Comparative assessment of some heavy metals in water and sediments from Sawa Lake, South Iraq

The goal of the current study was to assess a few chemical and physical properties, including water temperature and pH, electrical conductivity (EC), dissolved oxygen (DO), biological oxygen demand (BOD5), nitrite (NO2), nitrate (NO3), phosphate (PO4) and the level of some heavy metals, like lead, cadmium, zinc, iron, manganese and nickel in water of Sawa Lake, Iraq. Three locations were selected in Lake. The samples were taken on a monthly basis from October 2021 to February 2022. The results indicated that the water temperature varied between 13.4 and 25.25 ºC, pH values 8.06 - 9.70, electrical conductivity 27984.33- 65622.3 µs cm-1, dissolved oxygen 0.0-4.3 mg L-1, biochemical oxygen demand (BOD5; 2.58-8.08 mg L-1), nitrite 1.14-8.02 µg L-1, nitrate 0.65-57.19 µg L-1 and phosphate 0.20-8.11 µg L-1. The study results of heavy metals concentrations in water were as follows: lead (Pb; 0.00-0.34 mg L-1), cadmium (Cd; 0.00-0.007 mg L-1), zinc (Zn; 0.00-0.036 mg L-1), iron (Fe; 0.21-0.78 mg L-1), manganese (Mn; 0.00-0.10 mg L-1), and nickel (Ni; 0.00-0.10 mg L-1).  While in sediments, elements concentrations were as follows: Pb 2.66-27.15 mg kg-1, Cd; 0.001-0.62 mg kg-1, Zn 10.92-17.07 mg kg-1, Fe 1382.56-2268 mg kg-1, Mn 63.20-154.98 mg kg-1, and Ni 7.33-23.51 mg kg-1.   The water quality of Sawa Lake under this study was exceeding the permissible limit for PH, EC, BOD5 and NO3. Increasing levels of heavy metals in the Sawa Lake water and sediment were over the allowable limit, implying heavy metal water pollution.