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11.
Estimation of kinetic Monod parameters for anaerobic degradation of benzene in groundwater 总被引：1，自引：0，他引：1
To date, evidence for the degradation of benzene under anaerobic conditions has been established only in few studies under
field and laboratory conditions. Recently, we demonstrated the mineralization of benzene under sulfate-reducing conditions
in a large-scale column experiment at a field site by balancing electrons (Vogt et al. in Biodegradation, 2007, in press).
Here, from a modelling approach, kinetic Monod parameters are estimated for the degradation of benzene in the columns, Monod
kinetics proved useful to simulate benzene concentrations at the column outflow. The uncertainty of the obtained parameters
is determined in a sensitivity analysis. A total mass of degraded benzene of 23 g or 80% of the total influx over a period
of three months was calculated. The estimated maximum utilization rate was calculated to be around 70 times lower than from
aerobic benzene degradation experiments. 相似文献
12.
Sébastien Lebonnois 《Planetary and Space Science》2005,53(5):486-497
Benzene has recently been observed in the atmosphere of Jupiter, Saturn and also Titan. This compound is required as a precursor for larger aromatic species (PAHs) that may be part of aerosol particles. Several photochemical models have tried to reproduce the observed quantities of benzene in the atmospheres of Jupiter (both low- and high-latitudes regions), Saturn and Titan. In this present work, we have conducted a sensitivity study of benzene and PAHs formation, using similar photochemical schemes both for Titan and Jupiter (low-latitudes conditions). Two different photochemical schemes are used, for which the modeled composition fairly agrees with observational constraints, both for Jupiter and Titan. Some disagreements are specific to each atmospheric case, which may point to needed improvements, especially in kinetic data involved in the corresponding chemical cycles. The observed benzene mole fraction in Titan's stratosphere is reproduced by the model, but in the case of Jupiter, low-latitudes benzene abundance is only 3% of the observed column density, which may indicate a possible influence of latitudinal transport, since abundance of benzene is much higher in auroral regions. Though, the photochemical scheme of C6 compounds at temperature and pressure conditions of planetary atmospheres is still very uncertain. Several variations are therefore done on key reactions in benzene production. These variations show that benzene abundance is mainly sensitive to reactions that may affect the propargyl radical. The effect of aerosol production on hydrocarbons composition is also tested, as well as possible heterogenous recombination of atomic hydrogen in the case of Titan. PAHs are a major pathway for aerosol production in both models. The mass production profiles for aerosols are discussed for both Titan and Jupiter. Total production mass fluxes are roughly three times the one expected by observational constraints in both cases. Such comparative studies are useful to bring more constraints on photochemical models. 相似文献
13.
溶解态黑碳(DBC)作为黑碳(BC)降解的中间产物,是海洋溶解有机碳碳库的重要组分,涉及全球海洋碳收支并进一步影响全球气候变化;是有色溶解有机质的重要组分,可改变水体光学环境从而对生态系统产生影响;也是一类良好的有机配体,在环境中易与金属离子形成络合物从而影响金属污染物的行为与毒性。鉴于其在气候变化、生态和环境等方面的重要影响,近年来研究者越来越关注DBC,并取得了一些基础性成果。目前,在DBC的定性认识上还存在一些模糊区域,所以DBC还没有一个明确的定义,DBC只是一个术语,特指一类由浓缩稠环母体和亲水性取代基(主要为羧基)组成的复杂有机物。在DBC的来源方面,已有证据证明BC降解能够产生DBC;但DBC很可能还存在其他来源,仍需进一步研究确认。DBC主要随水体进行迁移,并已观察到了DBC的降解现象,但目前对DBC的降解机理及速率仍不了解。在定量分析方法上,由于DBC的极性很强,且与其共存的基质相当复杂,分析DBC具有很大的挑战,其中苯多羧酸分子标志物法(BPCA)是定量分析DBC很有前景的方法之一,但目前仍存在一些难点需要解决。DBC在全球不同水体中含量变化很大,但目前的数据相当有限,不足以全面评估DBC的储量和循环周期。从DBC的定性识别、来源、迁移转化、定量分析及含量分布等方面综述DBC的研究进展,重点讨论BPCA法定量DBC的研究现状及存在问题,并展望DBC的研究方向。 相似文献
14.
