Impact Of Ship Emissions On Air Quality And Its Uncertainty Analysis Over Chinese Waters In 2013

In recent years,the air pollution in China improving gradually,but still higher than the national secondary air quality standard,the American standard and the WHO limits.The situation of air pollution control is still severe.Ship emission is one of the major contributors to the anthropogenic emissions in China,shows obviously impacts on air quality and human health.Aggravating the air pollution in the ports and the surrounding areas,as one of the key problems of governance.Accurately quantified the air quality impact of marine air pollutants is the basic basis of ship emission control measures formulating.Previous studies had developed several sets of ship emissions in China but none of them quantified the impacts.In this paper,based on an air quality simulation platform?WRF-SMOKE-CMAQ?and AIS-based ship emissions in 2013,we used the Brute-force method?BFM?to quantify the impact of ship emissions on air quality in coastal areas of China.The pollution data from more than 700 sites published by the China monitoring station and the data of the OMI satellite's pollutant concentration are verified and the air quality simulation platform is optimized.Secondly,the impact of ship emissions on air quality in coastal areas is simulated and analyzed by sensitivity analysis.Furthermore,quantitative evaluation of ship emission uncertainty and its impact on simulation results is made.Finally,this papar integrate the latest international ship emission control measures,set up the scenario of ship emission control,and conduct simulation evaluation of emission reduction effect under control scenario.The results are as follows:The temporal variation of impacts and its key driving factors were also investigated.Results show that 5%(1.1?g·m^-3)of SO₂ concentrations,7%(1.7?g·m^-3)of NO₂ concentrations and 2%(0.9?g·m^-3)of PM_2.5 concentrations in coastal provinces can be attributed to ship emissions.Particularly,these contributions increase in the Yangtze River Delta?YRD?and the Pearl River Delta?PRD?region,such as 14%,13%,4%in YRD,and 30%,31%,8%in PRD.The seasonal variation of impacts on air quality is obvious,especially in terms of the spatial distribution of PM_2.5 concentrations.In the three urban agglomerations,the maximum difference among seasons can reach 1.3² for SO₂,1.2⁴ for NO₂ and 1.8⁷.5for PM_2.5.The impact on PM_2.5 and O₃ formation is obviously regional and temporally complex.On the whole,the contribution concentration of pollutants in spring and summer is higher than that in autumn and winter,and the regional seasonal climate change?the decrease of atmospheric activity in autumn and winter?is the key factor.Under different background concentrations and meteorological conditions,the contribution of ship emission to PM_2.5concentration shows a significant regional?long distance transmission?and compound?two generation?,but it promotes the formation and consumption of O₃.The uncertainty of SO₂,NOx and PM_2.5 in the total emission inventory uncertainty is about-6.3%⁸.6%,-5.9%⁸.6%,and-8.4%13.5%,respectively,in the uncertainty of the simulation results caused by the uncertainty of total emission to 1%¹1%?in three regions?,generally lower than their own uncertainty.The influence of the time and space assignment uncertainty on the emission of a single grid?27 km×27km?is±5000 tons,which causes the the uncertainty range of SO₂?±13%?,NOx?±8%?and PM_2.5?±3%?of the simulated concentration of the three large urban agglomeration.It can be seen from this,that the influence degree of the spatio-temporal distribution of ship emissions on the simulation results is greater than that of the total emission of ships,and the regional differences and species differences are all larger.In addition,the OMI satellite NO₂ concentration data and the concentration of the coastal monitoring site PM_2.5 were used to evaluate the simulated concentration of three sets of space-time distribution schemes.The results of satellite inversion concentration check show that the correlation of space-time distribution based on ship type is the strongest with the satellite inversion concentration,the correlation coefficient R² is 0.793,and the result of monitoring concentration evaluation indicates that the average deviation of the ship type scheme standardization is also the smallest?-13.9%?.The processing method of time and space distribution is more reasonable.According to the development trend of international shipping trade and the level of China's ship emission control,it is expected that the level of China's ship emission will still rise in 2020and 2025,but it can be effectively reduced under the action of related emission control scenarios.The assessment of the effect of emission reduction shows that the expansion of China's Marine emission control area in the next stage can include more ports along the 12-nautical mile range on the basis of the existing DECAs.In the future,strengthening NO_X control can achieve better emission reduction effect.It is recommended to pay attention to NO_X emission reduction.