One hundred year sedimentary record of black carbon from mud area in Bohai Sea, China

在渤海泥质沉积区采集柱状沉积物样品，分析其黑碳含量和沉积通量，结合n。Pb年龄测定，探讨百年尺度黑碳沉积通量的时间序列变化对区域人类活动的响应。结果表明：（1）研究区黑碳含量和沉积通量分别为0．24--0．49mg／g平均为（0．32±0．07）mg／g和0．026～0．053mg／（cm2·a）平均为（0．040±0．008）mg／（cm2·a），黑碳含量与我国东海内陆架等海区相当，但远低于美国港湾和瑞典大陆架等污染较严重地区；（2）黑碳通量在20世纪50年代一70年代中期和90年代初一90年代末出现两个明显的峰值，分别对应于两个阶段的生物质燃烧量和煤炭、石油等化石燃料燃烧量的急剧增加；而20世纪70年代末-80年代末较低的黑碳通量以及21世纪初黑碳通量下降的趋势则分别与黄河改道事件、我国能源利用技术提高及污染控制减排措施逐步实施等有关；（3）通过比较本文结果以及国内外其它海域和湖泊的研究资料，证明黑碳沉积记录可以作为一个良好的地球化学指标，用于评估人类活动对生态环境的影响历史

The concentration and composition characteristics of soluble parent and alkylated polycyclic aromatic hydrocarbons in typical bituminous coals

Residential coal combustion (RCC) is the most important emission source of polycyclic aromatic hydrocarbons (PAHs) and black carbon (BC) in China. Their emission factors are obviously controlled by the geological maturity of coals, therefore they may be related with the concentration and composition of soluble PAHs in coals. Six types of bituminous coal differing in maturity were selected in this study to determine soluble PAHs by GC/MS after Soxhlet extraction with DCM solvent. Through analyzing 16 parent PAHs (pPAHs) and 16 alkylated PAHs (aPAHs), the paper discussed the relationship between the concentration and composition of PAHs and coal maturity. Moreover, it may be helpful to study the formation mechanism of PAHs and BC during RCC. The results show that: (1) the total PAH concentrations in the six tested coal types are within the range of 39.8~289.0 mg/kg,and the coals with a medium volatile material content on the dry and ash-free basis (V_(daf)) have higher PAHs than those V_(daf) bituminous coals with high and low volatile material contents. Various coals show a difference by seven times, which is similar to the trend of emission factors of PAHs and BC of RCC; (2) pPAHs concentrations are winthin the range of 8.3~58.4 mg/kg in the six coal types, with the highest value occurring in those coals with a V_(daf) range of 25.6%~30.5%. Their aPAHs are within the range of 31.4~236.5 mg/kg, with two peaks existing at V_(daf) values within the range of 25.6% and 35.5%, respectively; the concentrations of aPAHs are higher than those of pPAHs by four times on average. The similar ranges of PAHs concentrations in both raw coals and RCC smoke as well as higher alkylated PAHs than pPAHs, may illustrate the succession of PAHs in coal smoke from soluble compounds; (3) as for the composition, low-ringed compounds (2~3 rings) are dominated by pPAHs in coals with V_(daf) less than 25.6%, while middle-to high-ringed PAHs (4~6 rings) have dominatedly the concentrations at V_(daf) over 30%; the case is similar for aPAHs with respect to this similarity, in which 2~3-ringed compounds are the main part in bituminous coals with middle to high maturities, while 4-ringed compounds have the highest concentrations at V_(daf) of 30.5%~35.5%. This compositional trend of soluble PAHs reflects the evolution rule of geological maturity of coal chemical structure y, and it also explains, to some extent, the phenomenon of the highest emission factors of PAHs and BC for middle volatile bituminous coals during RCC