Study Of Poyang Lake Water Environment Carrying Capacity And Pollution Management Mechanism

Poyang lake is the major lake in Jiangxi province, it is also the largest lake in the middle and lower reaches of the yangtze river. The water environment of Poyang lake has great impact on ecological security to the lake area and even the wohle middle and lower reaches of the yangtze river.This article set the Poyang lake as research object, based on analyzing the way of pollution into the lake and caculating the water environment volume, to confirm the carrying capacity of lake water environment to the pollution emission of the lake area. Through analyzing the pollution carrying capacity of major estuary in Poyang lake, to reduce pollution emission for the purpose of protecting water environment, which will certainly have great strategic significance on achieving the Green Rise, Green Development of the province, even on the sustainable development of middle and lower reaches of the yangtze river.The major research content of this article is:(1) Based on the major way for the pollution into the lake, to find out the major pollution sources and polluted areas. The major way for the pollution into the lake is surface runoff, sediment release and rainfall. Among the surface runoff, the five main rivers are the major means, which carry 96% of the total TN and TP into the lake. The Gan River, Xin River and Le'an River, carry the a majority of pollutants in the fiver main rivers, and carrying amount of Xiu River is the least. Gan river basin is the most broad basin, with large population, agriculture and industry are well developed, which make the Gan River is the largest pollution emission source, and result in the most polluted cross-sections in Gan River. In fact, almost all the polluted cross-sections are caused by industrial wastewater discharge. Some seriously nitrogen and phosphorus polluted sections in Rao River can be ascribe to the rapid economic development in Rao River valley. Xin River's high TP concentration aslo can be asribe to the phosphate companies lied along the upper reaches of the Xin River. Soil erosion is another major source of pollutants, which causes a large amounts of sediment with nitrogen and phosphorus into the lake. Therefore, the estuary of the five main rivers should be treated as a key control areas, and the Gan River, Le'an River and Xin River should be the top priority.(2) According to the distribution of major pollution sources and water environment features of the lake, to confirm the water diffusion model of different subarea and plan the pollution carrying capacity of lake water environment. In the year 2007 and 2008, the TP, COD_Cr and NH3-N water environment carrying capacity were 166729.3 and 155798.1t/a, 433642.06 and 648401.48 t/a, -15718.24 and 1818.49 t/a respectively. TP and COD_Cr capacity values were all the positive number, but the NH3-N capacity of Poyang lake was very small, especially in 2007, it was negative, which means it can bear no more NH3-N emission.(3)To analyze the pollution carrying capacity of Poyang lake, set the water environment volume as the restricted value, brought up the the pollution abatement area and total amount of Poyang lake.There is plenty of room for TP carrying capacity of Poyang lake, the COD_Cr carrying capacity is closed to saturation, the remaining capacity of the environment is not too much. The NH3-N carrying capacity of Poyang lake is far less than the pollution emission, which is affected by the negative capacity of Gan river and Le'an river. So it is urgent to cut down the NH3-N emission.(4)In order to control the eutrophication process of Poyang lake, improve water quality, this article advocates to improve the management of Poyang lake, implement the total amount control of pollution, implement theh total control responsibility, strictly control the sewage outfall into river and lake, carry out the sound policies and regulations on publicity, education and social participation, brought up the pollution control measures such as surface runoff pollution control,soil and water conservation and sediment release control, suggests to increase R&D investment, build monitoring system, lay the foundation for achieving Green recycling economy and a good ecological beauty of "a lake of clear water".The analyses on the major way for the pollution into the lake and environment volume provided the basis for achieving total control of pollutants, established a solid foundation for achiving "a lake of clear water" and promoting the rapid and harmonious development of economic and social.