Multi-Isotope Tracing of the Impact of Human Activities on the Hydrological Environment in the Muli Permafrost Region
In order to find out the impact of human activities on the hydrological environment of Muli permafrost area,Juhugeng mining area of Muli Coalfield with the most significant human activities in the alpine permafrost area was selected,and the river water of Datong River tributary system in the area was taken as the research object.Based on the spatial characteristics of hydrochemical composition,the research was carried out by using multiple isotopes such as hydrogen,oxygen,carbon,nitrogen,sulfur and strontium.The results show that:(1)The supra-permafrost water is the main supply source of the river water.Human activities such as coal mining and natural gas hydrate drilling destroy the original frozen soil structure and increase the contribution proportion of the supra-permafrost water to river water;(2)The increase of the concentration of main dissolved nutrients(SO42-,NO3-and DOC)in river water is due to the influence of human activities:sulfur and oxygen isotopes reveal that large-scale open-pit mining in coal mine promotes reduced sulfur oxidation,which is the main reason for the increase of SO42-in the supra-permafrost water and river water;Nitrogen and oxygen isotopes show that the high concentration of NO3-in the river comes from livestock manure of free range grazing;DOC mainly comes from soil organic matter produced by plant degradation in alpine meadow,and there are strong microbial activities in the river water in the source area;(3)Except for H2CO3 weathering carbonate rocks,the weathering of carbonate rock and silicate rock participated by sulfuric acid is enhanced under the influence of human activities and coal mining,which further affects the carbon sink of regional rock weathering.The research results provide research ideas for understanding the evolution of hydrological environment in Alpine permafrost area under the influence of human activities,and provide scientific basis for ecological environment protection in Alpine permafrost area.
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