Persistence of methyl <Emphasis Type="Italic">tertiary</Emphasis> butyl ether (MTBE) against metabolism by Danish vegetation

BACKGROUND: Methyl tertiary butyl ether (MTBE) is the second most highly produced industrial chemical in the US and a frequent groundwater pollutant. At the same time, MTBE is quite persistent to biotic and abiotic decomposition. The goal of this study was to find plant species that could degrade MTBE and might be used in phytoremediation. METHODS: Excised roots and leaves (0.3 g) from more than 24 Danish plant species out of 15 families were kept in glass vessels with 25 ml spiked aqueous solution for 2 to 4 days. MTBE concentrations were 1 to 5 mg/L. Samples were taken directly from the solution with a needle and injected to a purge and trap unit. MTBE and the main metabolite, TBA, were measured by GC/FID. RESULTS AND DISCUSSION: Solutions with roots of poplar (Populus robusta) and a willow hybrid (Salix viminalis x schwerinii) produced TBA in trace amounts, probably stemming from bacteria. Significant MTBE reduction (> 10%) was not observed in any of the tests. Leaves from none of the species (trees, grasses and herbs) reduced the concentration of MTBE in the solution and no TBA, nor any other known metabolite of MTBE, was detected. CONCLUSION: It was not possible to find plants capable of efficiently degrading MTBE. This gives rise to the conclusion that plants probably cannot degrade MTBE at all, or only very slowly. RECOMMENDATIONS AND OUTLOOK: For phytoremediation projects, this has, as consequence, that the volatilization by plants (except with genetically engineered plants) is the only relevant removal process for MTBE. For risk assessment of MTBE, degradation by the plant empire is not a relevant sink process.     

2,4,4'-三溴联苯醚的光降解研究

以固相微萃取(SPME)结合气相色谱(GC)、气相色谱-质谱联用(GC/MS)技术作为分析检测手段,研究光源、有机溶剂、无机盐与腐殖酸对BDE-28光降解的影响,实验结果表明,光源是影响其降解的主要因素,其次,丙酮、铜离子和腐殖酸对其降解的影响较显著.光源对BDE-28光降解速率的影响为300 W汞灯500 W金卤灯100 W汞灯500 W氙灯;有机溶剂对BDE-28降解速率的影响为甲醇/水(1∶1)甲醇己烷甲苯乙腈丙酮;无机离子的影响各有差别:K+、Na+、SO2-4、NO-3、Cl-对BDE-28降解影响不明显,而Fe3+、NH+4促进BDE-28的降解,Fe2+、Cu2+、Br-抑制BDE-28的降解;腐殖酸抑制BDE-28的降解.     

Is BDE-175 an important enough component of commercial octabromodiphenyl ether mixtures to be listed in Annex A of the Stockholm Convention?

Commercial octabromodiphenyl ether mixtures, containing hexabromodiphenyl ethers and heptabromodiphenyl ethers were listed in Annex A of the Stockholm Convention on May 2009 (Fourth Conference of the Parties) (UNEP, 2009a). Four compounds are specifically mentioned: 2,2′,4,4′,5,5′-hexabromodiphenyl ether (BDE-153), 2,2′,4,4′,5,6′-hexabromodiphenyl ether (BDE-154), 2,2′,3,3′,4,5′,6-heptabromodiphenyl ether (BDE-175), and 2,2′,3,4,4′,5′,6-heptabromodiphenyl ether (BDE-183). Presumably they were identified as key components of commercial mixtures and found to be present in environmental samples. However, since BDE-175 and BDE-183 co-elute on common HRGC columns, the presence of BDE-175 as an important component in technical octa-BDE mixtures has not been illustrated. The successful HRGC/LRMS separation of a 1:1 mixture of BDE-175 and BDE-183, as well as ¹H NMR analysis of technical material, has allowed us to confirm that this congener is not present in technical products (e.g. Great Lakes DE-79™) in quantifiable amounts.     

Allometric models for the estimation of above- and below-ground biomass of Jatropha curcas L. in semi-arid regions of Southern India

Jatropha curcas L. (Jatropha) is an important multipurpose tree valued for oil. In India, plans are underway to bring substantial area under this crop for meeting the biofuel requirements of the country. A study was conducted to develop allometric relationships in Jatropha to predict various biomass-related components (above ground and below ground) using easily measurable attributes, viz. collar diameter, tree height, number of branches, crown diameter, and crown depth. Further, it was aimed to establish the reliability of these relationships using an independent dataset obtained from varied management situations. Destructive sampling was carried out during the rainy season of 2011, when Jatropha plants were eight years old. Highly significant allometric relationships (F-values significant at 1% level) were obtained while predicting various biomass components (above, below, and total) using easily measurable attributes with R² values ranging from 0.89 to 0.98. Of all the predictors, collar diameter exhibited a highly significant relationship with total dry biomass per plant (R² = 0.97). The allometric relationships developed were validated with an independent dataset. The allometric relationships developed would serve as valuable tools for estimating total dry biomass production and carbon sequestration with reasonable accuracy in Jatropha systems, as they are proposed to be taken up in substantial area in the years to come.     

