*3.2. Groundwater Quality Assessment*

In this study, pH, TDS, TH, SO<sup>4</sup> <sup>2</sup>−, Cl−, F−, volatile phenols, NO3-N, NO2-N, NH4- N, Fe, Mn, Hg, Cd, Cr6+ and Pb are selected as the parameters to evaluate the overall groundwater quality, using the WQI introduced previously. The values of cyanide, arsenic, and chemical oxygen demand in groundwater are very low, so they have little impact on water quality and can be ignored in water quality assessment. The weights and relative weights assigned to each parameter are shown in Table 4.


**Table 4.** Relative weight of hydrochemical parameters.

Units for all parameters are in mg/L, except pH (non-dimensional).

The calculated WQI values and water types are presented in Table 5. The results of WQI range from 23.63 to 105.96. Out of 10 groundwater samples, sample S5 is categorized as good water. Sample S10 is classified as poor water. The other 8 samples are excellent water. For the study area, the most significant parameters affecting groundwater quality are Pb, TH, F−, SO<sup>4</sup> <sup>2</sup>−, and TDS.


**Table 5.** Water quality index values and water types in the study area.

From the spatial distribution of groundwater quality index results, it can be seen that poor quality water area is mainly located near Yicheng in the southeastern area of the study (Figure 3). The main pollutants in the groundwater in this area are TH, TDS, SO<sup>4</sup> <sup>2</sup>−, Fe, Mn, and Pb, all of which exceed the upper limit for drinking purposes. The poor groundwater quality in Yicheng may be related to the buried depth of groundwater. Generally, when the groundwater is buried deeper, it takes longer for the surface pollutants to reach the aquifer. Thus, the possibility of the pollutants being adsorbed and diluted during the infiltration process becomes greater, and the degree of pollution in the groundwater system will decrease. The buried groundwater depth in the Yicheng area is shallow at 2–15 m. In addition, the lithology of the buried deep aquifer is mainly coarse sand and medium-coarse sand. The better permeability of the aquifer makes it easier for surface pollutants to seep into the groundwater, resulting in groundwater pollution. Fe and Mn in groundwater come from coal and metal deposits, especially iron ore. High TDS leads to increased ionic strength and decreased activity coefficient, which will dissolve more Fe and Mn in groundwater. In addition, the organic matter released from surface pollutants into groundwater can quickly deplete the dissolved oxygen in groundwater, resulting in a reductive hydrochemical environment more conducive to the dissolution of Fe and Mn [77]. *Water* **2022**, *14*, x FOR PEER REVIEW 12 of 19

**Figure 3.** Spatial distribution of groundwater quality based on water quality index values.

**Figure 3.** Spatial distribution of groundwater quality based on water quality index values.

safe water supply measures should be implemented as soon as possible.

by excellent water that can be used for drinking purposes. For the Yicheng area with poor quality groundwater unsuitable for drinking, groundwater pollution remediation and

The health risks of groundwater in the study area were assessed based on the model

introduced previously. The calculated health risks for adults and children through drinking water and dermal contact are shown in Table 6. For adult males, the HQoral values range from 0.285 to 0.827, with a mean of 0.521. The HQoral values for adult females and children range from 0.336 to 0.976 and 0.693–2.012, with an average of 0.615 and 1.269, respectively. The HQdermal values are smaller than the HQoral, ranging from 0.017 to 0.104 for males, 0.018 to 0.109 for females, and 0.026 to 0.156 for children, with means of 0.034, 0.036, and 0.051, respectively. This suggests that non-carcinogenic risk is mainly caused by oral exposure. The HItotal values for males and females range from 0.302 to 0.902 and 0.354–1.051, with means of 0.555 and 0.651, respectively. For children, the HItotal values are 0.719–2.100, with an average value of 1.320. For males, females, and children, HItotal values of 0%, 20%, and 80% of the samples exceed 1, indicating that males in the study area do not have associated non-carcinogenic health risks. In contrast, females and children face higher non-carcinogenic risks. Females and children have smaller body weights and

therefore have higher average daily exposure dose of contaminants than males [50,60].

**Table 6.** The non-carcinogenic and carcinogenic risk results from drinking water and dermal con-

**HQoral HQdermal HItotal**

S1 0.393 0.463 0.956 0.018 0.019 0.027 0.411 0.482 0.983

S2 0.285 0.336 0.693 0.017 0.018 0.026 0.302 0.354 0.719

S3 0.436 0.514 1.060 0.018 0.019 0.028 0.454 0.533 1.088

S4 0.529 0.625 1.288 0.019 0.020 0.029 0.548 0.644 1.317

S5 0.827 0.976 2.012 0.043 0.045 0.065 0.870 1.021 2.077

S6 0.799 0.942 1.943 0.104 0.109 0.156 0.902 1.051 2.100

**Males Females Children Males Females Children Males Females Children** 

*3.3. Human Health Risk Assessment* 

tact.

**The Non-Carcinogenic Risk** 

**Sample** 

The assessment results indicate that the groundwater in the study area is dominated by excellent water that can be used for drinking purposes. For the Yicheng area with poor quality groundwater unsuitable for drinking, groundwater pollution remediation and safe water supply measures should be implemented as soon as possible.
