| In the past 30 years of reform and opening up in China, with the rapid development of society and economy of the Bohai Rim Region, more and more pollutants have been discharged into Bohai Sea, thus it leads to deteriorating seawater quality. However, the original concentration control and target total emission control systems are unable to meet the demand of modern management of the marine environment. The implementation of capacity total emission control of pollutants is an important and effective measure to improve marine water quality. The capacity total emission control contains estimation of pollutant fluxes into the sea, calculation of marine environmental capacity and allocated capacity, optimization and allocation of capacity. The pollutant flux estimation is the base, and the calculation, allocation and optimization of capacity is the key of the research.Aimed at the optimization and allocation of capacity, a forefront and hotspot of this field, the research is carried out based on the study of marine environmental capacity and allocated capacity. The allowable emission capacities of chemical oxygen demand (COD) and dissolved inorganic nitrogen (DIN) are calculated according to the principle of multi-target nonlinear programming and the scheme of total emission control is proposed, meanwhile, the industrial and industry structure is optimized and adjusted. The methods and results of research are showed as follows:(1) Various pollution sources of Bohai Sea are summarized and analyzed, the principle and method of estimating the pollutant fluxes into the sea are established, and the law of annual fluxes of COD, petroleum hydrocarbons, nutrients, heavy metals and other pollutants into Bohai Sea from 1979 to 2005 is obtained. The results show that the COD flux from 13 coastal cities presents an inverted U-shape with an average flux of 1,500 thousand t/a, the petroleum hydrocarbons flux presents an inverted N-shape with an average flux of 150 thousand t/a, the DIN flux presents an N-shape with an average flux of 15 thousand t/a. The annual fluxes of total dissolved phosphorus (TDP), volatile phenol, Hg, Cd, Pb, As, Cyanide, suspended solids(SS) are 20 000 t/a, 300 t/a, 30 t/a, 400 t/a, 1 400 t/a 2 000 t/a, 800 t/a, 4800 000 t/a, respectively.(2) The sources of various pollutants are analyzed and the results show that rivers are the primary pollution source, the sea is an important source for petroleum hydrocarbons, sewage outfalls are also an important source for DIN, TDP, COD, Hg and volatile phenol. The role of atmospheric deposition can not be ignored for COD and Pb pollution. The percentages of various pollutants in 13 cities are different. On the whole, the pollutants in Bohai Sea mainly come from Dongying, Yingkou, Panjin, Tangshan, Tianjin, and Weifang.(3) The concept of allowable emission capacity is defied and the principle and method of estimating the allowable emission capacity of pollutants in 13 different cities are established. According to multi-objective nonlinear programming, the objective function of the model is the maximization of marine capacity, allocated capacity and emission capacity, and the model constrains contain economic growth, population growth, pollutant emission intensity, environmental investment, and so on. The optimal results show that 13 cities except Qinhuangdao and Tangshan should reduce their discharge of COD under Gradeâ… of the National Seawater Quality Standards (NSQS),, the largest reduced quantity of Yingkou is 73 000 t/a, and the least reduced quantity of Cangzhou is 12 000 t/a. As for the reduced rate, Panjin is the largest and Weifang is the least. Under Gradeâ… of NSQS, the discharge of DIN also should be reduced in 13 cities, the largest reduced quantity of Tianjin is 21 100 t/a, and the least reduced quantity of Yantai is 1 600 t/a. The reduced rate of 86% in Yingkou is the largest and the reduced rate in Tangshan is the least.(4) The model of multi-objective nonlinear programming is established based on the objective function of maximizing different industrial sectors'emission capacity, and the constraints of economic growth, industrial structure proportion, pollutant emission intensity. The results show that the discharge of COD in all industrial sectors in Tianjin should be reduced in 2010 under Gradeâ… of NSQS. The largest reduced quantity in 13 cities was 20 000 t/a in Industry Sector of the second industry and the reduced quantity in Forestry Sector is the least. Accordingly, the proportion of the first, second and ternary industry is adjusted from 3.0:56.0:41.0 to 2.0:55.6:42.4.(5) The model of multi-objective nonlinear programming is established based on the objective function of maximizing different industry sectors'emission capacity, and the constraints of economic growth, pollutant emission intensity, water consumption, energy consumption, labor productivity. The results show that the allowable emission capacity of Building Material Industry, Medicine Industry, Automotive Industry, Machinery Industry, Telecom Industry, and Environmental Protection Industry exceeds the discharge in base year (2005). The largest surplus allowable emission quantity of 6 industry sectors is 300 t/a in Medicine Industry and Automotive Industry account for the largest percentage. All the remaining industry sectors should reduced their discharge quantity. The largest reduced quantity of COD is14 000 t/a in Paper Industry, and its reduced rate is also the largest. To maximize the allowable emission capacity of industry sectors, Tianjin government should vigorously develop Telecom Industry, Automotive Industry, Medicine Industry and Machinery Industry, properly develop Garment Industry, Building Material Industry, Oil Industry, Chemical Engineering Industry, Environmental Protection Industry, Energy Industry. On the other hand, Textile Industry, Paper Industry, Chemical Industry should be reasonably restricted and Mining Industry, Metallurgical Industry should by strictly restricted.The research work supply necessary theoretical foundation and technical support for the implement of total emission control in coastal waters in China, furthermore, it can direct the ecological environmental governance and the optimization and adjustment of industrial structure of coastal cities.
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