Physicochemical Property And Health Risk Assessment Of Surface Particulate Matter On Different Landcover In China

The underlying surface is the boundary of the movement of the lower atmosphere,which affects the energy budget and material exchange process at the land-air interface of the earth system.As one of the main sources of atmospheric aerosols,surface particulate matter on solid underlying surface can affect biogeochemical cycles,environmental conditions and human health.In this study,surface particulate matter samples were collected in 16 areas including Beijing,Lanzhou,Gansu and Zhangjiajie,Hunan for three years.The differences of grain size distribution,oxide and heavy metal contents in road sediments,farmland soils and desert sediments were revealed.Based on the results of sample collection and literature data,a dataset of soil heavy metals in China was reconstructed to reveal the distribution characteristics and regional differences of soil heavy metals in China.The effects of soil heavy metals and atmospheric particulate matter on ecological environment and human health were further evaluated.The main contents and conclusions of this paper are as follows:（1）Particle size characteristics of surface particulate matterIn the study area,the median particle size of the surface particles ranged from21.1μm to 272.7μm,and the difference of particle size of the same underlying surface was 2 to 3 times.Grain size is influenced by human activities,season and geographical location.The curve of road sediment in Lanzhou shows a bimodal distribution,the main peak value is 44.7～50.2μm,and the content of particles less than 100μm accounts for 64.65%.The peak value in Beijing is 317.0～355.7μm,and the content of particles less than 100μm accounts for 30.22%.The main peak of the Taklimakan Desert is 100.2～112.5μm,and the peak of the Tengger Desert is251.8～282.5μm.（2）Composition and source of surface particulate matterSiO₂ is the main component of surface particulate matter,in which the content of SiO₂,Al₂O₃ and Ca O accounts for 62.2%～88.2%.The Ca O and Na₂O contents in the southern road sediments studied were more than 10 times different from the background values.Under the influence of traffic activities,the contents of Zn and Pb in the road sediments of Beijing,Lanzhou,Gansu and Zibo,Shandong were more than 3 times of the background values.The contents of Mn and Ni have little difference with the soil background value,and they mainly come from natural sources.（3）Content and distribution of heavy metals in soil of ChinaThe average content of heavy metals in soil in China are Zn（103.47 mg/kg）>Cr（69.54 mg/kg）>Pb（38.30 mg/kg）>Cu（32.72 mg/kg）>Ni（31.34 mg/kg）>As（11.83 mg/kg）>Cd（0.39 mg/kg）>Hg（0.13 mg/kg）.Soil heavy metal content distribution is affected by human activities and natural background,and heavy metal content in the south is higher than that in the north.The contents of Zn,Cu and Pb in29,28 and 27 provinces were more than the soil background value,while the contents of Cr and Ni were more affected by the soil background.（4）Health risk assessment of heavy metals in soil and atmospheric particulatesThe potential ecological risk of heavy metals in soil of southern China is obviously higher than that of northern China.Guangxi,Yunnan and Guangdong provinces belong to the strong risk level,and their comprehensive potential ecological risk index is 459.20,426.85 and 401.87,respectively.In China,90.3%and 83.9%of provinces are polluted by Cd and Hg,respectively.The total non-carcinogenic risk（HI）of heavy metals were all less than 1,and the carcinogenic risk Cr(1.50×10^-7)>Ni(1.35×10^-9)>Cd(1.26×10^-10),lower than the threshold range.In addition,when the PM_2.5 concentration rises by 100μg/m³,the incidence of scarlet fever and measles in eastern China will increase by 10.79% and 6.69%,respectively.