The groundwater environmental effects and health risk assessment in saline-fresh water mixing zone of coastal plain

Abstract

The groundwater environment is important to human living in coastal plain. In this study, southern Laizhou Bay (SLB) is chosen as the study area and 47 groundwater samples are collected to analyze groundwater environmental effects and health risk assessment in saline-fresh water mixing zone (SFMZ) of coastal plain. Influenced by saline water intrusion (SWI), K+, Na+, Ca2+, Mg2+, Cl-, SO42- and HCO3- concentration values are exceeded WHO standard value seriously. High-F groundwater is the product in process of SWI, caused by cation exchange, weakly alkaline environment, evaporation and fluorite dissolution. Na+ concentration and a decrease in the Ca2+ concentration can promote further dissolution of fluorite and other F-containing minerals. Based on the health risk assessment method, the average HQ sequence in typical groundwater pollutants is Cl- > F- > NO3-N > Se > Mn > NO2-N > Cu > Pb > Zn > Fe, and the CR sequence caused by carcinogenic heavy metals is Cd > As > Cr. The greatest non-carcinogenic risk to adults and children in the study area is caused by Cl-. Cd is the most important indicator of carcinogenic risk, and its contribution to CR accounts for 74.531%. The regions with high health impacts of carcinogenic pollutants in groundwater are mainly concentrated in the central part of the study area, with the exceeding range of 35.373% for adults and 44.768% for children. Non-carcinogenic pollutants are enriched in SFMZ, which have greater impacts on human body and lead to higher health risks compared with carcinogenic pollutants.