Water-rock interactions and inverse geochemical modeling in a porous aquifer at Jinzhong basin, Northern China

Author(s):  
Q Guo ◽  
Y Wang
2019 ◽  
Vol 98 ◽  
pp. 09004
Author(s):  
Zeyong Chi ◽  
Xianjun Xie ◽  
Yanxin Wang

Datong Basin is a typical groundwater irrigation area in northern China contaminated by As. In order to reveal the distribution of As and the adsorption behavior of As(V) onto topsoil in the Datong Basin, a total of 40 topsoil core samples were collected from a 2 m core. Samples were used for chemical composition analysis and an isothermal adsorption experiment. Results show that the collected samples are not contaminated. The adsorption capacity (Stot value) of topsoil for As(V) at the study site ranged from 257 to 1027 nmol/g with an average of 505.2 ± 200.2 nmol/g. Vertically, both Stot value and topsoil components exhibit a vertical zoning with a positive correlation between the Stot value and K2O, CaO, MgO, Al2O3, Fe2O3 contents while Na2O and SiO2 are inversely correlated. Fe2O3 content shows a strong positive correlation with As content while Al2O3 does not. Moreover, the correlation between Stot value and Al2O3 is much better than Fe2O3. These results indicate that Fe minerals are the main reservoirs of As in the natural topsoil at the study site. Furthermore, both Fe minerals and clay minerals can adsorb As(V), but clay minerals have a greater storage potential. This result indicate that a combined effect of Fe minerals and clay minerals for As(V) accumulation onto topsoil should be considered during geochemical modeling and further agricultural management.


2011 ◽  
Vol 8 (3) ◽  
pp. 1164-1173 ◽  
Author(s):  
Li Peiyue ◽  
Qian Hui ◽  
Wu Jianhua

Inverse geochemical modeling was used in this paper to quantitatively study the formation mechanisms of groundwater in Pengyang County, China. An improved TOPSIS method based on entropy weight was used to perform groundwater quality assessment in this area. The assessment results show that the groundwater in the study area is fit for human consumption and the high concentrations of some elements can be attributed to the strong water-rock interactions. The inverse geochemical modeling reveals that the dominant reactions in different parts of the study area are different. In the south part of the study area, the precipitation of sodium montmorillonite, calcite and the dissolution of gypsum, fluorite, halite, albite and dolomite as well as CO2dissolution and cation exchange are the major water-rock interactions, while in the north part, the leading reactions are the precipitation of gypsum, dolomite, sodium montmorillonite, fluorite, the dissolution of calcite and albite and the CO2emission and cation exchange are also important. All these reactions are influenced by the initial aquatic environment and hydrodynamic conditions of the flow path.


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