Observation Study Of Aerosol Activation Characters In Linan And Analysis Of PM₁₀ And Its Chemical Compositions At Mountain Tai

Cloud condensation nuclei (CCN) is of vital importance in aerosol-cloud interactions, forit can quantitatively relate aerosols to cloud. Aerosol size and chemical compositions canimpact aerosols‘ability of being CCN, thus observation studies of aerosol activationcharacteristics and chemical composition are required. The chariteristics of PM10and itschemical compositions were investigated at Moutain Tai, a high altitude station in NorthChina Plain, from Dec2010to Jul2011; moreover, the aerosol activation characteristics werestudied at LinAn station, a regional background station of Yangtze delta regional, from Jan toOct2013.The measured average aerosol activation ratio at LinAn varied with supersaturation, andthe maximum activation ratio decreased with the decrease of supersaturation. Larger aerosols(~300nm) were found to be more hygroscopic and more homogeneous, while smallerparticles (40~70nm) were more heterogeneous and less hygroscopic. The CCN activation ratioin Jan was much higher than the campaign average, and the maximun activation ratio undersmall supersaturation was also much higher than the campaign average, this may resulted bythe influence of haze-fog weather to aerosol diameters and chemical compositions. The CNnumber size distribution have two peaks and significantly increaseed at Aitken size rangeduring the biomass burning period; meanwhile, and the CCN number size distribution movedtowards to lager diameters, indicating the influence of insoluable chemical compositions ofsmall particles on CCN activation.The annual average mass concentration of PM10was68.4μg/m3, and inorganics saltcounted for64.7%in PM10, while carbon aerosol counted for17.4%. The mass concentrationof inorganics increased gradually from the Spring Festival, reached its peak in summer, thendecreased in autumn and became lowest in winter. The mass concentration of OC increasedfrom the Spring Festival to autumn and reached the minimum level in winter. Similar patternhad been found in the mass concentration of EC; however, the concentrations of EC betweensummer and autumn was much smaller. The ratio of secondary organic carbon (SOC) to OCwas above50%for all four seasons with an annual average of58.5%. Back trajectory analysis showed that when Mount Tai was mainly influenced by air masses from the southernarea and megacities, mass concentrations of PM10and its components were high; while whenit was mainly influenced by air masses from the Northwest China through long distancetransportation, the mass concentrations of PM10and its components were much lower.