Comprehensive assessment of water quality and associated health risk by using physicochemical quality indices and multivariate analysis in Terme River, Turkey

The ecosystem and water quality of Terme River, an essential drinking and irrigation water source in the region, are at risk due to anthropogenic pressures. Therefore, the present study aim to present a comprehensive overview of the water quality state and pollution sources of the river. Some physicochemical water quality parameters were analyzed by standard methods along the surface water of river spatiotemporally. The concentrations of major elements and heavy metals (Na, Mg, K, Ca, Al, Cr, Fe, Co, Mn, Ni, Zn, Cd, Cu, Pb, As) were measured in water samples. Relationships between physicochemical data were assessed by using multivariate statistical analysis (MSA) methods. The order of the mean values of cations were as follow: Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ > NH₄⁺ (32.66, 26.82, 13.29, 6.45, 0.305; mg/L), and order of anions: SO₄²⁻ > NO₃– >F⁻ > NO₂– (7.88, 3.988, 1.01, 0.0316; mg/L). Increases in ion concentrations in the downstream zone have been monitored in the summer and autumn months. Average water quality index (WQI) 22, heavy metal pollution index (HPI) 15.61, heavy metal evaluation index (HEI) 0.78, and nutrient pollution index (NPI) 0.404 values indicated that the general water quality of Terme River was fine. All hazard quotient (HQ) and hazard index (HI) values in this study were calculated below the risk threshold (<1). HI-total values (2.48E-01) in children were higher than in adults (2.14E-01). This suggests that children’s health is at higher risk than adults. Principal component analysis (PCA) data formed four principal components (PCs) explaining 85.22% of the total variance. These PCs revealed that the significant changes in water quality occurred from point and diffuse sources, including rock types of the basin, soil erosion, domestic wastewater discharges, and agricultural flow of inorganic fertilizers.