拓展等效线图法评估离子液体与杀菌剂多果定之间的拮抗作用

等效线图法(isobologram)是评估化学混合物毒性相互作用的经典方法之一,然而该方法仅能评估混合物在某一特殊浓度效应水平(通常为50%的浓度效应水平,即EC50)的联合毒性作用情况。因此,拓展等效线图法并用于不同效应水平下混合物毒性的评估显得尤为必要。以杀菌剂多果定(Dod)和3种离子液体(ILs)包括溴化丁基吡啶([bpy]Br)、溴化己基吡啶([hpy]Br)和溴化辛基吡啶([opy]Br)为混合物组分,采用直线均分射线法设计3组二元混合物体系(Dod-[bpy]Br、Dod-[hpy]Br和Dod-[opy]Br)共15条射线,应用微板毒性分析法系统测定各污染物及其混合物射线对青海弧菌Q67(Vibro qinghaisiense sp. Q67,Q67)的毒性,应用拓展等效线图法分析15条混合物射线在5个不同效应水平(EC20、EC30、EC40、EC50和EC60)的毒性相互作用,并与经典等效线图法和浓度加和模型(CA)评估的结果进行比较。结果表明:以p EC50为毒性指标,3种吡啶ILs对Q67的毒性具有烷基链效应,即毒性大小顺序为Dod-[opy]BrDod-[hpy]BrDod-[bpy]Br; 3组二元混合物体系的15条射线的毒性,随农药Dod浓度比的减少而减弱;拓展等效线图法可以比较直观地表征3组Dod-ILs混合物体系在5个不同效应水平的拮抗作用,且拮抗作用强度随Dod浓度比的增加而变化,即先增强后减弱;拓展等效线图法可以有效地评估二元混合物在多个效应水平的联合毒性相互作用。     

Development of a new hydrocarbon index for oil-in-water

A new robust method for determination of hydrocarbons in water without use of Freon^™ or other halogenated solvents has been validated and subjected to an interlaboratory exercise. The method is based on extraction with a light hydrocarbon (boiling point in the 39–69°C range), followed by cleanup for removal of polar components and detection by gas chromatography (GC) with flame ionisation (FID) detection. The performance characteristics of the method are comparable with that of the previous Freon-IR method with recoveries in the 60–80% range and reproducibility (between laboratory variations) of about 30%.

A screening method for hydrocarbons in the range 5 ppm and above based on infrared spectroscopy (IR), and a promising method for detection of low levels based on solid phase extraction (SPE) has been tested and validated.     

酒精蒸气/烟草粉尘两相混合体系最小点火能试验研究

在烟草加工的加香工序,挥发的酒精和搅拌混料产生的烟草粉尘形成气粉混合体系,其燃爆特性相较于单相烟草粉尘有较大变化。对20 L爆炸球进行了部分改造,可完成20℃～80℃环境温度、100%LEL以下酒精蒸气浓度、最大2 J电火花能量组合的气粉混合物的最小点火能测试。选用烘丝和加香烟草粉尘做对比,探究了环境温度和酒精蒸气浓度对酒精蒸气/烟草粉尘两相混合体系点火能的影响规律。结果表明：相同环境温度下,加香烟草粉尘的最小点火能比烘丝烟草粉尘低;加香粉尘、烘丝粉尘及混合体系的最小点火能随环境温度变化的趋势一致,均随温度的升高而降低;加入10%LEL的酒精蒸气后,相同温度下气粉混合体系的最小点火能低于单相烟草粉尘。随着环境温度的升高,二者的差值逐渐减小,酒精蒸气诱导烟草粉尘最小点火能降低的能力逐步减小甚至消失;在电点火条件下,当酒精蒸气浓度低于50%LEL时,气粉混合体系较难被点燃,当酒精蒸气浓度高于75%LEL时,混合体系较易被点燃。     

