The coupling effect and ecological risk assessment of iron, manganese, and arsenic in the water environment of the central Yangtze River Basin, China.

Excessive heavy metal in drinking water are harmful to human body. Groundwater was still the drinking water resource in most of rural areas in the central of the Yangtze River Basin. Heavy metals of Fe, Mn, and As in the low plain region of the Yangtze River Basin significantly exceeded the standard, resulting in 16.67% and 5.00% of water samples in the area reaching moderate and severe heavy metal pollution states. However, the coupling effect and ecological risks of iron, manganese, and arsenic in the water environment are unknown. This paper found that the dissolution of iron-bearing and manganese-bearing minerals into groundwater affected each other, when the burial depth of groundwater was less than 20 m. Conversely, the dissolution of minerals containing iron and arsenic into the groundwater interacted with each other when the groundwater depth was greater than 20 m. The precipitation of siderite (FeCO₃) and rhodochrosite (MnCO₃) may control the dissolved Fe and Mn in groundwater. The area between Yangtze River and Han River was more affected by industrial activities, and the south area of the Yangtze River was more affected by agricultural activities. This paper not only strengthened the understanding of the risk of heavy metal pollution in local groundwater, but also provided important scientific basis for the protection of regional groundwater ecological environment.