Physical And Chemical Characteristics Of Atmospheric Particulate Matters In Weizhou Island,Beihai City,Guangxi Province

Atmospheric comprehensive observations were carried out in Weizhou Island,Beihai,Guangxi in order to explore the physical and chemical characteristics of atmospheric environment in the Beibu gulf,to reveal the spatial distribution of air pollutants in typical regions of Southwest China,and to explore the possible transboundary transport of pollutants.Online sampling system was used for data of fine particulate number concentration and particulate matter filter samples were also collected.Meteorological data at the meantime were obtained.Many methods,such as Ion Chromatography（IC）and Inductively Coupled Plasma Atomic Emission Spectrometry（ICP-AES）,were applied to determine water soluble ions,water soluble organic carbon,sugar,elements of PM_2.5.The key point is to analyze the characteristics of biomass combustion tracer and the potential transport paths.Statistical analysis was used to analyze the distribution characteristics of the atmospheric particulate matter and the characteristics of gaseous pollutants concentration in Weizhou Island,and the effects of meteorological factors on the concentration of particulate matter and gaseous pollutants were investigated.The air transport paths above 500 meters were explored according to the back trajectory results.Furthermore,the characteristics of atmospheric fine particulate matter concentration and gaseous pollutant concentrations under different directions in Weizhou Island were analyzed.The results showed that PM₁ mass concentration accounted for 50% of PM₁₀ total mass concentration,while PM_2.5 mass concentration accounted for 82% of PM₁₀.Particles with particle size below 1μm made up more than 90% of the total concentration of particulate matter,and the correlations between the concentration of particles and meteorological factors were weak.Cluster analysis results showed that the airflow in four directions mainly affected the atmospheric gaseous pollutants in Weizhou Island.The most frequent direction was southwest,followed by east and south direction,and northeast direction is the least.Air masses from the northeast of the mainland were severely polluted,containing relatively high SO2 and nitrogen oxides,which was mainly affected by the impact of industrial sources;air masses from the east direction were mainly polluted by O₃,the source was impacted by VOC transport from the mainland and the lack of titration effect at the same time.The concentrations of NO in air masses from the southwest were significantly higher than those in the air masses from other directions,and the air pollutants were mainly from the port and sailing vessels emissions;air mass from the south is cleaner and can dilute the atmospheric gaseous pollutants.The concentrations of water-soluble ions,water-soluble organic carbon,and carbohydrate in PM_2.5 were 16.0μg/m3 and 3.3μg/m3,respectively.The concentration of biomass combustion tracer levoglucosan is 0.3μg/m3.Levoglucosan accounted for more than 90% of the mass concentration of carbohydrate components.The concentrations of water-soluble organic carbon in PM_2.5 were higher than that those in other regions,and the biomass and fossil fuel emissions contributed greatly to the atmospheric particulate matter components in Weizhou Island.Industrial emissions from the continental coast and combustion of biomass and fossil fuels in Southeast Asia are important potential sources of atmospheric particulate matter components in the Beibu Gulf.In conclution,atmospheric fine particle number and mass concentration level is better than that of other regions of the country level background in Weizhou Island,its physical and chemical characteristics were influenced by the transport of combustion emissions from Southeast Asia and industrial emissions from the mainland.