Characterization of carbonaceous aerosols during spring of 2005 in Xi'an

Concentrations of PM_2.5, PM₁₀ and organic carbon (OC), elemental carbon (EC) in atmospheric were measured in Xi'an from March to April 2005. The average concentrations of PM_2.5 in March and April were (171.5 ± 62.7) μg / m³ and (153.5 ± 54.5) μg / m³, respectively, which accounted for (51.7 ± 12.9)% during March and (53.2 ± 12.1)% during April in PM₁₀. The average OC and EC concentrations in PM_2.5 were (29.4 ± 12.5) μg / m³, (9.9 ± 4.0) μg / m³, respectively, while those in PM₁₀ were (36.9 ± 16.3) μg / m³, (13.4 ± 5.9) μg / m³, respectively. OC in PM_2.5 accounted for (77.5 ± 8.8)% of OC in PM₁₀ during spring, while PM_2.5 EC accounted for (73.0 ± 11.0)% of in PM₁₀ during spring. It demonstrated that most of OC and EC were associated with fine particles. The OC and EC in Xi'an were found to be closely correlated. The daily average OC / EC ratios constantly exceeded 2.0, which suggests that there may have secondary organic carbon in the atmospheric particles.