The Investigation of heavy metals concentration variation and pollution indices of surface sediments of Mashalak River in Nowshahr (Mazandaran province)

Mashalak River is located in the north of Iran and is one of the most important rivers leading to the Caspian Sea west of the Mazandaran province. To conduct environmental monitoring, 25 samples of sediments were collected from the Mashalak riverbed. The samples were analyzed by ICP-MS. A review of heavy metal concentrations suggested that the highest concentrations of heavy metals pertained to Vanadium, Chromium, Zinc, Nickel, Copper, Lead, Cobalt, and Molybdenum, respectively. According to Sediment Quality Guidelines (SQGS), Mashalak sediments are more likely to be contaminated with Chromium and Nickel. The enrichment index shows that Chromium and Nickel produce moderate pollution while other metals have low pollution. Using the Geo-Accumulation Index, only Chromium shows low to moderate pollution. Examining the ecological risk of heavy metals in the Mashalak River deposits suggests these deposits are not contaminated, indicating that the ecological risk of the area under study is low. The Principal Component Analysis (PCA) test results helped identify two main factors. The main factor includes such metals as Cobalt, Aluminum, Vanadium, Copper, Nickel, Zinc, and Chromium, which have both lithogenic and anthropogenic origins simultaneously, as the secondary factor includes the former.