The Study On Migration And Transformation Of Agricultural Non-point Source Pollutants In Typical Areas Of Haihe River Basin

Haihe plain is the main agricultural area in North China,groundwater is the most important source of water for the Haihe River Basin.However,with the development of the economy and society,the problem of groundwater resources pollution and over-exploitation in the Haihe River Basin has become increasingly serious.At present,it is recognized that non-point source pollution caused by agriculture is one of the biggest problems in water pollution.While the situation of groundwater resources protection is becoming more and more severe.Understanding of non-point source pollution for one of the groundwater sources is extremely important to formulate groundwater environmental protection and governance strategies in the Haihe Plain.For example,the source,composition,spatial distribution characteristics of agricultural non-point sources etc..This study collects information on remote sensing images,land use patterns,hydrogeological conditions,etc.in typical areas.Moreover,the investigation of related agricultural non-point source pollution is carried out;the“3S”technology and the output coefficient method are used to estimate the agricultural non-point source pollution load in the plain area of the Haihe River Basin,and the spatial distribution characteristics and main influencing factors of agricultural non-point source pollution in the typical area are evaluated and analyzed;the HYDRUS-1D model was used to simulate the migration of water,energy and solute in porous media in typical areas.Based on non-point source pollution survey,hydrogeological conditions survey of Haihe River Basin,and one-dimensional numerical simulation results of non-point source pollution,the system analyzes the process and scope of the impact of agricultural non-point source pollution on the groundwater environment in the typical area of the Haihe River Basin.The results show:?1?The pollution discharge load of livestock and poultry breeding in Haihe River Basin accounts for the largest proportion of total agricultural non-point source pollution load.The emissions of COD,NH₃-N,TN and TP accounted for 83.6%,17.5%,55.0%and81.0%of the entire Haihe River Plain,respectively.Therefore,it can be seen that livestock and poultry farming in the plain area of the Haihe River Basin is the most important control factor for non-point source pollution in this basin.?2?According to the discharge intensity results of various provinces,cities and counties?districts?in the Haihe River Basin,the emission intensity of pollutants in the western,southern and eastern areas of the Haihe River Plain is significantly higher than that in the northern and central regions.In this region,the spatial distribution of non-point source pollution emissions is uneven.?3?The typical groundwater in the drinking water of the city is affected by NO^3-,which accounts for 43.47%of the organic matter nitrogen from the soil;the animal manure and sewage nitrogen account for 34.78%;the fertilizer nitrogen accounts for21.75%.?4?In the one-dimensional vertical numerical simulation results of typical areas,the concentration of ammonia nitrogen decreases rapidly after entering the soil layer,and the migration rate is slow and the accumulation phenomenon occurs on the soil surface.The typical area of nitrogen is mainly found in soil layers above 3 m,and is only enriched at more than 5 m.Due to the long-term over-exploitation of groundwater in the plain area of the Haihe River Basin,the groundwater depth in most areas of the central and western regions is>5 m.Therefore,the non-point source pollution is concentrated in the shallower aerated zone soil,which is difficult to directly pollute the groundwater.