Distribution Characteristics and Health Risk Assessment of the Heavy Metals in the Centralized Drinking Water Sources in the Typical Townships of Guizhou Province

In order to reveal the pollution characteristics and risk levels of the heavy metals in the drinking water sources in the typical townships of Guizhou,26 centralized drinking water samples were collected in June of 2020 and January of 2021 to detect the heavy metal content including Cr⁶⁺,Pb,Cd,Hg,Fe,Mn,As,Zn and Cu).The health risk assessment model recommended by the US EPA was adopted to evaluate the health risk caused by heavy metals.The results showed that the heavy metal content in the drinking water sources of the 26 towns all met the requirements of the Drinking Water Sanitation Standard （GB 5749—2006）,and the overall pollution degree was relatively low.Seasonal change has a significant impact on the heavy metal concentration in the water source,and the metal concentration in the wet period was 1.0～9.9 times higher than that in the dry season.The water quality in the Karst water resources field was more sensitive to seasonal changes.The health risk assessment results showed that the health risk of water sources in the study area was mainly chemical carcinogenesis risk,and the main risk factor was Arsenic.The health risks caused by non-carcinogenic heavy metals ranged from 10^-12 to 10^-10,and the health risks caused by carcinogenic heavy metals ranged from 10^-10to 10^-7,which were well below the maximum acceptable risk levels recommended by ICRP and EPA.The risk value of different kinds of drinking water sources descended in this order of river>karst water>reservoir.