Elemental composition of aerosols in Daihai, a rural area in the front boundary of the summer Asian monsoon

TSP and PM2.5 were sampled in Daihai, an Asian monsoon-sensitive region in Inner Mongolia, in summer. The aims were to evaluate the characteristics of trace elements and to investigate the influence of the summer monsoon on elemental composition there. Eighteen trace elements, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Br, Sr, Zr and Pb, were determined and their concentrations were evaluated. The TSP/PM2.5 ratio of element concentrations showed that crustal elements like K, Ca, Ti and Fe, as well as Pb, Ni and Sr were more abundant in TSP, while other elements predominated in PM2.5. Enrichment factor (EF) calculations revealed that non-crustal trace elements were more enriched in PM2.5 than in TSP. Back trajectory analysis indicated that crustal elements such as K, Ca, Ti and Fe had distinctly high concentrations associated with northerly flows, while non-crustal elements showed no clear pattern. However, non-crustal elements showed high EF values related to southeasterly flows. Principal component analysis (PCA) was also applied to the PM2.5 data to discuss the source appointment and five factors were determined.