| China’s marginal seas include the South China Sea,the East China Sea,the Yellow Sea and the Bohai Sea.They are important economic and trade windows and sources of livelihood for East and Southeast Asian countries.Due to high-intensity human activities along the coast,China’s marginal seas are facing severe pollution and the marine ecosystem has been destroyed.As a result of measures related to carbon neutrality,pollutants related to energy consumption are controlled synergistically,reducing their emissions in the environment.Polycyclic aromatic hydrocarbons(PAHs)are a class of pollutants with great environmental hazards,mainly produced by activities related to energy consumption,and have destructive risks to marine ecosystems.Therefore,it is of great significance to understand the ecological risks of China’s marginal seas under the carbon-neutral scenario of PAHs emissions from East and Southeast Asia.This study uses a neural network-based chemical transport model to assess the ecological risk of anthropogenic polycyclic aromatic hydrocarbons to marine ecosystems under a carbonneutral scenario.Through the bottom-up method,using satellite data and energy ladder model,establish the latest high-resolution polycyclic aromatic hydrocarbon emission inventory,and obtain the emission law and spatio-temporal characteristics of PAHs in the study area;use enhanced regression tree model and multiple regression model,based on shared socioeconomic pathways to establish PAH emission forecasts under carbonneutral scenarios.Through the chemical transport model,the concentration distribution of polycyclic aromatic hydrocarbons in China’s marginal seas was established,and the occurrence of polycyclic aromatic hydrocarbons in the sea area was predicted under the carbon neutral scenario.Finally,the ecological risk of polycyclic aromatic hydrocarbons to China’s marginal seas was assessed by the Monte Carlo method.(1)The emission inventory shows that there are high-intensity PAHs emissions in the coastal areas of China’s marginal seas.Differences in the level of development among regions lead to the diversity of emission characteristics.Southeast Asian countries have a relatively low level of development,and their PAHs emissions are mainly from agriculture-related incineration activities and household energy consumption.China’s economy has developed rapidly in recent years,so the proportion of industrial sources and transportation sources is higher than that of other countries,while the content of polycyclic aromatic hydrocarbons produced by agricultural activities and household energy consumption has been declining in recent years.High-income countries and regions show a trend of decoupling PAHs emissions from economic levels,with low levels of PAHs emissions.(2)The population,GDP and urbanization level are important factors affecting PAHs emissions.For low-income countries,such as Southeast Asian countries,the level of PAHs emissions will increase significantly in the future.For middle-income countries,such as China,PAHs emission levels will rise slowly,reach a peak level in 2030,and then decline.For high-income countries,the emission levels of PAHs show a basically flat or declining trend.The forecast based on the carbon neutral scenario of sustainable development shows that the overall PAH emission level in East and Southeast Asia shows a downward trend.(3)The numerical simulation results of the chemical transport model show that there are high concentrations of marine PAHs pollution in the Bohai Sea and the Yangtze River Estuary.The rapid economic development of various regions in the region has led to a rapid increase in the concentration of polycyclic aromatic hydrocarbons in seawater in the past 20 years,and maintained a high concentration level.Using the sustainable development scenario of shared socio-economic pathways to predict future PAHs emissions,the results show that the implementation of carbon-neutral policies has the potential to effectively reduce PAHs emissions in the region,and ultimately promote the multi-cyclic aromatic hydrocarbons in China’s marginal seas.Reduced occurrence of ring aromatics.(4)The risk assessment model shows that with the decrease of PAHs emission level,the overall ecological risk in China’s marginal seas will decrease accordingly,and the ecological risk level presents a spatial pattern of successively decreasing in Bohai Sea,Yellow Sea,East China Sea,and South China Sea.The reduction of PAHs emissions under the carbon-neutral scenario has effectively improved the population decline risk and consumption risk of small yellow croakers.The ecological pressure of the population indirectly promoted the recovery and growth of the small yellow croaker population.At the same time,the health risks caused by human consumption of small yellow croaker were reduced by 56%-81%.But it is still necessary to take measures to further control the release of PAHs to the environment. |
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