Stable carbon isotope signatures of high arsenic groundwater and their indicative significancein in Kuitun area of Xinjiang
The stable carbon isotope of groundwater can indicate the influence of organic matter degradation process under the action of microorganisms on arsenic enrichment.Kuitun area of Xinjiang is a typical primary high arsenic water distribution area in the arid region of northwest China.In this study,the groundwater was taken as the research object,and the surface water of Kuitun River was taken as the control.The hydrochemical indicators,dissolved inorganic carbon(DIC),dissolved organic carbon(DOC)and carbon stable isotope of the groundwater were determined and analyzed.The results show that 73％of groundwater in the study area was high arsenic water,with an average value of 60.60 pg·L-1,presenting a reduction-weak alkaline environment,while the surface water was low arsenic water,presenting a neutral and oxidizing environment.The dominant anions in the groundwater were Cl-and Ca2+,respectively.The DIC of the groundwater was commonly influenced by various sources,and the DIC of the surface water mainly came from the influence of carbonate weathering.The value of δ13CDIC ranged from-9.13‰to 0.58 ‰ and the values of δ13CDOC ranged from-21.62 ‰ to-13.79 ‰ in the groundwater.In addition to the degradation of organic matter and the dissolution of carbonate karst under the action of microorganisms,methanogenesis may also affect the δ13CDIC value in the groundwater.There was a negative correlation between δ13CDIC—δ13CDOC and As concentration also between δ13CDIC—δ13CDOC and F e concentration in the groundwater,indicating that microorganisms participated in the reductive dissolution of iron oxides and promoted the enrichment of As.
high arsenic groundwaterstable carbon isotopesdissolved organic carbondissolved inorganic carbon
NETL
NSTL
万方数据
