A 200-Year Record of Polycyclic Aromatic Hydrocarbons Contamination in an Ombrotrophic Peatland in Great Hinggan Mountain, Northeast China

Peat bogs are regarded as one of the faithful archives of atmospheric polycyclic aromatic hydrocarbons(PAHs) deposition, and a large number of studies on PAHs accumulation in peatlands have been reported in Europe and North America. Comparatively little information is available on peat chronological records of atmospheric PAHs flux in China. We investigated the concentrations and historical accumulation rates of PAHs(AR PAHs) through geochemical analysis of three 210Pb-dated ombrotrophic peat cores from Great Hinggan Mountain, northeast China. Eight USEPA priority PAHs were detected and they are naphthalene(Nap), acenaphthylene(Acl), acenaphthene(Ace), fluorence(Flu), phenanthrene(Phe), anthracene(Ant), fluoranthene(Fla) and pyrene(Pyr), respectively. The average total eight PAHs(tPAHs) concentrations are 135.98- 262.43 μg kg-1 and the average AR tPAHs over the last two centuries are 96.45- 135.98 μg m-2 yr-1. The Ace, Acl and Phe account for 30.93- 54.04%, 25.29- 35.81%, and 9.14- 19.84% of the tPAHs, respectively, and have significant positive correlations with the tPAH. As a result, they are regarded as the iconic compounds of PAHs pollution in this area. A ca.200-yr atmospheric PAHs contamination history was reconstructed from the temporal sequences of bothconcentration and AR tPAHs, suggesting the variation of local environmental pollution. The main sources of the PAHs are identified by two isomer ratios as petrogenic origin including oil extraction and refining process as well as their combustions for industrial development. In addition, the contribution of coal combustion for industrial activities and resident heating could not be ignored. But prior to 1860, the undeveloped industry and most of agricultural activities might mainly account for the low level of PAHs, although it could infer a long-range input of atmospheric PAHs from other industrial areas. Therefore, there is a global implication to study longterm PAHs pollution records and all the results will provide practical significance in formulating policies to achieve sustainable and healthy development.

Molecular distribution and seasonal variation of hydrocarbons in PM_(2.5) from Beijing during 2006

Normal （n）-alkanes and polycyclic aromatic hydrocarbons （PAHs） in PM2.5 were collected from Beijing in 2006 and analyzed using a thermal desorption-GC/MS technique. Annual average concentrations of n-alkanes and PAHs were 282 ±96 and 125 ± 150ng/m^3, respectively： both were highest in winter and lowest in summer. C19-C25 compounds dominated the n-alkanes while benzo[b]fluoranthene, benzo[e]pyrene, and phenanthrene were the most abundant PAHs. The n-alkanes exhibited moderate correlations with organic carbon （OC） and elemental carbon （EC） throughout the year, but the relation- ships between the PAHs, OC and EC differed between the heating and non-heating seasons. The health risks associated with PAHs in winter were more than 40 times those in spring and summer even though the PM2.5 loadings were comparable. Carbon preference index values （〈1.5） indicated that the n-alkanes were mostly from fossil fuel combustion. The ratios of indeno[123-cd]pyrene to benzo[ghi]pyrelene in summer and spring were 0.58 ± 0.12 and 0.63 ± 0.09, respectively, suggesting that the PAHs mainly originated from motor vehicles, but higher ratios in winter reflected an increased infuence from coal, which is extensively burned for domestic heating. A comprehensive comparison showed that PAH pollution in Beijing has decreased in the past 10 years.