Contribution of anaerobic microbial activity to natural attenuation of benzene in groundwater 总被引：7，自引：0，他引：7
S. J. Johnson K. J. Woolhouse H. Prommer D. A. Barry N. Christofi 《Engineering Geology》2003,70(3-4):343-349
Anaerobic biodegradation of hydrocarbons, using a variety of terminal electron acceptors (TEAs), is increasingly being reported both in laboratory studies and in the field. Of all the petroleum hydrocarbons, benzene is considered the most problematical due to its high toxicity and relatively high aqueous solubility. These, combined with its peculiarly stable structure, mean that it has long been considered recalcitrant in all but aerobic conditions. There is now a small, but growing, literature to suggest that this may not in fact be the case. We present an assessment of the field, encompassing reviews up to 1997 and original papers published since then. It appears that benzene is indeed degraded anaerobically, but that organisms capable of doing so are not ubiquitous. In addition, benzene degradation may be competitively inhibited by the presence of more readily degraded compounds such as toluene. Certainly, the occurrence and rate of benzene attenuation under anaerobic conditions is far more site-specific than for other benzene, toluene, ethylbenzene and xylenes (BTEX) compounds. We discuss a mathematical method for modelling redox-dependent, differential degradation rates. 相似文献
15.
根据气相色谱的原理，以常规方法为对照，在胶粘剂中苯系物检测中，采用SE—30毛细管和AC20毛细柱双柱定性，用内标法，准确测定胶粘剂苯系物，克服了单柱检测产生的误判现象。 相似文献
16.
Benzene exposure is of particular concern because recent research indicates that it can result in chronic toxicity, with an
elevated risk of carcinogenesis. Exposure to benzene from automobile exhaust can be an important occupational problem for
urban population. The present study was conducted to estimate cancer risk of population living in nine densely traffic jam
area due to contact with traffic benzene vapor during daily work. The reported lifetime unit risk factor ranges from 8.30E-8
to 1.58E-6. Of interest, this number is high and can be important public health threaten. Monitoring of environmental benzene
can help classify with high risk. Annual check up and monitoring for benzene exposure among the people living in urban area
should be set as primary prevention of benzene-related cancer for them. 相似文献
17.
《Geofísica Internacional》2014,53(2):183-198
As a result of a gasoline spill in an urban area, Electrical Resistivity Tomography (ERT), Electromagnetic Profiling (EMP) and Volatile Organic Compounds (VOC) methods were used in order to define the contamination plume and to optimize the drilling and soil sampling activities. The VOC anomalies (recent contamination) indicated that a gas station located at the study site is an active contamination source. The mature contaminated zones defined by ERT and EMP methods corresponded with low resistivity anomalies due to degradation process of the hydrocarbons contaminants. The ERT, EMP and VOC results were integrated on a map, allowing the final configuration of contamination plumes and the optimization of drilling and soil/free-product sampling. Laboratory analyses of free-product samples suggest the existence of more than one contamination event in the site, with the presence of recent and degraded-hydrocarbon contaminants classified in the gasoline range. This study shows the advantages of joint application of ERT, EMP and VOC methods in sites with active contamination source, where the existence of recent and mature contaminants in subsoil is assumed. 相似文献
18.
制备了掺杂不同含量钒和铁的FSM(Folded-sheet mesoporous materials)-16分子筛,采用X粉末衍射仪(Powder X-ray Diffractometer,XRD)、红外光谱仪(Infrared Spectrometer,IR)研究了V-FSM-16和Fe-FSM-16分子筛的结构特征和表面性质,并考查了掺杂不同量金属的FSM-16分子筛对苯氧化成苯酚催化性能的影响,探求掺杂合适金属及合适量的催化剂。实验结果表明掺杂金属钒与载体物质的量比为0.077时,催化剂的催化活性最高。 相似文献
19.
A metal plating facility in central Kentucky was required to complete a RCRA Facility Investigation to address a number of
Solid Waste Management Units at the site. Twenty monitoring wells were installed at the facility. Ground water from the wells
was sampled for total and dissolved metals, polychlorinated biphenyls, acid extractable compounds, base neutral compounds,
and volatile organic compounds. Unexpectedly, relatively large concentrations of benzene, up to 120 μg/l, were detected in
samples from some of the wells, including wells that should have been hydraulically upgradient from the facility. As a result
of the detection of benzene, the facility completed an investigation to identify the source. A nearby facility had completed
a gasoline underground storage tank (UST) closure at about the time of the installation of the 20 wells. Reportedly the UST
had small holes when removed. Three potential pathways of migration (a ditch, sanitary sewer, and a sink hole) from the nearby
facility to the metal-plating facility and residual soils with very large concentrations of benzene, toluene, ethylbenzene,
and xylenes have been identified. 相似文献