Hazard analysis on LPG fireball of road tanker BLEVE based on CFD simulation

In order to research the hydrocarbon fireball characteristic of LPG tanker Boiled Liquid Evaporate Vapor Explosion (BLEVE) under different conditions, computational fluid dynamics (CFD) simulations of the hydrocarbon fireballs from the LPG tanker BLEVE accidents were carried out. Several new different factors, such as the mass of fuel, inlet velocity and airflow velocity, were considered to analyze the influence on the evolution of the characteristics of the fireball and the development of the LPG tanker BLEVE accidents. Results indicate that the fireball with a greater mass of fuel radiates more heat but slower. The large longitudinal diameter of the fireball and high radiation heat flux are observed in case of a faster inlet velocity used for the same mass. The airflow was found to shorten the initial phase of the fireball effectively. Some suggestions were proposed to prevent the LPG BLEVE accidents. Analysis performed show that various parameters like fireball diameter, radiative heat flux and lifting speed of fireball can be predicted well using FDS code.     

Change of magnetic properties due to fluctuations of hydrocarbon contaminated groundwater in unconsolidated sediments

Sediments affected by fluctuations of hydrocarbon contaminated groundwater were studied at a former military site. Due to remediation, groundwater table fluctuation (GWTF) extends over approximately one meter. Three cores were collected, penetrating through the GWTF zone. Magnetic parameters, sediment properties and hydrocarbon content were measured. We discovered that magnetic concentration parameters increased towards the top of the GWTF zone. Magnetite is responsible for this enhancement; rock magnetic parameters indicate that the newly formed magnetite is in a single domain rather than a superparamagnetic state. The presence of hydrocarbons is apparently essential for magnetite to form, as there is clearly less magnetic enhancement in the core, which is outside of the strongly contaminated area. From our results we conclude that the top of the fluctuation zone has the most intensive geomicrobiological activity probably responsible for magnetite formation. This finding could be relevant for developing methods for simply and quickly detecting oil spills.     

Temporal trends of hydrocarbons in sediment cores from the Pearl River Estuary and the northern South China Sea

Concentrations and fluxes of unresolved complex mixture of hydrocarbons (UCM) and polycyclic aromatic hydrocarbons (PAHs) were analyzed for two ²¹⁰Pb dated sediment cores from the Pearl River Estuary (PRE) and the adjacent northern South China Sea (NSCS). Compound-specific stable carbon isotopic compositions of individual n-alkanes were also measured for identification of the hydrocarbon sources. The historical records of PAHs in the NSCS reflected the economic development in the Pearl River Delta during the 20th century. PAHs in the NSCS predominantly derive from combustion of coal and biomass, whereas PAHs in the PRE are a mixture of petrogenic and pyrogenic in origins. The isotopic profiles reveal that the petrogenic hydrocarbons in the PRE originate predominantly from local spillage/leakage of lube oil and crude oils. The accumulation rates of pyrogenic PAHs have significantly increased, whereas UCM accumulation has slightly declined in the NSCS in the recent three decades.     

北京地区大气中非甲烷碳氢化合物（NMHC）的人为源排放特征研究

以能源为线索,运用气相色谱－质谱－计算机联用手段,对北京地区大气中各人为源排放的NMHC进行了分类定量测定。在此基础上分析了石油化工、交通、燃煤和居民液化石油气NMHC的排放特征及对北京地区大气NMHC的贡献。结果表明,交通运输和石油化工是对大气中NMHC贡献最大的人为源,其次是燃煤工业。对大气中NMHC的特征物种也进行了尝试性的研究。     

The origin of the chemical profiles of fungal symbionts and their significance for nestmate recognition in <Emphasis Type="Italic">Acromyrmex</Emphasis> leaf-cutting ants

