Hydrochemical characteristics and quality assessment of groundwater in Guangxi coastal areas, China

Groundwater is a main source of water supply in Guangxi Province, China. The urbanization expansion and ocean dynamic may change the groundwater quality, which is an important issue due to its effects on human health. In this paper, the influence of seawater intrusion and anthropogenic activity on the Guangxi coastal aquatic environment was assessed by geochemical and multivariate statistical methods. The result indicated that the chemical composition of groundwater in the study area is obviously associated with seawater and the main groundwater types were Ca center dot Na-Cl, Ca center dot Na-HCO3, and Ca-HCO3 center dot Cl. The groundwater evolution path from land to sea in Guangxi is Ca-HCO3. Na center dot Mg-Cl. The origin of salts in the study area is mainly controlled by mineral weathering, the hydrogen and oxygen isotopes contents point to the aqueous source of atmospheric precipitation. According to the results of PCA, seawater intrusion and pollution caused by human activities play an increasingly important role in the evolution of groundwater characteristics. Seawater intrusion is the main factor for the increase of groundwater salinity in Guangxi, while domestic sewage, industrial waste, fertilizers, and pesticides may contribute to the nitrate pollution of groundwater, especially in Beihai. The degree of groundwater nitrate pollution is as follows: Fangchenggang < Qinzhou < Beihai, which is associated with the degree of urbanization in the coastal area. Finally, the results of the water quality index (WQI) assessment show that 82.8 % of the samples were classified as excellent, while there is still a need to be vigilant about groundwater pollution caused by seawater intrusion and groundwater pollution. The results will be valuable for sustainable groundwater resource management in Guangxi coastal zone.

Automated summary

Groundwater quality in Guangxi Province, China is influenced by seawater intrusion and anthropogenic activities. The study found that groundwater composition is associated with seawater, and the main types are Ca·Na-Cl, Ca·Na-HCO3, and Ca-HCO3·Cl. Seawater intrusion and human activities contribute to the evolution of groundwater characteristics, with seawater intrusion being the main factor for increased salinity and human activities causing nitrate pollution. The results highlight the importance of sustainable groundwater resource management in Guangxi coastal zone.