Evaluation of Element Pollution (Cd, As Cu, Zn) in Estuaries of Western Rivers of Mazandaran Province, Iran

The purpose of the present study was to assess the concentration of Cd, As, Cu, and Zn metals in water and sediments of rivers in the west of Mazandaran province, Iran. The number of water and sediment samples was 36 taken from four stations from April 2019 to March 2020 and analyzed with three replicates. Mean values of total environmental factors at the four stations during winter and summer seasons were as T=11.21-16.46 °C, salinity=3.58-6.47 g/l, pH=5.42-5.92, TDS=3.52-6.25 g/l, electrical conductivity=6.27-11.12 μmho/cm, nitrite=0.01-0.03 mg/l, and nitrate=1.37-3 mg/l respectively. The quality of environmental factors was found within the normal range for water quality in Iran for different types of land use: agricultural, industrial, recreational, and hot-and cold-water fish farming. Mean values of total adsorption of cadmium, arsenic, copper, and zinc were 0.25, 0.77, 11.44, and 11.02 mg/l respectively in water samples, and 0.2, 3.83, 20.91, and 59.27 μg/g in sediment samples. The adsorption of all metals was higher at the beginning of the cultivation season compared with the non-cultivation season both in water and sediment samples. Safarood river was the most polluted of all rivers. The concentration of metals was higher than the permissible limit in water, but lower in sediments (except for copper and arsenic) in all four rivers.