Hydrochemical characteristics, evolution and health risk assessment of surface water and groundwater in Lhasa, China

Lhasa, perched atop the Qinghai Tibet Plateau, has particular hydrochemical evolution characteristics as well as a distinct biological habitat. Rapid development has jeopardized the surface and groundwater. To maintain water safety and community health, a scientific examination of groundwater quality and human health problems is essential. A complete investigation of Lhasa's hydrochemical evolution was carried out using 65 water samples, including 14 surface water samples and 51 groundwater samples, and the quality of the surface and groundwater was assessed. Health hazards were also assessed. According to the findings, both surface water and groundwater have decreased salinity, hardness, and alkalinity. According to the Comprehensive Weighted Water Quality Index statistics, the average water quality indices for surface water and groundwater are 16.28 and 14.14, respectively, indicating good water quality. Surface and groundwater are suitable for agricultural irrigation due to their low salt absorption rates. According to the study of hydrochemical development and regulating factors, rock weathering is a phenomenon that affects both surface water and groundwater. Water is unaffected by precipitation or human actions. According to the human health risk assessment, children have a higher risk of non-carcinogenicity than adults, and the primary exposure route is daily oral ingestion. Non-carcinogenic health risk indices for nitrate consumption in children and adults are 0.220 and 0.136, respectively, indicating a lower non-carcinogenic risk of nitrate in the region's surface and groundwater, and the younger the age, the higher the non-carcinogenic health risk of nitrate intake. This study provides data support for local water resource management and optimization, as well as a reference for the chemical evolution of urban water and the evaluation of nitrate non-carcinogenic risk in global alpine regions.