Abstract Due to rapid economic growth and over-exploitation of groundwater, nitrate pollution in groundwater has become very serious. The main objective of this study is to modify the DRASTIC model to identify groundwater vulnerability to nitrate pollution. The DRASTIC model was firstly used to analyze the intrinsic vulnerability. The DRASTIC model with the inclusion of a land-use factor (DRASTIC-LU) was put forward to map the specific vulnerability of groundwater. Furthermore, the support vector machine (SVM) was introduced to avoid the drawback of the overlay and index methods, and the improved integrated models of DRASTIC + SVM and DRASTIC-LU + SVM were built. Moreover, 103 groundwater samples were collected for building and validating the models. The Root Mean Squared Error (RMSE) of DRASTIC, DRASTIC-LU, DRASTIC + SVM, and DRASTIC-LU + SVM was found to be 0.853, 0.755, 0.631, and 0.502, respectively. The model DRASTIC-LU was more precise than the original one. The results also showed that the integrated model using SVM exhibited better correlation between the vulnerability value and the nitrate pollution. The study indicated that the modified models including the land-use factor as well as SVM in the DRASTIC model were more suitable to assess the groundwater vulnerability to nitrate.
The fluoride contained in the filter liquor produced by fly ash in the thermal power plant which takes the coal as fuel can lead to groundwater pollution. Therefore, it is of great significance to study the migration characteristics of the pollutants in groundwater, in order to control and prevent the groundwater fluoride pollution. By adopting the numerical modeling method, this paper takes the ash-storage yard of Shahe Power Plant in Xingtai City as an example, to study the characteristics of fluoride migration in phreatic water, and establish a two-dimensional groundwater flow and water quality model on the basis of the hydrogeological condition analysis in this study area. Meanwhile, based on the Vmodflow software, the migration regulation of the fluoride in groundwater has been simulated. Because the phreatic aquifer of this area belonging to the Shahe alluvial-diluvial sediments and with a coarse lithology as well as high permeability, the migration and diffusion ability of the fluoride in this area is relatively strong. It turns out that the longest migration distance in 5 years is 892 m and that within 8 years is 1515 m.
The groundwater in Gaobeidian city is used for drinking, irrigation, industrial production, and other purposes. With the rapid development of the economy and urbanization, groundwater quality has been seriously affected. The main purposes of this paper are to evaluate the groundwater quality in the study area on the basis of understanding the hydrochemical characteristics of the study area and assess the possible health risks of groundwater to children and adults. In this paper, the entropy weight method was used to determine the weight of each evaluation parameter, and on this basis, groundwater quality evaluation was carried out, and the spatial distribution map of groundwater quality was drawn according to the evaluation results. The results show that the weight values of the five parameters of NO2–, Fe, As, Cr6+, and NO2–N are more than 0.1 among the total of fifteen parameters, and the concentration of these five parameters can be considered as the main influencing parameters of groundwater quality. The calculation results of the entropy weighted water quality index (EWQI) show that all the groundwater quality in the study area is class 1 water, which is Excellent Water. However, the EWQI value is the highest in the southwest of the study area, showing a trend of deterioration of groundwater water quality. Since all groundwater samples were evaluated as “excellent water,” it was speculated that the natural environment had more influence on groundwater chemical characteristics than human factors. The study found that 7.407% and 55.556% of the water samples posed a noncarcinogenic health risk to adults and children, respectively. The main responsible parameters for noncarcinogenic risk are F−, NO2−, NO3−, and Cr6+. The carcinogenic risk for adults ranged from 0 to 6.91E-04, with a mean of 1.00E-04. The carcinogenic risk for children ranged from 0 to 1.03E-03, with a mean of 1.55E-04. These toxic elements are mainly from industries. Therefore, the deterioration of groundwater quality can be prevented by strengthening the sewage management of various industries.
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