Abundance and 14C-based source assessment of carbonaceous materials in PM2.5 aerosols in Guangzhou, South China

Özet

In this study, the carbonaceous aerosols were separated into organic carbon (OC), water soluble OC (WSOC),water soluble humic-like substances (HULIS), water soluble non-HULIS, water insoluble OC (WINSOC), and sootcarbon (SC). Then the abundance and14C content of carbon fractions were determined to assess the contributionof contemporary versus fossil sources. The results showed that the OC fraction is the major carbon fraction, theOC sub-fractions such as WSOC, HULIS, non-HULIS, and WINSOC accounted for 39.5%–66.7%, 24.8%–43.2%,11.9%–23.5%, and 31.3%–55.2% of total carbon (TC), respectively. The14C data show that the contribution ofcontemporary carbon (fc) to TC is 38.3%–63.5%, all carbon fractions were mixtures of carbon derived fromcontemporary and fossil sources. Thefcvalues of OC (38.8%–63.9%) more than that (25.7%–46.6%) of SC in thesame sample, indicated OC generally contained more contemporary carbon than SC. The WSOC and HULIS hadrelatively higherfclevels than the corresponding WINSOC and thefcvalues of WINSOC all less than 45%,indicated that the insoluble organic fractions in PM2.5samples were dominated by fossil fuel related sources.These results suggested that the contemporary and fossil contributions for different carbon fractions are dif-ferent. In addition, the seasonal and spatial variations of contemporary and fossil contributions to carbonfractions indicated that the PM2.5samples collected during summer at background site (Maofengshan, MFS) andwinter at urban site (Wushan, WS) have relative high contribution from contemporary sources, suggested thedifferences of primary and secondary sources at the two sites.