Carbonaceous species in PM2.5 in the coastal urban agglomeration in the Western Taiwan Strait Region, China

Abstract

The carbonaceous species and potassium in PM2.5 were measured in the coastal urban agglomeration in the Western Taiwan Strait Region (WTSR), China in November 2010, January, April and August 2011, with the objectives to understand the spatiotemporal distribution of carbonaceous aerosols and to estimate the contribution from biomass burning and non-biomass burning to carbonaceous aerosols in this region. The average concentrations of organic carbon (OC) and elemental carbon (EC) in PM2.5 at the urban sites in the WTSR were 12.7±4.3μgm−3 and 2.3±0.9μgm−3, respectively, with the maxima in January/April and minima in August for most sites. It was found that the OC concentrations on no-rain days were higher than those on rainy days due to precipitation scavenging. Total carbonaceous aerosol (OC×1.6+EC) made up 32.1±15.6% of PM2.5. High OC/EC ratios (average 5.8) indicated the formation of secondary organic carbon (SOC), which contributed higher to the OC in January than that in August. Strong correlations were observed between biomass-burning potassium (K+bb) and OC (R2=0.56, p<0.01) and EC (R2=0.54, p<0.01) in November. It was roughly estimated that 42.1±15.1% of total carbon (TC) in November were attributed to biomass burning, which suggested that non-biomass burning was the main source of carbonaceous materials in aerosols in the coastal urban agglomeration in the WTSR.