Cuticular hydrocarbon profiles are essential for nestmate recognition in insect societies, and quantitative variation in these recognition cues is both environmentally and genetically determined. Environmental cues are normally derived from food or nest material, but an exceptional situation may exist in the fungus-growing ants where the symbiotic fungus garden may be an independent source of recognition compounds. To investigate this hypothesis, we quantified the chemical profiles of the fungal symbionts of 18 sympatric colonies of Acromyrmex echinatior and Acromyrmex octospinosus and evaluated the quantitative variation of the 47 compounds in a multivariate analysis. Colony-specific chemical profiles of fungal symbionts were highly distinct and significantly different between the two ant species. We also estimated the relative genetic distances between the fungal symbionts using amplified fragment length polymorphism (AFLP) and correlated these with the overall (Mahalanobis) chemical distances between the colony-specific profiles. Despite the standardized laboratory conditions, the correlations were generally weak, but a statistically significant portion of the total variation in chemical profiles could be explained by genetic differences between the fungal symbionts. However, there was no significant effect of ant species in partial analyses because genetic differences between symbionts tend to coincide with being reared by different ant species. However, compound groups differed significantly with amides, aldehydes, and methyl esters contributing to the correlations, but acetates, alkanes, and formates being unrelated to genetic variation among symbionts. We show experimentally that workers that are previously exposed to and fed with the fungal symbiont of another colony are met with less aggression when they are later introduced into that colony. It appears, therefore, that fungus gardens are an independent and significant source of chemical compounds, potentially contributing a richer and more abundant blend of recognition cues to the colony “gestalt” than the innate chemical profile of the ants alone. Freddie-Jeanne Richard and Michael Poulsen contributed equally to this work.     

The co-application of earthworms (Dendrobaena veneta) and compost to increase hydrocarbon losses from diesel contaminated soils

The feasibility of using composted civic waste for the remediation of a soil contaminated with petroleum hydrocarbons (extractable petroleum hydrocarbons (EPH) 10+/-1.8 g kg(-1) and total 16 USEPA PAH 1.62+/-0.5 g kg(-1)) was assessed. The effects of compost to soil ratio, in combination with and without earthworm presence (Dendrobaena veneta), upon the loss of contaminants were determined for EPH (GC-FID) and PAH (GC-MS), respectively. Increasing the ratio of compost substrate to hydrocarbon impacted soil (1:0.5, 1:1, 1:2 and 1:4 (soil:compost wt/wt)) in the absence of earthworms resulted in significantly (p<0.05) greater losses of both EPH and SigmaPAH after an 84 d incubation period, when compared to the soil only control. Where earthworms were present without compost, EPH losses were significantly (p<0.05) enhanced in the soil only treatment (33.4+/-5.3% residual) compared to the soil only control (54.4+/-5.3% residual). However, PAH loss in the soil only treatment (with-earthworm presence) were only slightly enhanced (65.3+/-9.3% residual), with respect to the soil only control (69.2+/-6.4% residual). Synergistic benefits of both earthworm and compost presence were most significant for PAHs (p<0.05), and less so for EPH. (14)C-respirometer studies, to establish catabolic competence in terms of microbial mineralisation of key hydrocarbons, complemented the hydrocarbon analysis.     

Efficiency in hydrocarbon degradation and biosurfactant production by Joostella sp. A8 when grown in pure culture and consortia

Joostella strains are emerging candidates for biosurfactant production. Here such ability was analyzed for Joostella strain A8 in comparison with Alcanivorax strain A53 and Pseudomonas strain A6, all previously isolated from hydrocarbon enrichment cultures made of polychaete homogenates. In pure cultures Joostella sp. A8 showed the highest stable emulsion percentage(78.33%), hydrophobicity rate(62.67%), and an optimal surface tension reduction during growth in mineral medium supplemented with diesel oil(reduction of about 12 mN/m), thus proving to be highly competitive with Alcanivorax and Pseudomonas strains. During growth in pure culture different level of biodegradation were detected for Alcanivorax strain A53(52.7%),Pseudomonas strain A6(38.2%) and Joostella strain A8(26.8%). When growing in consortia,isolates achieved similar abundance values, with the best efficiency that was observed for the Joostella-Pseudomonas co-culture. Gas-chromatographic analysis revealed an increase in the biodegradation efficiency in co-cultures(about 90%), suggesting that the contemporary action of different bacterial species could improve the process. Results were useful to compare the efficiencies of well-known biosurfactant producers(i.e. Pseudomonas and Alcanivorax representatives) with a still unknown biosurfactant producer, i.e. Joostella, and to confirm them as optimal biosurfactant-producing candidates.