| Polycyclic aromatic hydrocarbons (PAHs) in rain, cloud/fog water and particles (PM2.5) samples collected at Mount Taishan were determined to evaluate their concentrations and variations. Individual precipitation events were sampled for 2 years from Sept.2005 to Aug.2007; PM2.5 and cloud/fog water samples were collected at Mount Taishan in an autumn-winter period (Oct.18-Nov.27) of 2008. In precipitation samples, the mean concentration of PAHs in the samples ranged from 1.76 (BaA) to 33.31 (PhA) ng/l, and the volume-weighted mean concentration of total PAHs was 81.16 ng/l. PhA was the most abundant compound with a volume-weighted mean concentration of 33.31 ng/L. The next most abundant compound was Flu, with a concentration of 16.61 ng/L. Other PAHs compounds occurred at concentrations lower than 10 ng/L. Six potential carcinogenic PAHs (BaA, BbF, BkF, BaP, Ind, DbA), as proposed by the International Agency for Research on Cancer (IARC) (1984), were not present at high concentrations, accounting for only 13.1% of the total PAHs. For PM2.5 samples, the total PAHs concentration in PM2.5 was 6.88 ng/m3. BbF was the predominant compound, with a mean concentration of 1.62 ng/m3, with a burden of over 23% of the total PAHs concentration; FluA and Pyr were the next most abundant compounds, contributing 14.21% and 10.39% of the total, respectively; the contribution of other compounds was lower than 10% of the total. Lower molecular weight (LMW) PAHs had much lower concentrations than higher molecular weight (HMW) PAHs; especially the potentially carcinogenic PAHs (BaA, BbF, BkF, BaP, InP, DbA), which were present at high concentrations, accounting for over 51.30% of the total concentration. The mean concentration of PAHs in the cloud/fog water samples ranged from 5.93 (BkF) to 79.81 (PhA) ng/l, and the volume-weighted mean concentration of total PAHs was 302.64 ng/l. PhA was the most abundant compound, with a mean concentration of 79.81 ng/L. Flu and Ane were the next most abundant compounds, with mean concentrations of 41.64 ng/L and 27.83 ng/L, respectively. The LWM PAHs (2-3 rings) were predominant in the cloud/fog water, contributing 61.71% of the total PAHs concentration. BbF had the highest concentration (23.30 ng/L) in the six potentially carcinogenic PAHs compounds. Contrast with other research, low concentrations of PAHs were found in the Mount Taishan site. Typical seasonal trend was found in PAHs study of precipitation phase. Mean concentrations of total PAHs varied from 58.36 ng/L to 92.29 ng/L in summer and winter, respectively. Most of the individual PAHs compounds have significant negative correlations with rainfall amount. Pyrene, Benzo[a]anthracene, Benzo(b)fluoranthene, Benzo(k)fluoranthene and Benzo(a)pyrene have significant positive correlations with Na+ and Cl" in rain water. Good positive correlations also were found between pH of precipitation and PAHs including BaA, BbF, BaP. In particle research, positive relationships were found between total PAHs fluxes and SO2 (r=0.670) and CO (r= 0.504), suggesting that PAHs, SO2, and CO may originate from the same sources, such as combustion activities. Both the diagnostic ratio and factor analysis indicated that PAHs in atmosphere depositon (including precipitation, particle and cloud/fog water) mainly originated from coal combustion in Mount Taishan region.In this research, PAHs in rain, cloud/fog water and particles (PM2.5) samples collected at Mount Taishan were determined to evaluate their concentrations, variations and corrolations with other factors including meteorological parameters and air pollutants. It is importanct to analy the sources and the transfer of PAHs in the atmosphere. The research refects the PAHs sources, polltants levels and varations more effectively because of the character of sampling site-Mount Taishan, which is far away from ground level pollution sources and accordingly influence of local sources is limited. And it is necessary to do this research in order to reflect the transportation of PAHs and control the PAHs pollution. |
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