An analysis of data from 339 groups of inorganic groundwater samples collected in a typical area of the Huai River Basin shows that shallow high-iodine groundwater is widely distributed in the northern and northeastern parts of the research area, followed by the region near Taikang. Deep high-iodine groundwater is distributed mainly in the southern part, followed by the area near Kaifeng. The main source of iodine in groundwater is iodine from Quaternary loose sediments. Climate, rock weathering, evaporation, crystallization, groundwater flow field, and pumping groundwater for irrigation all lead to the gradual concentration of iodine in groundwater and thus the formation of high-iodine groundwater.
Yonghong et al. (Fri,) studied this question.