| Carbonaceous aerosols have significant impact on climate change and human health,and have a greater impact on urban areas,but rural and background areas are also affected to a certain extent.In this study,samples of fine particulate matter(PM2.5,particle size≤2.5μm)were collected from a village in Yudu Rural,Ganzhou City,Jiangxi Province from September 2017 to August 2018.Concentration levels of carbonaceous components（TC,OC,and EC）and double-carbon stable isotopic compositions(δ13CTC andδ13CEC),combined with Bayesian stable isotope mixture models,quantify the contribution of each potential pollution source to total carbon and elemental carbon,and explore carbonaceous the seasonal variation characteristics of aerosol pollution levels and pollution sources,and the long-distance transport contribution of carbonaceous aerosols during the sampling period is discussed using analytical methods such as backward trajectory models.Based on findings of this study the following conclusions have been drawn:（1）The concentration of total water-soluble ions in PM2.5 is higher in autumn and winter than in spring and summer.The four main water-soluble ions are SO42-,NO3-,NH4+and K+.The first three ions account for 93.00%of the total ions,and K+concentration is particularly prominent in winter.Combined with the results of ion correlation and principal component analysis,the sources of Yudu rural are similar all year round,mainly including soil source,biomass combustion source,fossil fuel source and secondary source,indicating that the sampling point PM2.5 there is the influence of man-made pollution sources.Combined with the ion correlation and principal component analysis results,the sources of the four seasons in Yudu rural were similar,mainly including soil sources,biomass burning sources,fossil fuel sources and secondary sources,indicating that there was a contribution of human pollution for PM2.5 in the study area.（2）The annual average concentrations of carbonaceous components TC,OC and EC in PM2.5 were 8.79±4.62μg/m3,8.48±5.12μg/m3and 0.49±0.34μg/m3,respectively.The concentrations all showed the highest in winter and the lowest in summer,which is close to the background area and far lower than the concentration level of cities in the north and south.The OC/EC ratio and correlation analysis showed that most of the OC/EC ratios were between 10 and 30,and the carbon component had a good correlation with nss-K+,indicating that biomass combustion emissions were the main source of carbon components.During the sampling period,the SOC content accounted for 61.5%of the OC,indicating that there was SOC pollution in Yudu rural.（2）The annual average values of stable isotopes of total carbon and elemental carbon in PM2.5 were-27.14±1.71‰and-26.24±1.37‰,which showed seasonal variation characteristics of positive in autumn and winter and negative in spring and summer.The analysis results of the Bayesian model and the backward trajectory model show that the combustion of biomass burning,vehicle exhaust and coal combustion are the main sources of total carbon and elemental carbon in Yudu villages.The sources are C3 plant combustion and vehicle exhaust,with an average annual contribution of 47.1%and 35.7%,followed by coal combustion and C4 plant combustion,accounting for 15.8%and 1.4%,respectively;the main sources of elemental carbon are vehicle exhaust and C3 plants.Combustion contribution,45.3%and 38.0%,respectively,followed by coal combustion and C4 plant combustion,14.6%and 2.2%,respectively.The source analysis of total carbon and elemental carbon shows that biomass burning contributes to the rural area of Yudu.Yudu rural area is mainly affected by regional pollution,with seasonal changes.The rural area of Yudu is mainly affected by local regional pollution,The local air mass transport is dominant in autumn and winter,and there is marine air mass in spring and summer.To sum up,Carbonaceous aerosols in PM2.5 in Yudu Village mainly come from biomass combustion,vehicle exhaust and coal combustion.The source analysis of total carbon and elemental carbon showed that bio-combustion made a prominent contribution to the rural areas,and the proportion of SOC showed that the contribution of secondary organic aerosols was not small.The backward trajectory of the air mass shows that Yudu Village is mainly affected by local regional pollution. |
