苯高效降解菌群富集及其降解机理研究

微生物绿色、低耗、原位修复去除污染土壤与地下水中可降解污染物日益受到关注.本研究从江苏某农药厂苯系物污染土壤中以苯为唯一碳源富集获得苯降解菌群.在28℃、pH=8.0、添加100 mg·L^-1酵母粉条件下,该菌群在6 h内完全降解100 mg·L^-1的苯,利用Q-TOF解析出苯酚和邻苯二酚等主要代谢产物,并通过PCR扩增出苯酚单加氧酶基因（GenBank登录号：MW388722）.该菌群30 h内可完全降解30 mg·L^-1的苯、甲苯和乙苯混合物,高通量测序结果显示该菌群主要含有Cupriavidus、Arthrobacter、Dyella、Corynebacterium、Microbacterium等菌属,其中Cupriavidus为优势菌,菌群群落结构稳定且可高效降解苯,具有潜在的应用前景.     

Characterization of volatile organic compounds in the urban area of Beijing from 2000 to 2007

Beijing is one of the most polluted cities in the world. In this study, the long-term and continuous measurements of volatile organic compounds (VOCs) in the urban area of Beijing, specifically at Beijing 325 m Meteorological Tower, were conducted from 2000 to 2007. The annual record of VOC trends exhibited in two different phases was separated in 2003. Records show that VOC concentrations increased from 2000 to 2003 due to the abrupt increase in vehicle number. Contrarily, since 2003, there had been a decrease in VOCs concentrations as the policy on gasoline and air pollution was implemented. Toluene, benzene, and i-pentane are the chemicals that abound in and are directly related to vehicle activity, such as in vehicle exhaust and gasoline evaporation. Furthermore, records indicate that there had been seasonal variation in VOCs levels in that VOCs level in summer is higher than that in winter. As such, temperature is considered to significantly contribute to VOCs in Beijing. Records also show that VOCs level was high in the morning and during rush hours in the evening. In contrast, VOCs level was low during midday due to photochemical destruction with OH radical and dilution effect. In this study, a particular benzene to toluene ratio range (0.4-1.0) was used as the indicator of air propelled by vehicular exhaust. We also applied the correlation coefficients between BTEX and i-pentane to evaluate evaporation influence to ambient BTEX in the Beijing urban area.     

2009年北京市苯系物污染水平和变化特征

采用Tenax-TA/吸附热解吸、光离子化气相色谱法(GC-PID)对北京市大气中苯系物(BTEX)的小时平均浓度进行了为期1年的观测.结果表明,苯、甲苯、乙苯、间/对-二甲苯和邻二甲苯的年平均浓度分别为:4.43、7.03、2.27、4.18和2.06μg.m-3.苯系物之间具有很好的同源性,其浓度存在明显的日变化和季节变化,这些变化特征与交通尾气排放、采暖期化石燃料燃烧、光化学反应活性等密切相关.苯与甲苯特征比值(B/T)的分析表明,交通尾气排放是北京市大气中苯系物的主要来源,冬季和早春采暖期化石燃料燃烧也是北京市大气中BTEX的重要来源之一.乙苯与二甲苯比值(E/X)的季节变化为:夏季>春季>秋季>冬季,与北京市大气光化学反应活性季节变化趋势相似.2009年北京夏季总苯系物的平均浓度比2004年夏季减少了2/3,表明北京市政府为改善空气质量所采取的一系列控制措施十分有效.     

Levels, sources and health risks of carbonyls and BTEX in the ambient air of Beijing, China

The atmospheric concentrations of carbonyls and BTEX (benzene, toluene, ethylbenzene, m,p-xylene and o-xylene) were measured simultaneously at a same sampling site in Beijing from September 2008 to August 2010. The average concentrations of the total measured carbonyls during autumn, winter, spring, and summer were 37.7, 31.3, 39.7, 50.5 μg/m³, respectively, and maximal values for their diurnal variations usually happened at noontime. In contrast to carbonyls, the average concentrations of the total measured BTEX during the four seasons were 27.2, 31.9, 23.2, 19.1 μg/m³, respectively, and minimal values for their diurnal variations always occurred in the early afternoon. The average concentration for carbonyls increased about 24% from September 2008-August 2009 to September 2009-August 2010, for BTEX, increased about 15%. Integrated life time cancer risks for three carcinogens (benzene, formaldehyde and acetaldehyde) in Beijing exceeded the value of 1E-06, and the hazard quotient (HQ) of non-cancer risk of exposure to formaldehyde exceeded unity.     

