Abstract
To investigate the quality of domestic groundwater and assess its risk to inhabitants of the Guanzhong Basin, China, 191 groundwater samples were collected to analyze major ions, nitrate, pH, total dissolved solids (TDS), total hardness (TH), and electrical conductivity (EC). The physiochemical parameters, hydrochemical facies, and sources of major ions were analyzed using Durov diagrams, bivariate diagrams, and chloro-alkaline indices (CAI-I and CAI-II). The suitability of groundwater for drinking, the nitrate distribution, and human health risk (HHR) for different age groups were evaluated. The results showed that the relative abundance of cations in the groundwater samples was K++Na+ > Ca2+ > Mg2+, while that of anions was HCO3− > SO42− > Cl− > NO3−. Groundwater samples mainly contained HCO3-Na and HCO3-Ca, which were introduced mainly by rock weathering and ion exchange. The groundwater in the Guanzhong Basin contained mainly good and medium water, and the groundwater in the southern part of the Wei River was better than that north of the Wei River. Areas containing high nitrate concentrations were mainly located in the central and western parts of the Guanzhong Basin. The percentages of low risk (<45 mg/L), high risk (45–100 mg/L), and very high risk (>100 mg/L) of nitrate pollution in the study area were 90.58%, 8.9%, and 0.52%, respectively. The HHR assessment results indicated that people in the 6–12 month age group were more likely to suffer from health complications due to a higher nitrate concentration, followed by 6–11 years, 21–65 years, 18–21 years, ≥65 years, 11–16 years, and 16–18 years age groups, which was mainly due to the different exposure parameters. The results of this study will be useful in regional groundwater management and protection.
Highlights
Groundwater is extensively used for agricultural, industrial, and drinking purposes in many arid and semi-arid regions (e.g., Western United States, Algeria, Egypt, China, and Australia) where rainfall is infrequent and surface water is scarce [1,2,3,4]
The main objective of this study was to (1) study the hydrogeochemical characteristics, hydrochemical facies of groundwater, and their formation mechanisms; (2) appraise the overall groundwater quality for drinking purposes using the water quality index (WQI); (3) analyze the distribution and main sources of nitrate in the Guanzhong Basin; and (4) assess the non-carcinogenic health risks posed by drinking nitrate-contaminated groundwater for different age groups (6–12 months, 6–11 years, 11–16 years, 16–18 years, 18–21 years, 21–65 years, and ≥65 years)
All samples were analyzed for various hydrochemical parameters, such as pH, total dissolved solids (TDS), electrical conductivity (EC), total hardness (TH, as CaCO3 ), potassium and sodium (K+ +Na+ ), calcium (Ca2+ ), magnesium (Mg2+ ), chloride (Cl− ), sulfate (SO4 2− ), bicarbonate (HCO3 − ), and nitrate (NO3 − ). pH and TDS were measured immediately in the field using portable devices, and EC was calculated from TDS
Summary
Groundwater is extensively used for agricultural, industrial, and drinking purposes in many arid and semi-arid regions (e.g., Western United States, Algeria, Egypt, China, and Australia) where rainfall is infrequent and surface water is scarce [1,2,3,4]. Groundwater accounts for only 29.9% of all global freshwater resources [1,5], and water resource shortages have become one of the most important challenges to humankind [4,6]. Groundwater resources have drastically declined in quality and in quantity due to untreated effluents from industrial and agricultural development, expanding urbanization, population growth, inadequate sanitation, and pollutant runoff in arid and semi-arid regions [2,7,8]. Public Health 2019, 16, 4246; doi:10.3390/ijerph16214246 www.mdpi.com/journal/ijerph
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