biological properties of the Tigris River water at the Al-Ishaqi area during the autumn and winter seasons, attributed to the influence of discharges from the Samarra thermal power plant and surrounding human activities. Water temperature decreased in winter (17.3°C) compared to autumn (22°C), which negatively affected microbial activity. Biochemical Oxygen Demand (BOD) levels increased to 3 mg/L in winter, indicating a rise in organic pollutants. Total hardness, as well as calcium and magnesium hardness, reached their highest values in winter—800, 540, and 260 mg/L, respectively—due to surface runoff and salt accumulation. Elevated concentrations of nitrates (24.68 mg/L) and potassium (4.47 mg/L) were also observed in the discharge area during winter, while phosphate and sodium levels showed no significant differences. Bacteriological analyses showed a marked increase in total bacterial count during winter (6×10⁶ cells/mL) compared to autumn, with the isolation of pollution-indicating bacterial species such as Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus, particularly near discharge points. These results highlight a clear impact of the plant’s effluents on water quality, especially during the winter season, necessitating measures to mitigate pollution and improve water treatment before use for drinking and domestic purposes.