| The composition of aerosol vary widely of different regions,and cities as populated areas,health problem is very inportant that we can not ignore it.As an important part of aerosol,biological origin aerosol plays an important role in global climate change and environmental health.On the one hand,bioaerosol can affect the Earth's radiation balance directly by absorbing and scattering solar radiation,and indirectly by serving as giant cloud condensation nuclei(CCN)and ice nuclei(IN),and thereby influence cloud microphysical and climate-relevant properties.On the other hand,bioaerosol can spread human,animal,and plant disease and influence public health.With the city developing,there comes more and more haze episode,and the probability of allergy and asthma is increased.High-efficiency detected method was needed for bioaerosol.The traditional analysis methods for bioaerosol often time-consuming and can't provide specific bioaerosol concentration.In recent years,fluorescence detection technology has been developed rapidly,the emergence of on-line detection biological aerosol particle instrument,but the application in China is still small at present.Biogenic volatile organic compounds(BVOC)as a precursor of secondary organic aerosol(SOA)and accounts for the majority of global VOC emissions which emission by plants.Ocean as the important part of the earth,plays an inportant role in the climate change,and the oceanic atmosphere can also be used as background area of urban atmospheric environment,studying BVOC over the ocean can better understand of the global SOA generation.The study of stable carbon and nitrogen isotopes of ocean aerosols can help to explore the source and transport process of ocean aerosols.This study was based on two filed campaigns and the 29th and 30th China Antarctic Research Expedition,the on-line fluorescent instrument was used for domestic polluted cities at the first time,explore the marine emissions of BVOC and the distribution of stable carbon and nitrogen isotopes of ocean aerosol.The main contents and conclusions are as follows:(1)The concentrations of fluorescent bioaerosol particles in Nanjing were 1-2 orders magnitudes higher than those observed in clean areas where bioaerosols dominate the fluorescent aerosol particles.The number concentrations of bioaerosols in Nanjing and Xiamen were 0.57 cm-3(FL1),3.35 cm-3(FL2),2.09 cm-3(FL3)and 0.24 cm-3(FL1),0.78 cm-3(FL2),0.4 cm-3(FL3),respectively.The fluorescent bioaerosol in Nanjing showed clearly diurnal variation,while the diurnal variation was not obvious in Xiamen site.The concentration of fluorescent bioaerosol was decreased with size increase.The fluorescent bioaerosol particle dominated by the particle size of 1-2 mm,and all the particles with size larger than 3.8 mm were have FL2 fluorescence signal.The AF was show single peak distribution in Nanjing site(the peak value was?24),while in Xiamen site it was show bimodal(the peak values were?23 and?30).This indicates that the shape distribution of fluorescent particles in Nanjing is relatively simple.(2)The concentration of the fluorescent aerosol is influenced by the local meteorological parameters.The wind speed will increase the pollen and spore emission of the plant,resulting in the increase of the biological aerosol concentration.But when the wind speed exceeds a certain threshold,the diffusion rate of atmospheric particles will increase,resulting in the local concentration of biological aerosols decreased.Biological aerosol concentrations increase before rainfall,temperature and humidity can also affect the release of bioaerosol.(3)Nanjing results showed that the number concentrations of fluorescene aerosol particles(FAPs)were 1-2 orders of magnitudes higher than those reported in the previous studies.Especially the number fraction of FL1 showed strong correlation with MBC/PM0.8(r=0.75).The observed high values suggested that directly using the FL1,FL2,and FL3 channels to index PBAPs is not suitable for polluted areas.According to the correlation of the fraction of FAPs to total particle and MBC/PM0.8,FAPs were divided into combustion-related-type(CR type)particles and non-combustion-related-type(NCR type)particles,the ratio of CR type and NCR type particles to total particles were?11%and?5%,respectively.The concentration of NCR type particle was 0.64 cm-3,were still higher than those observed in clean background areas and previous studies in Nanjing,indicating they may also include some other fluorophores,such as dusts.(4)The concentrations of isoprene,a-pinene and b-pinene were found to be 113 pptv,28 pptv and 14 pptv,respectively,for the 29th China Antarctic Research Expedition.The concentration of isoprene was significantly higher than that of monoterpene,and the showed a good correlation.There was no significant difference in the geographical distribution of isoprene and monoterpenes in the whole cruise.Prydz Bay showed high concentrations of isoprene and monoterpenes,which had a relation with phytoplankton bloom in that area.Different phytoplankton species,wind speed and temperature can affect the concentration distribution of isoprene and monoterpene in marine atmosphere.Prydz Bay isoprene-generated SOA accounts for 0.03%of global oceanic isoprene SOA.(5)The average concentration of total carbon in aerosol total suspended particulates at the 30th China Antarctic Research Expedition was 1 ± 0.81 ?g m-3.The concentration of total carbon(TC)decreased gradually with latitude increasing(r =0.58,p<0.01).TC at low latitudes was greatly affected by terrestrial emission.29%of the samples not detected total nitrogen(TN)during the whole expedition.The average concentration of TN was 0.49 ± 0.74 ?g m-3,and the concentration of TN was much lower than that in the big cities.The concentration of TN also decreased with the increase of latitude(r = 0.37,p<0.01).The average value of stable carbon isotope?13 C was-27 ± 3.3 ‰,and ?13C had correlation with TC(r=0.34,p<0.05).The average value of stable nitrogen isotope ?15N was 0.9 ± 3.3 ‰,which was not related to TN.The distributions of ?13C and ?15N were not related to latitude.The samples in the low latitude are influenced by the two continents of the Asian continent and the Philippine Islands,and the Australian continent,carbon and nitrogen in this region may be derived from terrestrial biomass burning.Mid-latitude samples may be affected by Antarctic continental dust.The carbon and nitrogen in the high latitudes have a certain relationship with the emission of marine phytoplankton. |
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