日照市夏季VOCs物种空间分布特征及其对臭氧生成的影响

2020年8月22～ 29日期间利用便携式声表面波气相色谱仪(GC-SAW)对日照市区的主要企业源、居民源和道路开展了在线采样分析,获得了大气中多种挥发性有机物(VOCs)的空间分布特征,并对主要组分的化学反应活性进行研究.结果 表明,日照市碳原子大于5的VOCs(VOCC＞5)主要以甲苯、正丙苯和正辛烷为主,且空间分...     

石油污染对土壤-植物系统的生态效应

伴随着石油的工业化生产和利用,石油污染已经成为一个严重的环境问题.本文从土壤、植物个体、植物群落与生态系统等层次对石油污染的生态效应进行了系统总结.含有多环芳烃(Polycyclic aromatic hydrocarbons,PAHs)、苯系物(Benzene、toluene、ethylbenzene和xylene,BTEX)等多种有毒物质的石油及其化工产品进入土壤-植物系统后会发生迁移.这不仅对土壤-植物系统的组成、结构、功能和服务产生影响,也会通过食物链危害人类健康.石油污染影响土壤水分状况、孔隙度等物理性质,土壤碳含量、养分含量等化学性质,以及土壤微生物群落组成和多样性、土壤酶活性等生物学性质.通常,石油污染会对大多数植物形成氧化胁迫,影响细胞膜透性,影响光合作用等生理活动,抑制植物生长,影响植物萌发、开花和结实.由于石油污染对植物个体的不同效应以及植物个体对石油污染的不同响应,石油污染对植物群落的影响存在3种基本模式,并最终导致植物群落生物量下降,物种多样性降低,植被盖度降低.进一步影响生态系统的生产力、稳定性和健康,最终危及生态系统的功能和服务.利用微生物、植物及其联合体菌根可以对石油污染物进行生物修复和降解,添加外源营养物质和通气等措施可以强化生物修复过程.应用植被指数和红边效应等遥感方法进行石油污染的生态效应监测具有较大的潜力.总之,如何把土壤-植物系统各水平上不同指标对石油污染物的响应与石油污染的生态效应联系起来,是目前石油污染生态效应研究的重点和难点之一.因此,亟需开展多尺度的系统研究,把室内控制实验、野外控制实验和野外调查有机地结合起来,构建多层次的石油污染标志物体系,全面认识石油污染对土壤-植物系统的生态效应,为石油污染的生态风险评价、治理和控制提供理论基础和实践指导.     

Construction and comparison of fluorescence and bioluminescence bacterial biosensors for the detection of bioavailable toluene and related compounds

Environmental pollution with petroleum products such as benzene, toluene, ethylbenzene, and xylenes (BTEX) has garnered increasing awareness because of its serious consequences for human health and the environment. We have constructed toluene bacterial biosensors comprised of two reporter genes, gfp and luxCDABE, characterized by green fluorescence and luminescence, respectively, and compared their abilities to detect bioavailable toluene and related compounds. The bacterial luminescence biosensor allowed faster and more-sensitive detection of toluene; the fluorescence biosensor strain was much more stable and thus more applicable for long-term exposure. Both luminescence and fluorescence biosensors were field-tested to measure the relative bioavailability of BTEX in contaminated groundwater and soil samples. The estimated BTEX concentrations determined by the luminescence and fluorescence bacterial biosensors were closely comparable to each other. Our results demonstrate that both bacterial luminescence and fluorescence biosensors are useful in determining the presence and the bioavailable fractions of BTEX in the environment.     

Bio-removal of mixture of benzene, toluene, ethylbenzene, and xylenes/total petroleum hydrocarbons/trichloroethylene from contaminated water