直接固相微萃取气相色谱-质谱法测定辛基酚聚氧乙烯醚

建立了直接固相微萃取与气相色谱-质谱联用技术测定污水中辛基酚聚氧乙烯醚(OPEO_n)低聚物的方法.在最优实验条件下,测定辛基酚(OP)、辛基酚二乙氧醚(OPEO_2)、辛基酚三乙氧醚(OPEO_3)、辛基酚四乙氧醚(OPEO_4)、辛基酚五乙氧醚(OPEO_5)的线性范围分别为10～100,10-1 000,10～500,10～1 000,10～1 000 ng/L;检出限分别为10.4,7.7,8.1,9.0,8.5 ng/L;回收率为78.4%～114.0%,相对标准偏差小于10.4%.以正二十烷为内标,测定污水处理厂出水中的OPEO_n,实验结果表明,OPEO_2质量浓度高且变化范围较大,为133～2 412 ng/L.     

十溴联苯醚环境修复技术的研究进展

介绍了溴代阻燃剂十溴联苯醚（BDE-209）环境修复技术的研究进展。从光降解、零价铁降解、生物降解3个方面对BDE-209的降解机理和降解后的产物进行了介绍。BDE-209经光照、厌氧微生物、零价铁的脱溴作用后，降解成低溴代联苯醚产物；好氧微生物利用低溴代联苯醚作为生长碳源，将其在酶的作用下开环降解，进入三羧酸循环或彻底分解成CO₂和H₂O。提出应采用多种方法协同作用，更有效地降解多溴联苯醚化合物。     

Influence of foliar morphology and crown geometry on insecticide deposition and dissipation following an aerial spray over a mixed forest

Abstract

Deposition and dissipation of aerially sprayed phosphamidon insecticide over a mixed forest consisting of different species of coniferous and deciduous trees were studied. The data showed that the chemical deposited more and dissipated slower from deciduous foliage than from conifer needles. Differences in deposits and persistence were also found within each of the two foliar types. Leaf shape and orientation, crown geometry and foliar morphology appear to have played a role. No correlation was found between initial deposit levels and cuticular wax content of different foliar species. A controlled laboratory study showed that surface area/mass ratio played a more important role on initial deposits than pubescence/serrations present on foliar surfaces.     

电动力学作用下多溴联苯醚在土壤中的迁移特性

以4，4′-二溴联苯醚(BDE-15)为研究对象，探讨了电极电压、初始土壤pH、β-环糊精加入量、NaCl加入量等工艺条件对多溴联苯醚在土壤中迁移效果的影响。实验结果表明:在电极电压为5~15V范围内，随着电极电压的升高，土壤中BDE-15的迁移效果增强;初始土壤为酸性时、加入β-环糊精或NaCl后，土壤中BDE-15的迁移效果均增强。本实验选择的最佳工作条件为:电极电压15V，初始土壤pH3，β-环糊精的加入量3g，NaCl加入量5g。     

地下水浅埋区某加油站特征污染物空间分布

加油站渗漏污染地下水已经是一个世界性的问题。由于浅埋区加油站储罐与地下水密切接触，更加剧储罐的腐蚀。为揭示加油站渗漏的典型污染物石油烃（TPH）、苯系物（BTEX）、萘和甲基叔丁基醚（MTBE）在该水文地质条件下的迁移变化，在浅埋区某加油站开展了平、枯、丰水期的地下水监测工作。在水平分布上，TPH、BTEX、萘基本相似，均在加油岛附近形成高浓度区，而MTBE则更易随地下水流动而迁移，呈现出不同的污染晕。在垂直分布上，地下水的水位变动是污染物浓度分布的主要影响因素。     

沉积物中不同浓度多壁碳纳米管对Cd和BDE-47生态毒性的影响

随着碳纳米管的广泛应用,其将不可避免地进入环境中.由于其具有极好的吸附亲和力和吸附容量,碳纳米管可以充当环境中持久性有毒污染物的载体,从而改变共存污染物的生物有效性和生态毒性.为评价淡水沉积物中不同多壁碳纳米管(MWCNTs)对Cd和BDE-47生态毒性的影响,采用沉积物慢性生物测试研究了不同浓度MWCNTs存在下Cd和BDE-47对铜锈环棱螺肝胰脏抗氧化防御系统关键成分超氧化物歧化酶(SOD)与Ⅱ相解毒反应的关键酶谷胱甘肽-S-转移酶(GST)以及脂质过氧化损伤指标丙二醛(MDA)的影响.结果表明,沉积物中低浓度MWCNTs(0.5 mg·g~(-1))增强Cd对铜锈环棱螺的氧化胁迫,中、高浓度(5、50 mg·g~(-1))MWCNTs引起Cd对铜锈环棱螺的氧化损伤,MWCNTs的存在显著增强了沉积物中Cd对铜锈环棱螺的毒性,而且具有浓度-效应关系;低浓度MWCNTs不影响BDE-47对铜锈环棱螺的毒性,中、高浓度MWCNTs显著降低BDE-47的毒性,同样具有明显的浓度-效应关系.因此,在评价MWCNTs的潜在环境风险时,不仅考虑MWCNTs自身的毒性,还应当考虑MWCNTs的浓度、共存污染物的种类和MWCNTs与共存污染物之间的相互作用.