Occurrence, Species, and Health Effects of Groundwater Arsenic in Typical Rural Areas Along the Northern Foot of the Qinling Mountains, China

This research focused on the major water quality parameters and trace elements in 73 groundwater samples collected from some rural areas at the northern foot of Qinling Mountains, and the hydrochemical characteristics of groundwater in this area were investigated. The distribution and enrichment of arsenic (As) in groundwater were specifically explored, the different chemical species of arsenic were calculated using PHREEQC, and the carcinogenic and non-carcinogenic health risks caused by total arsenic were assessed using probabilistic models. The results showed that the concentration of arsenic in groundwater ranged within 1.46–8.69 μg/L, which is close to the World Health Organization's guideline value recommended for drinking water (10 μg/L). The chemical species of arsenic simulated using the PHREEQC model showed that the main species of arsenic in most groundwater samples in the study area were HAsO 4 2− and H 2 AsO 4 − , while the main species of arsenic in a few samples were H 3 AsO 3 , followed by H 3 AsO 4 , AsO 4 3− , AsO 3 3− , HAsO 3 2− , and H 4 AsO 3 + , which were present in a relatively small proportion. Changes in environmental acidity and redox conditions had significant effects on the species of arsenic present in groundwater. The results of the health risk assessment showed that the non-carcinogenic risk of human health due to exposure to arsenic is 3.19 × 10 –5 and 1.11 × 10 –4 for adults and children, respectively. Children are at greater health risk than adults.