Quantitative Analysis And Policy Study On The Sources Of Marine Plastic Waste In Xiamen Bay

Marine debris pollution particularly microplastics is becoming a serious problem and has attracted wide attention on the global scale.Recently,most studies focuses on the quantity or density of marine debris in the environment and the adverse effects on the ecosystem and the society.However,there are few studies about the quantitative and policy analysis of the sources of marine debris pollution.If the sources of marine debris emission is taken into consideration,the effort in prevention and control of marine debris will be carried out more effective.With regards to the above issues,the quantitative analysis and the policy simulation of marine plastic waste were developed from different sources in this study,which can provide policy recommendations for the prevention and control of marine plastic waste pollution.For quantitative analysis,we established a comprehensive quantitative system of marine plastic waste from different sources,including the following four aspects based on the estimation of the plastic waste output:(1)From river to the sea based on the parameters of coastal population,management level of domestic waste and hydrolog:ical conditions of the basin.(2)From marine aquaculture,based on the parameters of aquaculture area,fishing tools usage,replacement rate and the ratio of waste into the sea.(3)From coastal tourism activities,based on the number of tourists,the rate of waste production,the ratio of waste into the sea and other parameters.(4)Microplastics from sewage outlets into the sea,based on the amount of effluent and its concentration.In this study,Xiamen Bay is taken as the study area,including Weitou Bay of Quanzhou,sea area under the jurisdiction of Nan'an and Xiamen city,and the Jiulong river estuary area involved in Zhangzhou and Longhai city.The results showed that:(1)Around 97.79 tons of plastic waste entered the sea through Jiulong river basin in 2017 if there is no interception,collection or cleanup action in the river.(2)Before the implementation of the new aquaculture planning,the annual emission of plastic waste generated in the process of shellfish aquaculture and cage aquaculture in the neritic zone of Xiamen Bay in 2017 was about 385.29 tons and 52.85 tons respectively,which amounts to 438.14 tons in total.(3)About 566.80 tons of plastic waste entered into the sea due to coastal tourism activities in 2017.(4)About 1.866× 1011 microplastic particles were discharged into Xiamen Bay sea area through the sewage treatment plants in Xiamen,Zhangzhou,Longhai and Jinjiang in 2017,with an average mass of 559.78 tons,ranging from 373.18 to 764.37 tons.Therefore,coastal tourism is the largest pollution source of marine plastic waste in Xiamen Bay,which accounted for 34.09%of the total emission.The discharge of microplastics from the sewage treatment plants and the emission of plastic waste from marine aquaculture both represents a significant proportion,which accounted for 33.67%and 26.36%respectively.These three sources above are considered as the main pollutant sources of plastic waste in Xiamen Bay,while the rivers(Jiulong river basin)caused the minimum output of plastic waste,which only accounted for 5.88%.In the policy analysis for prevention and control of marine plastic waste,we developed a quantitative model of marine plastic waste from different sources based on the system dynamics method.The quantitative results under different policy scenarios were simulated by the model.We set up five scenario simulations under different policy effects,including strengthening coastal waste management,reducing production and emission of plastics,promoting technological innovation,enhancing fishery management,and comprehensive management and control.The simulation results showed that the policy of comprehensive management and control has a significant effect on the reduction of plastic waste in Xiamen Bay,with the total emission reduced to one-third of the original value.In the scenarios that implemented single policy,technological innovation made the greatest effort in the reduction of plastic waste,leading to the discharge of microplastics from sewage and the emission of foam plastics from neritic shellfish aquaculture decreased by more than half.But the impact of enhancing fisheries management on emissions reduction was not obvious,which is mainly related to the actual situation of the study area.Finally,we put forward the following policy suggestions for the prevention and control of marine plastic waste:(1)controlling the waste from sources,and strengthening the level of waste management,(2)promotion of technological innovations,and reducing of plastic production and emissions,(3)collecting and cleaning up of marine waste with particular attention to microplastics,and(4)enhancing publicity and education,while raising public awareness of environmental protection.The results of this study,quantitative and policy analysis on marine plastic waste,makes for a direct comparison of the emissions from different sources.It would be beneficial for the government to formulate corresponding policies and carry out the work of prevention and control in marine plastic pollution from different sources more effectively.