渤海表面沉积物中石油-重金属复合污染的生物修复

对渤海中部蓬莱19-3溢油污染区域某溢油钻井平台附近海域的表层沉积物中的重金属、石油烃含量进行了分析,阐述了石油生物修复过程中沉积物中重金属浓度随着石油降解的变化规律,探讨了二者的相关性.结果表明,随着石油的降解,重金属Cr、Cu、Ni、As和Cd的浓度呈现出一种先上升后下降的趋势,并且浓度变化幅度较大.前期沉积物中重金属浓度的升高可能与石油降解有一定的相关性,后期重金属浓度降低可能是微生物、植物的作用、沉积物的再悬浮作用或重金属的纵向迁移导致的.Pb则随着修复的进行表现为浓度的持续减小,且变化幅度较平稳,这可能与活性Pb与沉水植物根系的作用以及沉积物p H和有机质含量减少有关.修复后除As(8.2%)外,沉积物中的Cr、Cu、Ni、Pb和Cd浓度的降低幅度为48.5%—69.6%,表明石油降解菌对沉积物中的重金属也有良好的修复效果.本研究将为石油污染土壤或沉积物中的重金属与石油烃复合污染的生物修复提供一定的理论基础.

渤海辽东湾海域表层沉积物有机质特征、来源及环境评价分析

为探究渤海辽东湾海域有机质的分布特征及其输入源,2014年8月于辽东湾采集了沉积物表层样品,并检测了有机质的生物地球化学指标:总有机碳(TOC)、总氮(TN)以及碳、氮同位素。结果表明:辽东湾表层沉积物样品的TOC变化范围为0.23%—1.76%,平均值为0.72%;TN的变化范围为0.02%—0.09%,平均值为0.04%。有机碳同位素值在-23.89‰—-21.82‰,平均值为-22.34‰;氮同位素的值处于5.27‰—9.68‰之间,平均值为7.43‰。粒度对碳、氮同位素值的影响不大,人为因素会对碳、氮同位素的检测结果造成影响。有机污染评价显示辽东湾的西南部及东北部海域受到一定程度的生态污染。依据经典的二元计算模式,辽东湾海源有机质贡献比例范围为51.77%—86.31%,平均值为77.66%。因此辽东湾海域的有机质输入源主要为海源有机质,陆生有机质来源主要是陆生C3植物。研究结果对于渤海陆海统筹的生态保护修复与区域污染防治提供一定的科学依据,为打响渤海攻坚战提供有力的数据参考。

Source apportionment and distribution of atmospheric mercury in urban Beijing, China

The concentration of gaseous elemental mercury (GEM) in the atmosphere of urban Beijing was meas-ured from October 2003 to September 2004 to investigate the origins and spatial-temporal variations of atmospheric Hg. The mean value of Hg concentration is 17.1 ng·m-3 (n=653). The atmospheric Hg data showed spatial-temporal variations throughout the duration of our observation. The maximum GEM concentration (53.7 ng·m-3) was observed at Gucheng in the western area of urban Beijing. The GEM concentrations increased from the north to the south of the studied area, and were higher in winter than in summer. The highest and lowest monthly averages of GEM concentrations were measured to be 23.3 and 4.1 ng·m-3 in January and July, respectively. In addition, GEM concentrations are higher in the daytime than at night in Autumn and from 14 March to 15 April, but daily GEM variation showed an inverse pattern from 22 April to 22 May. In winter, two peak values of GEM concentrations occurred at 13:30 and 21:30. Daily variation of GEM concentrations in summer was the lowest in the four seasons. Mercury from coal combustion was estimated to be the main source of anthropogenic emissions in Beijing from October 2003 to September 2004. Additionally, Hg emission from natural gas burning was estimated to be another dominant source of atmospheric Hg in Beijing.

Source diagnostic and weathering indicators of oil spills utilizing bicyclic sesquiterpanes

Bicyclic Sesquiterpanes （BSs） are ubiquitous components of crude oils and ancient sediments. BSs in crude oils and diesel oil were identified and characterized, the effects of moderate weathering on BS distributions were discussed, and a methodology using diagnostic indices of BSs was developed for oil correlation and dif- ferentiation. The results showed that crude oils and oil products had different abundances and distributions of BSs and, consequently, resulted in different diagnostic ratios. The selected diagnostic ratio indices of BSs, such as BS4/BS5 （ratio of 4,4,8,9,9-pentamethyl-decahydronaphthalene to 8/3 （H）-drimane）, BS6/BS5 （ratio of 4,4,9,9,10-pentamethyl-decahydronaphthalene to 8/3 （H）-drimane）, BS8/BS9 （ratio of the second peak to the third peak of C16 sequiterpane）, and BS8/BSIO （ratio of C16 sequiterpane to 8fl （H）-homodrimane）, still maintained better stabilities （%RSD 〈 5%） after weathering for 30 d. The longer weathering process （150 d） had some effect on such ratios （5% 〈 %RSD 〈 10%）. The facts of the uniqueness, abundance in petroleum, and chemical stability of BSs enable them to be suitable as an effective diagnostic means for identifying spilled oil with moderate weathering, particularly for lighter refined product samples that are difficult to identify by current techniques.

