Evaluation of Heavy Metals in Water and Sediments of Haraz River, Using Pollution Load Index (PLI) and Geoaccumulation Index (Igeo)

In recent years, toxic and chemical effluents from agricultural and industrial activities have entered into surface waters without considering environmental considerations, which has caused water pollution, contamination of river sediments and many environmental hazards. In this study, the concentration of four heavy metals of arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in water and sediments of Haraz River in Mazandaran province was investigated using Contamination Factor (CF), Pollution Load Index (PLI) and Geoaccumulation Index (Igeo). The results showed that the concentration ranges of arsenic (AS), chromium (Cr), cadmium (Cd), and lead (Pb) in water are 3.03- 3.99, 2.55-3.92, 1.94-2.42, and 3.96-5.3 mg/lit, and in sediment are  2.12-5.15, 29.91-32.71, 1.02-1.03, and 6.62-9.46 mg/kg, respectively. The concentration of heavy metals in downstream sites (S7 and S8) were higher than the standard drinking water, due to the disposal of waste, untreated effluents from various industries and excessive agricultural activities. The pollution load index (PLI) of  heavy metals in sediment samples was in low and medium pollution level and the Geoaccumulation Index (Igeo) in sediment samples was in the level of no and medium pollution. This study suggests a continuous monitoring of heavy metals in water, sediments and other aquatic biomasses, which is crucial in Haraz River to ensure the environmental safety adjacent to the river.