Evaluation of heavy metals contamination in sediments and hydrogeochemical characteristics of water in Mashalak River, North Iran

The present study was conducted aimed to determine the concentration of heavy metals for environmental assessment of water and surface sediment samples taken from the Mashalak River in northern Iran. Sediment and water samples were analyzed by ICP-MS and the concentration of conventional cations and anions was also measured. Results showed that V, Cr, Zn, Ni, Cu, Pb, Co, and Mo had the highest concentration of heavy metals. The geo-accumulation index indicated low-moderate pollution and the ecological risk assessment showed low ecological risk in the study area. There was a positive and significant relationship between metals, indicating a common origin and similar geochemical behavior. The results of the hydrogeochemical assessment showed that the water of the Mashalak River is in the inappropriate quality range only in terms of residual sodium carbonate (RSC). At the stations near the wastewater, the concentration of As and Cr is high, and the water of these stations is not suitable for drinking. The changes in the pattern of heavy metals along the river showed an increase in these pollutants next to the wastewater station. Based on the classification of drinking water by metal concentration and pH, the water of Mashalak River is in the class of near neutral at a low concentration, which is not an environmental concern.