Hydro-chemistry Characteristics And Cause Of The Zengpiyan Groundwater In Guilin

Groundwater is one of the major sources of fresh water in the world,because of the relatively abundance and excellent quality,the karst groundwater has been considered as an important source of water supply,especially in the karst area of southwest China.Groundwater not only can be used as the water-supply source of the lives of residents,but also the water-supply source of the industry and agriculture,so groundwater have a great importance for human life and production.Human usually concern the economic development but ignore the environment development.The quality of Groundwater is suffering the pollution of human life and production constantly.The karst system act as a fragile ecosystem,which developed broadly,because of the two-tier structure of the earth surface and subsurface,thin layer,which lead the bedrock widely become bareness.Because of the lack of the protection of the soil,a lot of the earth surface and air pollutants through the ponor,cenote,funnel,subside,corrosion cracks and other passageway into the karst groundwater systems.Karst area is restricted by environment,unmerited land utilization can lead the karst environment unbalance.And the change of karst groundwater hydrochemistry component and the pollution is the most serious question.The water quality safety problem which caused by the water pollution has seriously affected the people’s quality of life and the development of social economy.To make use of the combination of sulfur isotope tracer in the groundwater pollution source of sulfate,raise the scientific nature of the results.Which can solve the repetition of the single δ34SSO₄ results.This article based on the groundwater of Zengpiyan area as the research object,the method of sulfur isotope and traditional hydrochemistry,analysis the material composition and the change of groundwater hydrochemistry.And to analysis the degradation,absorption,adsorption rule and the durability of the SO₄^2-pollutants in the research area groundwater.According to the result of sulfur isotope data analysis of sulfur pollution source in the study area,Through data analysis,and finally making the following conclusions:The groundwater is mainly characterized by HCO3-Ca and HCO3-Ca+Mg chemical composition,and in different month it also characterized by HCO3+SO₄-Ca+Mg,HCO3 +SO₄-Ca chemical composition.The groundwater is mainly characterized by HCO3+SO₄-Ca+Mg in 2014.Ca2+、Mg2+、HCO3-mainly comes from the Rongxian Formation limesone and Guilin Formation dolomite limestone.These there ions are closely linked with karstification.The hydrochemistrycharacteristics reflect the weathering of carbonate rock dissolution mainly controls the regional groundwater composition.At the same time,the relatively high SO₄^2-reflecting the groundwater maybe affected by human activities.Influenced by monsoon climate,rainfall concentrated,ion concentration in groundwater to reduce the rainy season,dry season,compared to the winter,summer ions under different degree of dilution effect.Due to the anisotropy of the karst system and the high sensitive of the karst water,The hydrodynamic condition of karst water and geochemical environment is different,also can form curve of water chemical differences,mainly for dilution effect and pollutants leaching effect.Pollutant persistent effect can express from the decay rate and the decay speed.The maximum value of the decay rate is Na+ of the kation.The content of K+ in karst mainly resents the rising trend in cavern water and pipe water,the attenuation rate is 20%³5%,mostly only present attenuation in Y3,Ca2+ and Mg+ has no obvious regularity.The decay rate of Cl-in anionic is bigger,mostly is20%⁶0%,The range of the SO₄^2-and NO3-of the fissure water is greater than the pipe water.The decay rate of the SO₄^2-of the cavern water and pipe water is very low and the rate is positive,the change range is very large of fissure water.Except the zk14 has increased,the delay rate NO3-in cavern water and pipe water is similarly,which is 20%³0%,the delay rate of fissure water is higer than cavern water and pipe water.The delay speed of the main runoff is different in different segment and wet season and dry season.The largest range speed of SO₄^2-in kation is Ca2+,the slowest speed is K+,SO₄^2-has a bigger change in the wet season,SO₄^2-mainly shows the negative speed from upstream to downstream,and shows positive speed in dry season.The δ³⁴SSO₄ is ranged from-4.14‰ to 8.13‰ in Zengpiyan area groundwater,the average data is-0.91‰,except the zk10 is positive notably,other sampling points distribution is concentrated,δ18OSO₄ is ranged from-3.25‰ to 9.74‰,excepted the zk10,zk16,y1,other sampling points distribution is concentrated.Use the main probably end member for sulfate to project,which we can see that theδ34SSO₄ andδ18OSO₄ of the surface water and groundwater in Zengpiyan is mainly focus on the atmospheric precipitation and the product from the inorganic sulfur oxidation.Which is agree with the judge before.That state the sulphate of the Zengpiyan groundwater is come from the atmospheric precipitation,soil sulfate and cinder,and the contribution of the soil sulfate has a small amount.