| Mercury is one of the most concerned pollutants in the world.The pollution in the environment has four important characteristics:persistence,mobility,high toxicity and bioaccumulation.The sources of mercury in the environment can be divided into natural sources and man-made sources.Among them,coal-burning emissions have become the main way of man-made sources of mercury.As an important coal production base in Anhui,Huainan is rich in coal resources.The long-term development and utilization of coal resources will lead to land A series of ecological and environmental problems such as subsidence and water and soil pollution.The anthropogenic mercury enters the environment through dry and wet sedimentation.After a series of transformations,it can be directly or indirectly converted into high neurotoxic methyl mercury（Me Hg）and other organic forms,and finally enriched in nutrients through the biological amplification of the food chain.In higher grade fish,it seriously affects the quality of aquatic products and human health.Stable isotope tracing technology has been widely used in the study of the migration and transformation of environmental pollutants and pollution mechanisms.Combining the characteristics of mercury isotope of different environmental samples to study the distribution of mercury in the surface environment of coal mining areas can reveal the mercury content in the surface environment.The distribution characteristics and potential sources provide a scientific basis for the prevention and control of mercury pollution in the complex superficial environment of the study area.This study takes the Guqiao coal mining subsidence area in Huainan as the main research object.By collecting samples of water,soil and water sediments in the study area,the basic physical and chemical properties of the samples and the content of total mercury and methylmercury are tested and analyzed.The mercury in coal mining is discussed.The distribution characteristics in the surface environment of the subsidence area,combined with the physical and chemical properties of different environmental media in the subsidence area,analyzed the factors affecting the distribution of total mercury and methyl mercury in the surface environment of the coal mining subsidence area,and established a multivariate mixed model based on the sample mercury isotope composition,Explore the main source and contribution ratio of mercury in the water sediments in the study area.The main conclusions are as follows:（1）The total mercury content of the soil in the coal mining subsidence area of Guqiao is slightly higher than the soil background value of Huainan city.The total mercury content of the soil in the study area has large spatial distribution differences at different sampling points,which is mainly related to atmospheric emissions and vehicle exhaust emissions from nearby roads.Related;the distribution of methylmercury in the study area is similar to that of total mercury,and the total mercury in the soil has an obvious positive correlation with the content of organic matter and clay.The fine particles rich in organic matter have strong adsorption of mercury;the methylmercury in the soil of the study area Mercury is mainly related to the content of organic matter.Organic matter can promote the methylation process of mercury in the soil under acidic conditions.（2）The average value of the total mercury content in the surface water body of the Guqiao coal mining subsidence area did not exceed China’s surface water environmental quality level IV standard.The total mercury distribution in the water body in the study area showed large spatial differences,and the maximum total mercury content appeared at 11.And sample point14,the long-term contact of coal-fired power plants and coal gangue-filled roads in the subsidence area with water bodies is the main factor affecting the distribution of total mercury in surface water bodies;mercury has a tendency to accumulate toward the surface in water bodies at different depths;water particles in subsidence areas The content of mercury is greater than that of dissolved mercury;the total mercury in the water body is positively correlated with the content of particulate mercury and is mainly composed of particulate mercury,which is mainly affected by man-made mining and aquaculture activities.（3）The total mercury in the water sediments of the Guqiao coal mining subsidence area shows a certain degree of accumulation;the spatial distribution of total mercury and methylmercury content is quite different and the distribution characteristics,transportation,gangue filling and other human activities are water sediments The main reason for the large difference in spatial distribution of mercury in the species;the distribution of Me Hg%is mainly related to fishery and aquaculture activities.The mercury in the sediments of the study area is mainly contained in fine particles of organic matter;methylmercury is positively correlated with total mercury,organic matter,and clay content,Me Hg%is positively correlated with p H,and negatively correlated with clay content.The influence of the particle size composition of the sediment on the methylation process mainly depends on the type of organic matter.（4）The physical precipitation of mercury adsorbed on particles in the water sediments of the Guqiao coal mining subsidence area may be the main reason affecting theδ202Hg in the water sediments.TheΔ199Hg/Δ201Hg in the water sediments of the study area is 0.7304,indicating that the water sediments Part of the mercury undergoes a photoreduction process before it is deposited.The main sources of mercury in water sediments are coal mining and coal burning activities.The average contribution rates of coal,gangue,and soil to mercury in water sediments are 26.54%,38.11%,and 35.34%,respectively.As a stable tracer,mercury isotope can be used to obtain information about the source and biogeochemical cycle. 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