The identification of groundwater chemical characteristics and the controlling factors is of major concern in water environment studies. In this study, we identified the groundwater chemical characteristics, evolution laws and main control factors in a region severely affected by human activities using hydrochemical and multivariate statistical techniques. The results showed that the concentrations of NO3− and TH were the primary pollution factors in the region with intensive human activity because of high concentration and over the standard rates. The major types of groundwater chemistry were HCO3·SO4–Ca and HCO3·SO4–Ca·Mg. The sulfate-type water was as high as 75.0%, 69.2% and 41.2% in the three hydrogeological units. In addition, there were Cl-type and Na-type waters, indicating that the groundwater in this area has been significantly affected by human activities. A principal component analysis (PCA) indicated that the three factors affecting groundwater hydrochemistry in the study area are domestic sewage and fertilizer, water–rock interactions and industrial wastewater. Therefore, we suggest that the government and water environment management departments should prevent the discharge of domestic and industrial wastewater without standardized treatment first in order to effectively prevent the further deterioration of groundwater quality in this area.

p-Nitroacetanilide solubility in fifteen neat solvents (N,N-dimethylformamide, ethylene glycol, acetonitrile, methanol, ethyl acetate, n-propanol, ethanol, 1,4dioxane, isopropanol, water, n-butanol, isobutanol, cyclohexane, n-heptanol, and Nmethyl pyrrolidone) was reported. Experiments were done using the shake-flask technique under 101.2 kPa at temperatures ranging from 278.15 to 323.15 K. The solubility magnitudes in the selected 15 neat solvents followed a decreasing trend as Nmethyl pyrrolidone (N,N-dimethylformamide) > 1,4-dioxane > ethyl acetate > n-heptanol > acetonitrile > n-butanol > n-propanol > ethanol > isopropanol > methanol > isobutanol > ethylene glycol > water > cyclohexane. Polymorphic transformation and solvation did not happen in the 15 solvents in the equilibration process. Mathematical correlations of equilibrium solubility were studied using activity coefficient models (NRTL and Wilson), semi-empirical equations (λh equation and Apelblat equation), and a simple multiple linear regression model. The maximum values of root-mean-square deviation and relative average deviation between the experimental solubility data and back-calculated ones were 59.45 × 10 −4 and 3.47%, respectively. The Apelblat model presented a better correlation result than the other models. An inspection of the interactions between the solvent− solvent and solute−solvent molecules was carried out through the linear solvation energy relationships. Moreover, the dissolution thermodynamic properties, reduced excess enthalpy, and infinite dilution activity coefficient were achieved through the Wilson model.

No abstract