| Respirable particulate matter(PM10) is the primary pollutant in the atmosphere of Beijing, in which the mass fraction of organic component is about 30～50 percent,and organic acid is a most abundant species in it.Organic acids in the atmospheric particulate of the city is partly from biogenic emission,partly from anthropogenic emission,but more from oxidation of volatile orgainc compounds(VOCs) in the atmosphere.As an ultimate product of atmospheric organic component,organic acid can be eliminated from the atmosphere through dry and wet deposition, especially when recent years,the proporsion of organic acid increases in the rain,who comes a new essential factor of acid rain.Morever,atmospheric fine particle increases in hygroscopicity when it contains orgainc acid,thereby aggravate fog and haze weather.While the impact of organic acid fallen to the water to the acidity of fresh water,and to the ecosystem in the water body is unpredictable.It starts from the testing of the concentration of orgainc acid in the atmospheric particulate in this thesis,and it provides basic data and scientific train of thought to the problems above,thus promote the study of atmosperic secondary aerosol.RP1400,TE-42CTL NO-NO2-NOx analyzer and TE-49C O3 analyzer were used to monitor atmospheric particulate,NOx,and ozone respectively in Beijing and surrounding aeras before and after the Olympics,real time datas were transmitted through CDMA net.Mini-pulp and gas sampling bags made of aluminum-plastic composite film were used to collect VOCs samples on 9 am and 14 pm each day before and after the Olympics.Sampler of large flow capacity was used to collect the atmospheric particulate in Beijing during September,2006 and August,2007.Procedures of solvent extration,column seperation,derivation were carried out, followed by detection with GC/MS.The chemical compositon of organic acid in the atmospheric particulate in Beijing was analyzed.Auto-sampler of precipitation and dust and PUF passive sampler were used to collect particle dry depositon and gas dry depositon respectively in 10 sites in Beijing-Tianjin-Bohai Bay region from December,2007 to November,2008,in which the organic acid component was analyzed.The reseach objectives of this thesis are as follow:1.To have a better understanding of the variation rule of atmospheric pollutant through observation and research of the atmosphere in Beijing and surrounding aeras before and after the Olympics.To study the variation of pollutants including NOx,O3 and VOCs which are related to the secondary sources of organic acid through comparison of datas before and after the Olymoics,so as to provide scientific proofs for establishing effective measures that can prevent and control air pollution.2.To know the concentration of organic acid contained in the atmospheric particulate in Beijing,and to study the chemical composition of organic acid so as to deduce its sources.3.To know the concentration of orgainc acid in air dry deposition and the flux of organic acid particule dry deposition.And to study the regional transmission of pollutants through monitoring dry depositon in Beijing-Tianjin-Bohai Bay region.The results are as follow:1.After measures of limiting vehicles and discharge were taken,NOx,a primary pollutant in Beijing,reduced greatly,especially during the Olympic,with a decrease rate of 39%.The concentrations of VOCs druing the Olympic and the Paralympic were 33.5 and 46.8ppbv, decreased 44.3 and 22.1 percent compared with period with no limiting measures(June).O3,a secondary pollutant,was quite low during the Olympic and the Paralympic,which were 66 and 71ppb,reduced 16%and 10%compared to June when no measures were taken.Overall,those measures worked significantly to reduce pollutants in Beijing,especially when primary pollutants were reduced,secondary pollutants were also restrained.2.Total concentrations of monocarboxylic acids in PM10 varied from 61.7 to 1652.3 ng/m3, averaged 426.2 ng/m3,while in PM2.5 the concentrations ranged from 34.5 to 992.1 ng/m3, averaged 319.6 ng/m3,among which C16 and C18 were the most abundant.75%of those monocarboxylic acids distributed in the fine particle.They were apparently higher in winter and spring than in summer and autumn.Source apportionments implied that coal burning for heating was the most important anthropogenic source in winter,while automobile exhaust contributed most in other seasons.3.In the Beijing-Tianjin-Bohai Bay region,gas dry deposition of organic acid in Beijing is the highest,amounts 655.8ng/m3,while concentarions in Luancheng,Cangzhou,Yucheng, Xinglong,Baoding,Yangfang are also high,which range between 250 and 500 ng/m3, concentrations in Tanggu,Tianjin,Tangshan are relatively lower,which are below 200 ng/m3.As to particle dry deposition,Cangzhou is the most in amount,which reaches 145.7μgm-2d-1. Beijing,Xinglong,Yangfang,Yucheng,Baoding are between 70 and130μgm-2d-1.Tangshan, Tanggu and Tianjin are below 50μgm-2d-1.Congcentration of monocarboxylic acid in gas dry deposition of Beijing is higher in spring,followed by summer and winter,with autumn the love-est.Composition of monocarboxylic acid in gas dry deposition is similar to the one in the atmospheric aerosol,with C16 and C18 the most abundant.Concentration in the partile dry deposition of Beijing follows the order:summer＞spring＞winter＞autumn,C16 and C18 are also the most abundant.Organic acid both in air and particle dry deposition became significantly lower during the Olympics,which infers that when measures of limiting vehicles and discharge were taken,pollution sources of organic acids were controlled,thus decreased organic acid that were emitted to the atmosphere,so that decreases the concentration of organic acid both in the air and landed to the ground.The innovative results of the thesis are that:1.The vatiation of important pollutants including NOx,O3 and VOCs which are related to the secondary resources of organic acid after measures of limiting vehicles and discharge were taken were studied.They all decreased sharply,indicating that those measures played an important role in reducing pollutants in the atmosphere of Beijing,especially when primary pollutants were reduced,secondary pollutants were also restrained.2.Organic acid in dry deposition in the Beijing-Tianjin-Bohai Bay region were studied.It's found that composition of monocarboxylic acid in gas dry deposition is similar to the one in the atmospheric aerosol,with C16 and C18 the most abundant.Organic acid both in air and particle dry deposition became significantly lower during the Olympics,which infers that measures of limiting vehicles and discharge were effective in controlling pollution.
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