| Clean air environment and its potential change over the Yunnan Plateau is an issue for further study on atmospheric environment.In this paper,we use the air pollutant concentration data monitored from 2014 to 2018 to analyze the seasonal variation of air pollution in Kunming and the interaction between PM2.5.5 and O3.The atmospheric environmental capacities of CO,NOx,SO2,PM2.5.5 and PM100 in Yuxi are estimated based on WRF-Chem by applying an iterative algorithm for assessing the atmospheric environmental capacity governed by air quality targets according to the national ambient air quality standards?GB3095-2012?.A moderate pollution process in Kunming from March 21st to22nd,2015 is selected and WRF-Chem is used to conduct a simulation experiment on the sensitivity of the biomass burning emission in Southeast Asia.The trans-boundary transport of pollutants from the biomass burning emission and its impact on PM2.5.5 concentrations in Yunnan Plateau is explored,under the background of the prevailing southwest wind.The following conclusions were obtained:1.The seasonal variation of air pollution in Kunming and the interaction between PM2.5and O3From 2014 to 2018,the annual average concentrations of SO2,NO2,PM10,PM2.5.5 and CO in Kunming showed a downward trend,while O3 increased.The seasonal changes of PM10,PM2.5.5 and PM2.5-10.5-10 were basically the same,showing the highest in winter and the lowest in summer,while O3 was high in spring and low in autumn and winter.The pollution frequency of PM2.5,PM100 and O3 in Kunming was 0.54%,1.49%and 0.72%,respectively,which were much lower than those in the eastern region of China.The diurnal variation trends of PM2.5,PM100 and PM2.5-10.5-10 in four seasons are basically the same which show a double peak curve,and the two peaks occur around 9:00 and 0:00.Fine particles dominated atmospheric particles in all seasons and annual mean ratio of PM2.5/PM100 was 0.59.O3dominated atmospheric oxidation OX?NO2+O3?,contributing about 63%.The higher the OX concentration in the atmosphere,the higher the secondary PM2.5.5 concentration;the increase of O3 in spring promotes the formation of PM2.5,and the high concentration of PM2.5 in winter inhibits the formation of O3.2.An elaborative assessment of atmospheric environmental capacity in Yuxi based on WRF-Chem modelingThis study is focused on Yuxi,an important industrial area over the plateau.The estimation of atmospheric environmental capacity is conducted based on the meso-scale air quality model WRF-Chem in a fine resolution of 3 km.Based on the simulation of major air pollutants for winter,spring,summer and autumn in 2015,and by applying an iterative algorithm for assessing the atmospheric environmental capacity governed by air quality targets according to the national ambient air quality standards?GB3095-2012?,the atmospheric environmental capacities of primary PM10,primary PM2.5,SO2,NOx and CO emissions in Yuxi are estimated with 1.284×104 t·a-1,0.854×104 t·a-1,1.917×104 t·a-1,1.796×104 t·a-11 and 51.556×104 t·a-1,respectively.The seasonal variations of atmospheric environmental capacities in the entire and urban areas over Yuxi are characterized with troughs in winter and peaks in spring for the major air pollutants excepting for PM2.5.The remaining atmospheric environmental capacity in the urban area accounted for 40%of that in entire Yuxi region,reflecting the regional differences in atmospheric environment and possible environmental change resulted from the industrial development and urbanization over this plateau region.3.The trans-boundary transport of pollutants from the biomass burning emission and its impact on PM2.5.5 concentrations in Yunnan PlateauIn the process of pollution in March 2015,under the influence of prevailing winds in southwest China,the PM2.5 pollution incident in Yunnan Province was mainly affected by the trans-boundary transport of atmospheric pollutants emitted from the biomass burning emission in Southeast Asia and the contribution was up to 67.18%.The main three-dimensional transport path?transport channel?of PM2.5.5 trans-boundary transport is:horizontally from Xishuangbanna in the southwest to Kunming in the northeast,the vertical height is about 380m above the ground at the border and about 1320m above the ground in Kunming. |
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