The Study Of Contributing Fators Of Groundwater Salinization In The Middle Of Taiyuan Basin

Taiyuan basin locates in arid and semi-arid climates,and surface water resources are scarce.Massive exploitation and utilization of groundwater has provided important support for the process of economic development and urbanization.With the development of the regional social and economic,the demand for groundwater is increasing.Due to the irrational exploitation and utilization of groundwater resources,a large range of groundwater level landing funnel,groundwater salinization and other environmental geological problems have occurred in the study area,which makes the limited underground fresh water resources more tight,this problem is serious in the middle of the basin.Therefore,in the view of the salinization of groundwater in the study area,this paper,starting with the analysis of hydrogeological conditions and the characteristics of groundwater dynamic field,based on the characteristics of water chemical distribution of groundwater,supported by the environmental isotope method,analyzed the causes of underground water salty in the central area of Taiyuan Basin from several angles.The study shows that the salinity of groundwater in the study area is influenced by the factors such as primary geological environment,groundwater cycle,hydrogeochemical action and human activity,and the formation of shallow salt water is different from that of middle deep salt water.The details are as follows:(1)The formation of salt water in middle deep layer is controlled by primary geological environment.The soluble salts in the primary geological environment control the salt content of the karst water and the deep pore water.The dissolution of soluble salt gypsum in the karst aquifers in the mountain area controls the water quality of karst water,which is Ca-SO₄ type water with high salt content.The karst water supplies pore water in the plain area through the pre mountain fracture zone,thus affecting the salt content of the pore water in the plain area.In addition,the evaporation and concentration of the middle deep aquifers in the plain area have been experienced.The soluble salt content in the pore aquifer is high,and the dissolution of this soluble salt is also one of the reasons for the salinization of the pore water in the middle deep layer.(2)The formation of shallow pore salt water is affected by evaporation condensation,agricultural irrigation and salinized soil.The study area is located in the western arid area,the shallow pore water in the shallow depth of the water level,evaporation and concentration,increasing the salt content of shallow groundwater,and the use of sewage irrigation is another cause of salinization of shallow groundwater;salt in the salinized soil,when the shallow water position fluctuates with the season,it dissolves.The effect also increases the salt content of the groundwater.(3)Groundwater circulation and human activities partly aggravate the salinization of groundwater.From the study of the hydrodynamic field,it is shown that the shallow pore water receives the support of the deep pore water,which causes the shallow groundwater salty in the local area,and the exploitation and utilization of the underground water well is easy to make the salt water supply fresh water.(4)Microbial reduction can slow down the trend of salinization of groundwater to a certain extent,and the SO₄^2-content in water in the medium deep pore water is reduced under the effect of microbial reduction.In this paper,the hydrogeochemical method and environmental isotope tracing method are used to analyze the causes of salinization in the middle of Taiyuan basin from multi angle and multi layer system.The conclusions are complementary and mutually reinforcing.The research results not only have important guiding value for the prevention and control of local groundwater salty and the rational exploitation and utilization of water resources,but also have a certain reference value to the protection of groundwater in other arid areas.