Groundwater is a major water resource in the North Chengdu Plain, China. The research objective is to determine the quality and suitability of groundwater for drinking purposes within the vicinity of a shallow, unconsolidated aquifer of Quaternary age. In this study, a detailed investigation was conducted to define the hydrochemical characteristics that control the quality of groundwater, based on traditional methods. Considering the uncertainties linked with water resources and the environmental complications, the fuzzy logic method was used in the determination of groundwater quality for more precise findings that support decision-making. To achieve such an objective, sixteen water quality guidelines were used to determine groundwater quality status in six selected wells. The results showed that the groundwater is neutral, very hard, and fresh in nature. Dominating cations and anions are in the order of Ca ${}^{2+}$ > Na ${}^{+}$ > Mg ${}^{2+}$ > K ${}^{+}$ and HCO ${}_3^{-}$ > SO ${}_4^{2-}$ > Cl ${}^{-}$ . The Piper trilinear diagram demonstrates that the hydrochemical facies of groundwater are mostly of Ca-HCO ${}_3$ type. Statistical analysis denotes a positive correlation between most of the chemical parameters. The study took the results of the fuzzy logic evaluation method into consideration, to classify the samples into five groups according to the Chinese groundwater quality standard (GB/T 14848-93) for their suitability for domestic use. The results demonstrated that the quality of the groundwater samples is within grade II and III, and is suitable for drinking purposes. The comprehensive evaluation of groundwater quality is critical to aid sensitive policy decisions, and the proposed approach can guarantee reliable findings to that effect. The results of this study would also be helpful to future researches related to groundwater quality assessment.

The present study proposes a new approach for indexing heavy metals ions to examine groundwater quality in North Kurdufan Province, Sudan. The new approach is developed based on the most frequently used methods for indexing heavy metals pollution in water. It is created in order to avoid the weaknesses of the current indexing systems. As per the new indexing approach, heavy metal contamination in water samples is evaluated by two types of indices: the negative evaluation index (NEI) and positive evaluation index (PEI). The water worthiness is assessed based on a pair of indices, NEI and PEI. Water quality increases with the decrease of PEI and NEI values. NEI indicates the contribution of heavy metals with a concentration not exceeding the highest desirable limit ( $I_i$ ) in the water sample, while vice versa regarding the PEI. If all heavy metals concentrations in the water sample do not exceed $I_i$ , the sum of NEI should be less than zero, but not less than −100, implying that the sum of PEI will be zero. When all heavy metals concentration exceeds $I_i$ , the sum of NEI should be equal to zero, and PEI will be greater than zero. The results of the newly proposed approach have been discussed and compared with the existing indexing methods as regards to the best and worst samples. The spatial distribution of NEI and PEI are in complete agreement with the metals spatial distribution. The comparison result showed that the new index is robust, with fair calculations, and gives the best classification of groundwater quality.

To provide theoretical support for the protection of dispersed drinking water sources of groundwater, we need to accurately evaluate the time and scope of groundwater pollution hazards to human health. This helps the decision-making process for remediation of polluted soil and groundwater in service stations. In this study, we conducted such an evaluation by coupling numerical modeling with a health risk assessment. During the research, soil and groundwater samples were collected and analyzed for 20 pollutants. Fifty-six percent of the heavy contaminants and 100% of the organic contaminants exhibited maximum values at the location of the oil depot. Gray correlation analysis showed that the correlation between background samples and soil underlying the depot was 0.375–0.567 (barely significant to insignificant). The correlation between the reference sequence of other points was 0.950–0.990 (excellent correlation). The correlation of environmental impact after oil depot leakage followed the order: organic pollutants > heavy metals > inorganic pollutants. The groundwater simulation status and predictions indicated that non-carcinogenic health risks covered 25,462 m² at the time of investigation, and were predicted to extend to 29,593 m² after five years and to 39,873 m² after 10 years. Carcinogenic health risks covered 21,390 m² at the time of investigation, and were predicted to extend to 40,093 m² after five years and to 53,488 m² after 10 years. This study provides theoretical support for the protection of a dispersed drinking water source such as groundwater, and also helps the decision-making process for groundwater and soil environment improvement.

The present study was carried out to assess the groundwater quality for drinking purposes in the Quaternary Unconsolidated Sedimentary Basin of the North Chengdu Plain, China. Six groups of water samples (S1, S2, S3, S4, S5, and S6) are selected in the study area. These samples were analyzed for 19 different physicochemical water quality parameters to assess groundwater quality. The physicochemical parameters of groundwater were compared with China’s Quality Standards for Groundwater (GB/T14848-93). Interpretation of physicochemical data revealed that groundwater in the basin was slightly alkaline. Total hardness and total dissolved solid values show that the investigated water is classified as very hard and fresh water, respectively. The sustainability of groundwater for drinking purposes was assessed based on the fuzzy mathematics evaluation (FME) method. The results of the assessment were classified into five groups based on their relative suitability for portable use (grade I = most suitable to grade V = least suitable), according to (GB/T 14848-93). The assessment results reveal that the quality of groundwater in most of the wells was class I, II and III and suitable for drinking purposes, but well (S2) has been found to be in class V, which is classified as very poor and cannot be used for drinking. Also, the FME method was compared with the comprehensive evaluation method. The FME method was found to be more comprehensive and reasonable to assess groundwater quality. This study can provide an important frame of reference for decision making on improving groundwater quality in the study area and nearby surrounding.

Groundwater is a significant and crucial component for all development activities of any life support system. In this study, the hydrochemical analysis and water quality index method (WQI) were used to assess groundwater quality for drinking purposes. Twelve groundwater samples were collected and analyzed into fourteen parameters which were considered as important indicators for assessing groundwater quality. A comparative study of these parameters with that of the Chinese Groundwater Standard (GB/T14848-2017) was conducted. It can be depicted from the results that groundwater quality is categorized as very hard, fresh water and slightly alkaline in nature. The major sequence of dominant cations and anions in groundwater are Ca²⁺ > Mg²⁺ > Na⁺ > K⁺ and HCO^-₃ > SO^2-₄ > Cl^- respectively. From the total 12 samples analyzed, the parameters of TH, NH⁺₄, Fe and Mn of samples exceeded the limits set by (GB/T14848-2017) standard. Piper diagram illustrated that groundwater samples of the studied area are mostly of Ca-Mg-HCO₃-SO₄ type. WQI showed all samples fall between excellent to good category of water and suitable for drinking purposes. The quality of groundwater is mainly affected from anthropogenic activities and natural influence. The proposed method is reliable and effcient for groundwater pollution assessment and can be used in decision-making.

People all over the world inhabit contaminated, areas without being aware of them or the grave health risks they pose. The first step in managing these areas is to identify and delineate the contamination using effective research and monitoring techniques. This paper is geared toward reviewing the chemical characters, and assessment of the quality of exploited groundwater of a gas station in Yinbin City, China. A comprehensive assessment method was used to determine suitability for drinking. The outcomes displayed that most samples of groundwater were contaminated, where the concentration of most physiochemical parameters was above permissible standard levels set by local and international standards for potable water. The Piper diagram showed a difference in the hydrogeochemical characteristics of groundwater in the studied region. Based on the results of the proposed evaluation methods, the F values for all analyzed samples ranged from 4.40 to 7.79, varying from poor quality to very poor quality. Based on a thorough evaluation process, this result shows that all groundwater samples are unfit for public drinking, and do not meet drinking water standards. It follows that it is clear that the gas station poses a risk to the environment at this time.