| Aerosol plays an important role in global climate change. The indirect radiative forcing of aerosol is still ofgreat uncertainties.The cloud and its microphysical processesare dependent on the chemical compositopns of aerosol to some degree,therefore it’s particularly important to understand the chemical characteristics of aerosol and cloud.This study examines the chemical characteristics of cloud,the size distribution of water-soluble ions in particles and the chemical characteristics of particles in different heights at Mount Huangshan.The scavenging of aerosol particles by cloud is discussed in this paper.Sampling and monitoring of aerosol and cloud were carried out in summer2009and summer2011. A larger number of samples and data of aerosols and cloud were collected in these fieldexperiments.Results show that the mass concentration spectra of atmospheric aerosol is unimodal and the maximum value locates between0.32μm and0.56μm.The mass concentration of PM10and PM1.8is42.0μg/m3,32.6μg/m3, respectively.The fine particles play a dominant rolein aerosol at mount huangshan.The distribution of SO42-and NH4+is unimodal with the peak locatingbetween0.32μm and0.56μm.The main distribution of NO3-is bimodal.The mass concentration of water-soluble components of aerosol decreases with altitude at Mount Huangshan. The mean mass concentrations of sum of all the ions are13.21μg/m3,10.94μg/m3,9.97μg/m3, respectively,at the foot, mid height and the summit of the mountain, respectively. The major anion and cation of aerosols areSO42-and NH4+. The descending order of mass concentration of major ionic species is:SO42-> NH4+> Ca2+> NO3-.The concentration of SO42-,NH4+K+,Na+,Cl-and Mg2+in PM2.1decrease with altitude. The major cation and anion of coarse mode particles are Ca2+and NO3-, respectively.The concentration of chemical component in coarse mode particles is complicatedwith altitude.Aerosols over the region Mount Huang are influenced by anthropogenic source of surrounding areas to a certain extent. The anion and cation of aerosolarebalanced.But thepollutant,from the Yangtze River Delta region,has no effect on the Acidity and Basicity of aerosol at Mount Huangshan.It isalso suggested that the correlation between NH4+and SO42-is0.98and these ions predominantly existed in the form of (NH4)2SO4and NH4HSO4. Backward trajectory analysis reveales that the air mass is originated from southern coastal regions, East China Sea, Yellow Sea and northern China. Due to the northern air masses through heavily polluted areas.the concentrations of water-soluble ions in these air masses are higher than other air masses.Results show that the fog/clouds at Mount Huangshan are acid,with pH vary between3.27and6.83.The mean electrical conductivity of fog/cloud samplesin2009and2011is91.8μs/cm,62.53μs/cm, respectively.The predominantly water-souble ions of fog/cloud water are SO42-,NH4+,Ca2+,NO3-,Na+,Cl-,accounting for about85%of total ionic concentrations.The proportion of other ions in fog/cloud water is less.However,similar with the aerosol,the major anion and cation of fog/cloud waterareSO42-and NH4+,which accounting for45%of total ionic concentrations. Due to the differences in contribution from Yangtze River Delta regional pollutant sources and marine sources, soluble components varied greatly in different fog/cloud events. Backward trajectory analysis reveals that fog/cloud air mass is originated from marine and surrounding area.The relationship between microphysical characteristics and aerosol is complicated in cloud events.Evolution of cloud is inhomogeneous.There are some relationship between the ionic concentration of fog/cloud and microphysical characteristics of fog/cloud.The scavenge efficiency of SO42-in PMiby cloud varies from26%to61%.The bigger is the mean diameter of cloud droplet,the higher is the value of scaveng efficiency of SO42-in PMiby cloud. |
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