Distribution, risk assessment of heavy metals in sediments, and their potential risk on water supply safety of a drinking water reservoir, middle China.

Abstract

Heavy metals in reservoir sediments were analyzed to assess the pollution level and to understand the potential risk on water supply safety. Heavy metals in sediments will enter the biological chain through bio-enrichment and bio-amplification in water and eventually pose a threat to the safety of drinking water supply. Analysis of eight sampling sites in JG (Jian gang) drinking water reservoir of the sediments showed that from Feb 2018 to Aug 2019 heavy metals including Pb, Ni, Cu, Zn, Mo, and Cr increased by 1.09-17.2%. Vertical distributions of heavy metals indicated that the concentrations increased gradually by 9.6-35.8%. Risk assessment code analysis indicated that Pb, Zn, and Mo were of high risk in the main reservoir area. What is more, enrichment factors of Ni and Mo were 2.76-3.81 and 5.86-9.41, respectively, showing the characteristics of exogenous input. The continuous monitoring results of the bottom water showed that the concentration of heavy metals in the bottom water exceeded the environmental quality standard value of surface water in China, and exceeded the standard by 1.76 times (Pb), 1.43 times (Zn), and 2.04 times (Mo), respectively. Heavy metals in the sediments of JG Reservoir, especially in the main reservoir area, have a potential risk of release from the sediment to the overlying water. Water supply reservoir as a source of drinking water, its quality is directly related to human health and production activities. Therefore, this first study on JG Reservoir is of great significance for the protection of drinking water safety and human health.