Four pure cultures were isolated from soil samples potentially contaminated with gasoline compounds either at a construction site near a gas station in Fai Chi Kei, Macau SAR or in the northern parts of China (Beijing, and Hebei and Shandong). The e ects of di erent concentrations of benzene, toluene, ethylbenzene, and three isomers (ortho-, meta-, and para-) of xylene (BTEX), total petroleum hydrocarbons (TPH), and trichloroethylene (TCE), when they were present in mixtures, on the bio-removal e ciencies of microbial isolates were investigated, together with their interactions during the bio-removal process. When the isolates were tested for the BTEX (50–350 mg/L)/TPH (2000 mg/L) mixture, BTEoX in BTEoX/TPH mixture was shown with higher bio-removal e ciencies, while BTEmX in BTEmX/TPH mixture was shown with the lowest, regardless of isolates. The TPH in BTEmX/TPH mixture, on the other hand, were generally shown with higher bio-removal e ciencies compared to when TPH mixed with BTEoX and BTEpX. When these BTEX mixtures (at 350 mg/L) were present with TCE (5–50 mg/L), the stimulatory e ect of TCE toward BTEoX bio-removal was observed for BTEoX/TCE mixture, while the inhibitory e ect of TCE toward BTEmX for BTEmX/TCE mixture. The bio-removal e ciency for TPH was shown lower in TPH (2000 mg/L)/TCE (5–50 mg/L) mixtures compared to TPH present alone, implying the inhibitory e ect of TCE toward TPH bio-removal. For the mixture of BTEX (417 mg/L), TPH (2000 mg/L) along with TCE (5– 50 mg/L), TCE was shown co-metabolically removed more e ciently at 15 mg/L, probably utilizing BTEX and/or TPH as primary substrates.     

大学校园室内BTEX浓度水平变化规律及健康风险

采用Tenax-TA吸附/热脱附-气相色谱法(TD-GC)对大学校园室内外空气中5种苯系物(BTEX,苯、甲苯、乙苯、间/对-二甲苯和邻二甲苯)的平均浓度进行了检测。检测结果显示,5种苯系物的平均浓度均低于国家标准值。被测空气的苯系物中甲苯所占比例最大,为27.9%～32.0%。室内BTEX浓度稍高于室外,多数采样点的室内浓度与室外浓度比值(CI/CO)大于1.0。通风可有效降低空气中苯系物浓度。大学校园室内空气中的苯对学生的致癌风险为3.67×10-7～1.09×10-6。     

不同动力公交流动微环境BTEX的浓度水平及健康风险

用热解析气相色谱法采集分析不同动力公交车微环境中苯系物,研究了江南某旅游城市公交汽油车、柴油车、电车、液化天然气车、油电混合车空气中苯系物的浓度以及主要公交站台的苯系物的浓度。结果表明,公交车微环境中苯系物平均浓度从高到低依次为汽油车>柴油车>油电混合车>液化天然气车>电车,其中汽油车苯含量最高,为(21.02±9.51)μg/m3,各动力公交车的苯暴露对公交司机致癌风险为2.32×10-6～4.79×10-6,超过了美国EPA制定的人体致癌风险限值。     

车辆限行前后奥运场馆附近空气中苯系物污染特征与来源

在"好运北京"体育赛事车辆限行前后对北京奥运场馆,即四环路健翔桥附近空气中的6种苯系物进行了连续监测。监测结果显示,被测空气的苯系物中甲苯所占比例最大,为32.1%~42.5%,限行后总苯系物平均质量浓度降低了近47%。车辆限行前后,苯系物呈现类似的日变化规律,在交通早、晚高峰时出现峰值。限行前苯系物处于累积状态,日最高值出现在18点,限行后苯系物处于扩散状态,日最高值出现在8点。苯系物来源解析表明,整个交通管制期间苯/甲苯浓度的比值为0.49~0.55,且各苯系物具有良好的相关性,证明被测空气中苯系物具有良好的同源性,均来自汽车尾气。限制车流量可有效降低空气中苯系物浓度。     

东北地区大气BTEX的时空分布特征

在东北地区7个典型城市中25个监测点进行了观测,时间分别为2008年4月、7月、10月和2009年1月,使用吸附剂采样管采集并通过热脱附-气相色谱-质谱联用技术分析了苯系物样品,系统研究了东北地区大气苯系物的时空分布特征。研究结果表明,苯和甲苯年均浓度值最高,分别为(4.19±2.31)μg/m3和(3.22±1.14)μg/m3,共占苯系物浓度近70%;各功能区按苯系物浓度大小顺序排列为混合区工业区交通区居民区文教区对照区;受排放源和气象条件的影响,采暖期苯系物浓度高于非采暖期苯系物浓度;风向频率影响苯系物浓度分布,沿下风向浓度逐渐降低;苯/甲苯比值分析表明,东北地区苯系物的主要来源是煤燃烧。