Assessment of Mercury (Hg) and Cyanide (CN) Pollution in Surfacewaters, Groundwaters and Sediments around Industrial Mining Sites in the Department of Divo (Ivory Coast)

Abstract

Contamination of water and sediments by trace metal elements constitutes a risk to water, living species and for human health. The objective of this study is to assess the level of contamination of water and sediments in the Divo mining area with trace elements. Trace elements (CN and Hg) were determined in water and sediments using an Inductive Coupled Plasma Atomic Emission Spectrometer (ICP-AES). The intensity of sediment contamination was estimated from the calculation of several indices, including the Contamination Factor (FC), the Modified Contamination Degree (DC m ) and the Sediment Pollution Index (SPI). The results of the monitoring of the seasonal evolution of TME (CN and Hg), during the months of September 2018 and February 2020 are as follows: In surface water, the metallic concentrations vary from 0 to 4. 98 μg/L for mercury and 0 to 95 μg/l for cyanide. All surface water samples have mercury concentrations lower than the average reference concentration of 6 μg/L. 7% of surface water samples have cyanide concentrations above the average concentration of 70 μg/L. Concerning groundwater, the cyanide concentrations remained below the standards for drinking water over the two seasons. Mercury recorded high concentrations in wells in the department. The sediments were found to be polluted with CN (uncontaminated to low contamination/very heavily contaminated) and Hg (uncontaminated to moderately contaminated/very heavily contaminated). The IPS values show that the surface sediments are moderately polluted except at the HR6 stations (0.07); ZR3 (0.22); AR1 (1.15); R3 (0.96); BRR (0); DRV (0.07) where the sediments are healthy. The inhabitants of mining areas are exposed to the risk of contracting various diseases by consuming this water contaminated with these trace elements.