气相色谱法同时测定苯系物和汽油化合物

气相色谱法具有较高的灵敏度和良好的线性关系。按照EPA QA／QC的要求,将该方法运用于实际样品分析。结果表明。水中汽油检出限为0．04mg／L。水中苯系物检出限为0．003-0．005mg／L,土壤中汽油检出限为0．5mg／kg,土壤中苯系物检出限为0.005-0．008mg／kg。样品加标回收率为97．1％～106．8％。变异系数为2．1％～4．6％,结果令人满意。     

便携式顶空/气相色谱/质谱联用法快速测定水中苯系物

建立了以便携式顶空/气相色谱/质谱联用技术快速测定水中苯系物的方法,该方法适用于水中苯系物的应急监测。     

Anaerobic BTEX degradation in soil bioaugmented with mixed consortia under nitrate reducing conditions

Different concentrations of BTEX, including benzene, toluene, ethylbenzene, and three xylene isomers, were added into soil samples to investigate the anaerobic degradation potential by the augmented BTEX-adapted consortia under niwate reducing conditiom. All the BTEX substrates could be anaerobically biodegraded to non-detectable levels within 70 d when the initial concentrations were below 100 mg/kg in soil. Toluene was degraded faster than any other BTEX compounds, and the high-to-low order ofdegradation rates were toluene>ethylbenzene>m. xylene>o-xylene>benzene>P. xylene. Nitrite was accumulated with nitrate reduction. but the accumulation of nitrite had no inhibitory effect on the degradation of BTEX throughout the whole incubation. Indigenous bacteria in tIle soil could enhance the BTEX biodegradation ability of the enriched mixed bacteria. When the six BTEX compounds were simultaneously present in soil, there was no apparent inhibitory effect on their degradation with lower initial concentrations. Alternatively, benzene, o-xylene, and P-xylene degradation were inhibited with higher initial concentrations of 300 mg/kg. Higher BTEX biodegradation rates were observed in soil samples with the addition of sodium acetate compared to the presence of a single BTEX substrate. and the hypothesis of primary-substrate stimulation or cometabolic enhancement of BTEX biodegradation seems likely.     

Occurrence and attenuation of specific organic compounds in the groundwater plume at a former gasworks site

The changing contaminant pattern with travelled distance was investigated in the anaerobic groundwater plume downstream from an extended zone containing residual NAPL at a former gas manufacturing plant. With increasing distance, O- and N-heterocyclic aromatic compounds are enriched in the plume relative to the usually assessed coal tar constituents (poly- and monocyclic aromatic compounds). In a first approximation, the overall concentration decrease of the investigated compounds follows a first order overall decay. The half life distance in the plume downgradient from the source varied between 20 m for benzene and up to 167-303 m for alkyl-naphthalenes. Acenaphthene is degraded only within about 50 m downstream from the source area, then its concentration remains constant (ca. 180 microg/l) and far above the legal limit. Dimethyl-benzofurans were the most recalcitrant among all compounds which could be quantified with the analytical method available. The overall groundwater contamination in the plume is seriously underestimated if only BTEX and 16-EPA-PAHs are monitored.     

粘土改性条件的研究Ⅰ.膨润土的改性

考察了改性膨润土的致孔剂加入量、溴化十六烷基三甲胺 (CTMAB)加入量、CTMAB溶液浓度和吸附时间对CTMAB吸附量的影响 .测得加工后的膨润土对CTMAB的饱和吸附容量为 34 0 0± 30 0mg·1 0 0g- 1膨润土 .膨润土对CTMAB的吸附表现出Lang muir吸附特征 .6 0℃ ,当CTMAB的加入量为膨润土饱和吸附容量的 1 3— 1 5倍 ,CTMAB溶液浓度≥ 2mg·ml- 1,吸附时间超过 2 0h时 ,膨润土基本达到饱和吸附 .并考察了有机膨润土对于水中苯、甲苯、乙苯、邻二甲苯 (BTEX)的去除效果 .     

BTEX在乙醇汽油和传统汽油污染地下水中的衰减行为对比

地下燃油储藏罐泄漏造成苯、甲苯、乙苯和二甲苯（BTEX）影响生态环境和公众健康的问题一直备受关注,随着乙醇汽油的推广使用,乙醇对BTEX修复策略的影响成为需要重视的新问题.为揭示乙醇汽油污染地下水中BTEX的衰减行为,本文通过室内两个独立砂槽投注实验和近3年的监测,对比了乙醇汽油和传统汽油中BTEX自然衰减和基于硫酸盐-硝酸盐补充的增强生物修复行为.结果表明,传统汽油BTEX自然衰减较快,乙醇汽油BTEX自然衰减较慢,一级衰减速率常数分别为0.0055~0.0329 d^-1和0.0045~0.0124 d^-1;苯衰减最快,其次为甲苯.补充硫酸盐和硝酸盐能促进生物修复,单独补充硫酸盐时其利用率为89.7%~92.9%,同时补充硝酸盐时硫酸盐利用被抑制,硝酸盐利用率为79.9%~87.2%.水位波动会促进BTEX溶解和迁移,增大质量通量.乙醇汽油不仅能消耗更多电子受体,使得BTEX衰减被抑制,而且可能会扩大水位波动引起的增溶效应.