The Observation Of Generation And Dissipation Process And Study On Pollution Characteristics Of Haze In Fuzhou Area

Fuzhou is an important city in the southeast coast of China,which location on the Western Coast of Taiwan Strait(WCTS).The social economy is developed rapidly,but the economic development also accompanied by a certain degree of air pollution.When the haze events frequently happened around the country,the haze in Fuzhou is also increasing.The air quality is decreased gradually in Fuzhou,which not only brings inconvenience to people’s life and causes certain harm to the health of the residents,also has a negative impact on the construction of ecological civilization demonstration area of Fujian province.In order to sostenuto bulid a propaganda name card of "blue Fuzhou",it has an important practical significance to observe the haze’s generation and dissipation process in Fuzhou,and summarize its pollution characteristics.What’s more,our study can also provide a reference for the government and relevant departments in environmental decision-making.The study combined with the regional joint observation,sampling analysis and other assistant method to identify the two typical types of haze in Fuzhou area:transmission and accumulation.In this paper,the mechanism of the formation and dissipation of these two types haze were discussed,the characteristic variety of meteorological factors and pollutants in haze pollution process were analyzed,the function of the meteorological conditions were investigated,the contribution of the chemical composition of pollutants to the formation of haze was distinguished,and the pollution characteristics and causes of different types of haze components were explored.Based on the analyses of the generation,dissipation and pollution characteristics of transmitted haze pollution and accumulated haze pollution in Fuzhou area,we found that the transmitted haze pollution occurred in winter,mainly the Yangtze River Delta pollutants transmitted through the coastline of the transmission process channel,and Zhejiang province and Ningde city were the main pollutant sources(49.98%).The whole process were accompanied with continuous cooling(10.2 ℃ to 7.2 ℃),boost(1015 hPa to 1017 hPa),humidification(72%to 81%).The transmitted haze pollution dissipated mainly by the clean sea air’s dilution and rainfall erosion’s removal of pollutants.The accumulated haze pollution was mainly caused by the early accumulation of biomass burning and dust input,which occurred in the spring and lead the local pollutant hard to spread and raise continuously under the low wind speed(1m/s),high temperature(18 ℃),high humidity(73%)and other adverse weather conditions,bringing about 99.68%local contribute.The dissipation was mainly caused by the late occurrence of rainfall event washing away the pollutants.The daily average concentration of PM2.5,visibility and the relative humidity of transmitted haze pollution were 88.50 μg/m3，3.8 km,and the results of accumulated haze pollution were 73%and 76.11 μg/m3,7.3 km,73%,in respectively.The particle number concentration and mass concentration in the generation phase of the two types of haze increased significantly.The partial size was concentrated in the accumulation mode(1～2.2 μm),the concentration of each component,especially the secondary water soluble ions increased;SA/PM2.5 reached to 72%;NOR and SOR were 2.46 and 1.26 times in winter,1.56 times and 1.34 times in spring,respectively,then the transformation degree of NO2 was more obvious.The accumulated haze particle size(1.5-2.2 μm)is larger than the transmitted type(1-1.5 μm),while the generation of secondary aerosol(about 36%)was lower than that of the transmitted type(about 60%).The pollutants were transported by long distance,which was mainly fine particles in the transmitted haze,and major ions changed form NO3’(37.85%)to SO4 2-(40.19%).Due to the influence of foreign sand and dust input and biomass combustion in the accumulated haze prophase,the pollution was mainly coarse particle pollution,PM2.5/PM10 ratio was in the range from 42%to 63%,the proportions of Ca2+,Na+ and K+ were7.22%in the coarse particle pollution,which was larger than the 2.57%in the fine particle pollution.The accumulated haze late converted to fine particle pollution,PM2.5/PM10 ratio in the range from 62%to 98%,while NO3-increased from 28.42%to 38.44%.