Assessment and Implication of PAHs and Compound-Specific δ13C Compositions in a Dated Marine Sediment Core from Daya Bay, China.

PAHs in a sediment core covering ~120 years from Daya Bay in South China Sea were extracted using Soxhlet and high performance thin layer chromatography, and the compound-specific δ13C were analyzed using gas chromatography-combustion-isotopic ratio mass spectrometry. The concentrations of PAHs ranged from 99.3 to 676 ng g-1, with high molecular weight PAHs as a key component. PAHs' compound-specific δ13C ranged from -35.02‱ to -16.14‱. The patterns of 16 PAHs, molecular ratios, and compound specific δ13C compositions indicate important pyrolytic and petrogenic sources: PAHs derived predominantly from pyrogenic sources (including coal and wood incomplete combustion) before the 1960s, while after the 1960s, they derived predominantly from mixed pyrogenic and petrogenic sources (including automotive exhaust emissions, oil spills, and coal and wood incomplete combustion). Our results can provide important insights into organic pollution emissions influenced by human activities and the urbanization of Daya Bay.

Analysis of Volatile Organic Compounds by Specific Carbon Stable Isotope / 分析化学

Theδ13 C values of volatile organic compounds ( VOCs) in various emission sources and ambient air were analyzed by using thermal desorption coupled with gas chromatography and isotope ratio mass. The lowest sample concentration and peak shape quality needed for high precision and accurate analysis were investigated. Fuel evaporation ( gasoline and diesel) , vehicle exhaust, solvent evaporation, dining fumes and ambient air of different functional zones of Xiamen city were collected using Tenax TA tube, and the significant differences in δ13 C values of VOCs between these sources were observed. The δ13 C value of gasoline exhaust ( 97 # ) was heavier (-25 . 84‰) than that of dining fumes (-30 . 26‰) and theδ13 C values of fuel evaporation were heavier than that of vehicle exhaust after combustion. The average δ13 C value of atmospheric VOCs in Xiamen was at the level of -27 . 03‰ to -25 . 40‰, which was close to the δ13 C value of the evaporation and exhaust of gasoline and diesel, indicating that the VOCs in the atmosphere of Xiamen was highly influenced by transportation related sources.