Hydrogeochemical characterization and human health risks associated with groundwater nitrate concentrations in the Saiss basin, Morocco

Groundwater has been facing not only prolonged climate change-induced groundwater shortage but also severe deterioration of groundwater quality from natural and/or anthropogenic sources. This study aims to determine the hydrogeochemical processes controlling groundwater chemistry in the Saiss basin, Morocco, and to assess seasonal changes in groundwater quality using the entropy-weighted water quality index (EWQI). In addition, human health risks associated with groundwater nitrate (NO 3 − ) contamination/pollution were investigated using the hazard quotient (HQ). Groundwater chemistry in the Saiss basin was mainly controlled by mineral dissolution/precipitation and direct cation exchange, with slight seasonal variations in the saturation indices (SIs). The EWQI suggested slight groundwater quality deterioration in the dry season due to increased NO 3 − concentrations. In fact, children were over two times exposed to non-carcinogenic issues associated with groundwater NO 3 − concentrations when compared with adults. The current study provides further insights into the hydrogeochemical characteristics of groundwater to ensure safe regional water supplies. • Rock weathering/ion exchange were the main processes driving groundwater chemistry. • Seasonal variations in the saturation indices of minerals were observed. • Nitrate obviously exceeded the corresponding drinking threshold (50 mg/L). • Slight seasonal changes in groundwater quality were found. • Children were over two times exposed to non-carcinogenic risks of nitrate.