Analysis and evaluation of groundwater pollution in Shouguang, China

Groundwater is an essential nonrenewable resource for agricultural activities. In this study, groundwater samples were collected from the Shouguang area, and the level of groundwater contamination was investigated by measuring the NO₃⁻, SO₄²⁻, F⁻, Cl⁻, Ca²⁺, Mg²⁺, total dissolved solids (TDS) and chemical oxygen demand (COD). Exploratory data analysis was employed initially to study the hydrochemical characteristics and the sources of pollutants. Finally, the groundwater quality was measured using principal component analysis, entropy weight and complex correlation coefficient methods. As a common observation, the groundwater in the Shouguang area is slightly alkaline, so Ca²⁺, Mg²⁺ and NO₃⁻ acted as predominant pollutants. These contaminants originated from the excessive use of chemical fertilizers and large-scale sewage irrigation. Second, perennial overexploitation of groundwater in Shouguang led to the generation of funnels and led to seawater intrusion. As a result, Cl⁻ and TDS in the water samples collected from the north Shouguang area exceeded the regulatory guideline value, which indicates the risk of land salinization. However, the measured concentrations of SO₄²⁻, F⁻ and COD were within the normal range. This confirms the minimal contribution of industries to groundwater pollution. East of the Ni River the groundwater is severely polluted, and the detected concentrations of pollutants are far beyond the standard limit and pose a potential risk to human health. Therefore, protection and treatment are urgently needed.