Sources and health risk assessments of nitrate in groundwater, West of Tahta area, Sohag, Egypt

Due to natural and anthropogenic human activities in arid and semi-arid regions, groundwater will continuously suffer from severe contaminations such as increases in nitrate levels. Groundwater contamination poses serious threats to the environment and human health. In the current study, 23 groundwater samples were collected from the desert zone around the wastewater treatment plant west of Tahta area, Sohag, Egypt. The samples were chemically and bacteriologically analyzed to quantify the sources and potential risk of nitrate in groundwater to the health of adults, children and infants. The nitrate showed wide spatial variability in the studied area, with values going from 0.38 up to 59 mg/L. Based on the bacteriological, principal component, NO3- and NO3-/Cl- analyses, nitrate in the south-western parts around the wastewater treatment plant developed from the sewage contamination while the northeastern and southern parts are mainly due to contamination from the agricultural activities and organic wastes. The non-carcinogenic hazard quotients (HQ) values of 78% of infants, 70% children and 4% of adults were higher than the safety level (i.e., HQs>1), suggesting severe health effects on human health. Proper management of wastewater disposal activities and application of fertilizers are required to reduce groundwater contamination in Egypt and globally.