Method of cost-effectiveness-based total maximum allocated load index and measures of nitrogen and phosphorus pollutants on jurisdictions in Jiangsu coast, China

Abstract

Cost-effective total maximum allocated load (TMAL) management of land-based pollutants is required to promote sustainable and healthy development of coastal areas. For the high concentrations of nitrogen and phosphorus pollutants and the deterioration in water quality in the coastal waters of Jiangsu Province, China, the TMALs of total nitrogen (TN) and total phosphorus (TP) pollutants within jurisdictions were calculated using a cost-efficiency optimization calculation method with a 3D hydrodynamic water quality model. This method is suitable for collaborative pollution prevention and land–sea integration management in coastal areas. Our calculation results showed that the emission TMALs of TN and TP in 43 jurisdictions near the coast of Jiangsu Province were approximately 8.6 × 104 and 0.8 × 104 ton/a, respectively, and the source TMALs were 55.8 × 104 and 14.9 × 104 ton/a, respectively. The high concentrations of nitrogen and phosphorus in these waters were caused mainly by Yancheng, Suqian and Lianyungang City. The average responsibility sharing rates (the responsibility sharing of land-based over-pressured administrative areas to marine pollution areas) of these three cities were 48.3%, 23.4%, and 12.2%, respectively. Regarding over-pressured administrative areas (the administrative regions where the discharge exceeds the allocation capacity), we suggest pollution prevention and technical control measures based on the cost-effectiveness optimization method. First, source control should be strengthened, including the control of industrial point source and agricultural nonpoint source pollution, which account for approximately 77.3% of total reduction. Second, it is necessary to strengthen the construction of the municipal wastewater collection and treatment system, which accounts for approximately 16.3% of total reduction. Further, it is necessary to perform wetland ecological restoration and implement capacity-increasing measures, which account for approximately 6.4% of total reduction. The cost-effectiveness optimization calculation method for the technical indicators of collaborative prevention and control of coastal pollution provides a scientific quantitative basis suitable for global coastal pollution control.