Abstract: In order to solve the problem of combined pollution of surface water and groundwater caused by industrial residual gangue and steel slag open-air solid waste yard in the area along the Yangtze River in Ma’anshan City，Anhui Province，aiming at the current situation of unclear pollution mechanism of regional solid waste and lack of basis for water environment control，the mechanism of pollutant migra⁃ tion and diffusion is studied. Taking the surface water and groundwater of the tributaries along the Yangtze River during the wet season as the research object，the multi-index laboratory quantitative detection meth⁃ od is used to systematically analyze the spatial distribution of water quality and pollutant migration charac⁃ teristics of surface water，shallow phreatic water and underlying aquifuge in combination with regional geo⁃ logical conditions. The results show that rainwater surface erosion and rainfall infiltration runoff are the main migration pathways of pollutants. The core endogenous pollution is the high alkaline wastewater pro⁃ duced by the leaching of solid waste CaO，and the secondary exogenous pollution is the ammonia nitrogen input from the extraterritorial agricultural non-point source. The concentration of pollutants gradually de⁃ creases from the center of the solid waste pile to the outside，and drops sharply near the river channel. The runoff process of surface water and groundwater determines the spatial gradient distribution of regional pH value. The two-way hydraulic exchange between surface water and groundwater in wet and dry seasons leads to seasonal differences in water dilution capacity. The dilution performance of the aquiclude is poor，and the risk of alkaline pollution retention is higher. The research results can provide measured data and mechanism support for the coordinated control of water and soil in solid waste dumps along the Yangtze River and the improvement of regional water environment carrying capacity.

Key words: surface water, groundwater, pollutant migration and diffusion, Yangtze River coastal area