Evaluation of diagnostic ratios of medium and serious weathered oils from five different oil sources

Laboratory experiments were conducted to simulate oil weathering process, a medium to long term weathering process for 210-d, using samples collected from five different oil resources. Based on relative deviation and repeatability limit analysis about indexes of these samples, the results show there had been significant changes in diagnostic ratios among the initial and weathered samples of different oils during this process. Changes of selected n-alkane diagnostic ratios of all oil samples displayed more obviously than diagnostic ratios of terpanes,steranes and PAHs in this process. Almost all selected diagnostic ratios of terpanes, steranes and PAHs can be efficiently used in tracking sources of hydrocarbon pollution, differentiating from the n-alkane diagnostic ratios.In these efficient diagnostic ratios, only four ratios maintained good stability in the weathering processes and are more suitable because their relative deviation（RSD） are lower than 5%.

Thermal simulation of the formation and evolution of coalbed gas

Thermal simulation experiment of gas generation from the peat and the coals were performed using the high temperature and pressure apparatus, at temperature ranging from 336.8-600℃, a pressure of 50MPa and two heating rates of 20℃/h and 2℃/h, and the evolution and formation of coalbed gas components were studied. Results show that for the coals, the gaseous products are mainly composed of hydrocarbon gases. However, for the peat the content of hydrocarbon gases in gaseous products is lower than that of non-hydrocarbon components. In the generated hydrocarbon gases methane is predominant and heavy hydrocarbon gases (C2-5) are present in small amount. Meanwhile, carbon dioxide (CO2) predominates the generated non-hydrocarbon gases, and hydrogen (H2) and sul-furated hydrogen (H2S) are existent in trace amount. It is also observed that temperature is the main factor controlling the evolution of coalbed gas generation. With increasing vitrinite reflectance, methane rapidly increases, CO2 sightly increases, and C2-5 hydrocarbons first increase and then decrease. The peat and Shanxi formation coal have a higher generative potential of coalbed gases than coals and Taiyuan formation coal, respectively, reflecting the effect of the property of organic matter on the characteristics of coalbed gas component generation. In this study, it is found that low heating rate is favorable for the generation of methane, H2 and CO2, and the decomposition of C2-5 hydrocarbons. This shows that heating time plays an important controlling role in the generation and evolution of coalbed gases. The results obtained from the simulation experiment in the study of coalbed gases in natural system are also discussed.

Study on kinetics of hydrocarbon generation from coals in the Qinshui Basin

A new method for the quantitative assessment of hydrocarbon generation potential from coals by means of the chemical reaction kinetics has been developed gradually over the recent years. In this paper, the kinetic parameters of hydrocarbon gas generation are determined by high tem-perature and pressure, and closed- system thermal simula-tion for Late Paleozoic coals in the Qinshui Basin and the kinetic characteristics and the histories of hydrocarbon gas generation were studied using the parameters obtained. Re-sults show that during the longer period from the Triassic (T) to the Middle Jurassic (J2), the coal-derived methane yield increased more slowly under lower palaeogeotemperature in the Qinshui Basin; however, the shorter period from Late Jurassic to Early Cretaceous, the coal-derived methane yield increased more rapidly under higher palaeogeotemperature. The correlation between the thermal simulation and the fac-tual data shows that C1/ (C1+C2―4) coefficients computed by the histories of methane and C2―C4 hydrocarbon generation can provide evidence for the identification of the genesis of coal bed gas in the different areas of the Qinshui Basin. The kinetic simulating experiment of hydrocarbon generation for the peat considered as the original matter of coal formation was performed for the first time and the simulated results were compared with the characteristics of hydrocarbon gen-eration from coals undergoing various palaeogeotemperature in the Qinshui Basin. The result indicates that the peat has a higher potential of hydrocarbon generation than that of coals. Therefore, the hydrocarbon generation results obtained from kinetic simulation for coal with higher maturation rank could not stand for their original hydrocarbon generation potential and thus would lead to an underestimation for coal-bed gas resource. The generative amount of coal-derived gas in the Qinshui Basin was predicted using kinetic simula-tion results for the peat and their maximum was estimated. The calculation shows that the generative amount of coal-derived gas from Taiyuan Formation and Shanxi For-mation coal-beds in the Qinshui Basin is the highest in Yangcheng area, higher in Qinyuan area and the lowest in Huoshan area. Therefore, the conditions of coal-bed gas gen-eration are the best in Yangcheng area, the second in Qinyuan area and not very good in Huoshan area.

Experimental study to confirm the existence of hydrocarbon under high pressure and temperature of deep lithosphere

Pyrolysis of lignite was conducted at high temperatures from 400 to 700℃ and high pres- sures of 1 and 3 GPa in a closed system in order to investigate pressure and temperature effects on or- ganic matter maturation. The data indicated that the total yield of liquid hydrocarbons decreased with increasing pressure and the maximum of production was obtained at a higher temperature. The alkanes show more mature characteristics with increasing temperature at a given pressure, conversely, high pressure significantly hinders the thermal evolution of geological organic matter. The experimental results also demonstrated that the relative abundance of high molecular weight hydrocarbons may exist under the conditions of the lower lithosphere, which not only breaks through the traditional concept that alkanes mainly present at stage of “oil window”, but also en- hances the possibility to find the oil in the high tem- perature and pressure areas.