The Major Compositions And Source Of Atmospheric Aerosol Over The Shelf Sea Of Eastern China

Shelf sea of eastern China are transition zones for large influx of mineralparticles and pollutants from Asia to the western North Pacific through atmosphericlong-range transport, so concentrations, compositions and sources of the ions arecomplicated. Atmospheric aerosol can have a significant effect on the earth’senvironment. It can influence radiation budget through their direct and indirectradiative force.In this present dissertation, the Bohai Sea (BS), the Yellow Sea (YS), and theEast China Sea (ECS) were chosen as the study areas. The marine aerosol sampleswere collected over the shelf sea of the BS and YS during spring and autumn2012and over the ECS during winter2011, summer and autumn2012, respectively. Theconcentrations, seasonal and spatial variations as well as source analysis of mainsoluble ions, trace elements, MSA and mono-carboxylic organic acids were analyzed.The main results are presented as follows:(1) Tthe mass of Total Suspended Particulates(TSP）were0.18±0.04g and0.05±0.03during spring and autumn over the BS, and the total concentration of watersoluble ions (WSI) were23.3±10.7μg·m-3and27.1±9.4μg·m-3, respectively withthe secondary ions occupied84.7%and63.7%of the total concentration. Theconcentration of every single ion followed the order of NO3-> nss-SO42-> NH4+> Cl->Na+> nss-K+> nss-Ca2+> Mg2+in spring and NO3-> nss-SO42-> NH4+> Cl-> Na+>nss-K+> nss-Ca2+> Mg2+in autumn. Concentrations of measured trace metals werehigher in autumn than in spring, and the concentrations of Al and Fe were the mostabundant with the single order of Fe> Al> Zn> Pb> V> Cu> Cd and Fe> Al> Zn> Pb>Cu> V> Cd in autumn. The level of MSA also presented the seasonal variation inaerosol samples, with the means of22.0±18.2ng·m-3, and11.4±9.6ng·m-3during spring and autumn, respectively. The concentrations of acetic and formic acids vareddifferently, and the mean concentrations were74.9±47.2ng·m-3,55.6±39.5ng·m-3，while472.5±147.3ng·m-3and264.2±131.0ng·m-3in autumn.(2) The TSP mass was0.012±0.003g, and the total concentration of water solubleions in summer over the ECS was12.3±3.1μg·m-3. The concentrations of major WSIfollowed the order of Cl-> Na+> NO3-> nss-SO42-> NH4+> Mg2+> nss-K+> nss-Ca2+in the TSP during summer over the ECS. The averaged TSP mass was0.020±0.013gand concentration of water soluble ions in the autumn cruise was21.3±8.2μg·m-3and the order of WSI during autumn over the ECS showed similar trend as the spring,indicating Cl-> Na+> nss-SO42-> NO3-> NH4+> Mg2+> nss-K+> nss-Ca2+. Thesecondary ions occupied the most part of WSI, contributing over49.2%and40.3%ofthe total WSI concentrations. The concentrations of WSI followed the order ofnss-SO42-> Cl-> NH4+> NO3-> Na+> Mg2+> nss-K+> nss-Ca2+during winter overthe ECS. The total concentrations of WSI accounted to40.9±13.2μg·m-3, and thesecondary compositions occuped67%showing a higher tendency. The concentrationsof trace metals collected over the ECS were lower than those in BS and YS. Theconcentration of trace metals in summer and autumn follows the similar order of Fe>Al> Zn> Pb> V> Cu> Cd and Fe> Al> Zn> Pb> Cu> V> Cd. There existed asignificant seasonal and difference in the concentration of Methanesulfonic acid(MSA), with mean concentrations of5.8±1.5,5.0±3.1,1.9±0.3ng·m-3duringsummer, autumn, and winter, respectively. The mean concentrations of formic andacetic acids were16.0±9.1,43.6±37.0ng·m-3in summer and66.8±56.2,50.8±45.0ng·m-3in autumn.(3) The contribution of WSI to mass concentrations of TSP samples was higher insummer than in autumn, and it was the lowest in spring. The high mass concentrationbut low mass ratio of water-soluble ions to total particles in spring could be attributedto the weak influence from dust intrusion from mainland. Overall, the correlationsbetween internal ions within each observational season showed similar patterns. Theenrichment factors of the secondary ions relative to their contents in seawater and crust were extremely high, indicating the major influence from human activity fromthe continent. K and Ca had a primary contribution of crustal materials. Characters ofaerosols indicated that Fe, Cd, Zn and Pb were enriched elements, while V was notapparently enriched. The pollution source contributions (Rp) of Cd, Zn and Pb were>97%, suggesting the overwhelming contribution by the anthropogenic emission. V hada mixed source from crustal and anthropogenic emissions.(4) Biogenic contribution was calculated based on the mass ratio of nss-SO42-/MSA.The biogenic contribution in spring cruise over the BS and YS was close with that inautumn, with values of5.5%and5.6%, respectively; while over the ECS the biogeniccontributions during summer, autumn and winter were2.2%、2.8%�'�0.8%. Highnss-SO42-and low biogenic SO42-contribution suggested that nss-SO42-fromanthropogenic emission is the dominant component of the total nss-SO42-over theShelf Sea of eastern China.