Groundwater is an important source for domestic drinking, agriculture, and industrial activities. However, arsenic and nitrate contamination in groundwater are major world problem and public health concern. This research aimed to evaluate the concentration and spatial distribution of arsenic and nitrate in groundwater of 22 cultivated villages of Chahardoli Plain of Iran by geostatistical techniques and their possible health hazards in local residents. A total of 94 groundwater samples were collected from wells in agriculture areas and analyze for arsenic and nitrate concentrations. Geostatistical analysis and health risk assessment model were applied to investigate spatial distribution, and associated health risks of arsenic and nitrate in groundwater of the study area. The levels of nitrate in groundwater had a range of 3.20–428.00 mg/L with the mean value of 152.95 ± 115.49 μg/L. Nitrate concentration in 73% of samples exceeded the World Health Organization (WHO) acceptable limits of 50 mg/L. Arsenic (As) was found in groundwater which ranged from 0.39 to 220.82 μg/L (mean 30.16 μg/L) and exceeded the WHO recommended level (10 μg/L) for 59% of the groundwater samples. The health risk of nitrate indicated the Hazard quotient (HQ) values suggesting an unacceptable noncarcinogenic health risk. For arsenic, the mean values of HQ for a men, women, and children were.0.24 (0.04–1.54), 0.29 (0.05–1.85), and 0.65 (0.11–4.15), respectively. Generally, exposure to arsenic and nitrate via groundwater depicts that, children were at greater risk followed by women and men. Gold mining was also one of the proposed causes of elevated arsenic concentrations in the northern part of the plain. It can be concluded that in addition to the specific geology of the study area that has led to high concentrations of arsenic in the plain, the spatial distribution of arsenic revealed an increase in the northern part of the region that may be due to the presence of gold mine
