我国主要河流中3种氯酚混合物的生态风险评价

氯酚类化合物是我国河流中广泛存在的一类优先控制污染物. 利用基于相似作用模式的混合物风险商（RQ_m）的方法,对我国主要河流中五氯酚、2,4-二氯酚和2,4,6-三氯酚组成的混合物进行了生态风险评价. 结果表明:我国河流中3种氯酚化合物的RQ_m均小于1. 黄河中3种氯酚化合物的RQ_m最高为0.377,长江、珠江、淮河和松花江中3种氯酚化合物的RQ_m分别为0.055、0.039、0.035和0.010,其他河流的RQ_m均小于0010. 整体上看,我国北部河流3种氯酚化合物的RQ_m比南部河流高.      

Effect of the chemical composition of organic extracts from environmental and industrial atmospheric samples on the genotoxicity of polycyclic aromatic hydrocarbons mixtures

Particulate organic matter (PM) present in the atmosphere is a complex mixture of chemicals like polycyclic aromatic hydrocarbons (PAH) that may exert adverse health effects including respiratory and cardiovascular disturbances and cancer. In this study, airborne samples from environmental or industrial areas exhibiting different physicochemical composition were compared for their capacities to induce DNA damage in human hepatocytes HepG2. DNA strand breaks and DNA adducts formed by benzo[a]pyrene-7,8-dihydrodiol-9,10-epoxide (BPDE), the most reactive metabolite of the carcinogenic benzo[a]pyrene (B[a]P), were measured with the comet assay and by high-performance liquid chromatography (HPLC)/mass spectrometry, respectively. Cells were exposed to organic matter extracted from PM. Experiments were performed either at a constant concentration of B[a]P or at concentrations corresponding to fixed air volumes. Results show that industrial extracts tend to produce more benzo[a]pyrene diol epoxide-N ²-2′-deoxyguanosine (BPDE-N ²-dGuo) DNA adducts than strand breaks, whereas the opposite was observed with environmental extracts. The chemical composition of the extracts significantly impacts the nature and levels of DNA damage. The amount of B[a]P and interaction with other contaminants in the extracts need to be considered to explain the formation of DNA damage. These results emphasize the use of in vitro tests as promising and complementary tools to widely used toxic equivalent factor (TEF) approach in order to assess health hazards related to chemical exposure of the general population.     

A comparison of two methods to observe the effects of dual metal exposure to the chironomus larvae

A study was conducted to investigate the effects of metal mixtures on the Chironomus plumosus. Two methods of preparing the mixtures were used, the Toxic Unit (TU) method and the parts per million (PPM) + PPM method. A comparison was undertaken between the two methods to observe the ease with which (1) experiment could be conducted and (2) whether LC₅₀ values could be obtained. In this study, it was noted that the PPM + PPM method was an easier method to conduct metal mixture experiments as the LC₅₀ values could be easily calculated for individual metals and compared with the LC₅₀ values of metals obtained from single metal experiments. The findings showed that the LC₅₀ value for zinc (Zn) was more toxic for chromium (Cr) when it was reduced from 9.6 to 0.3 mg L^?1, with silver the LC₅₀ value became 3.6 mg L^?1, 4.5 mg L^?1 with nickel (Ni). In the PPM + PPM method, the LC₅₀ value for Zn was observed to be 10.2 mg L^?1 when in mixture with chromium, 23.8 mg L^?1 with silver, and 13.4 mg L^?1 with Ni. Changes in the 96 h LC₅₀ value were found to be significant for all metals.     

Experimental research on the flammability characteristics of several binary blends consisting of 1-Chloro-1,1-difluoroethane and extinguishing agents

1-Chloro-1,1-difluoroethane (R142b) can be used as the refrigerant, foaming agent and ORC (Organic Rankine Cycle) fluid. R142b was described as one of the interim substitutes in the Montreal Protocol (signed in 1987), and allowed to be used in developing countries until 2040. However the production and consumption of R142b were required to be frozen this year on the average data of 2009 and 2010 according to its latest amendment (signed in 2007). Binary alternatives R245fa/R142b, R227ea/R142b, R600a/R142b and R134a/R142b are possible substitutes in the initial transition period of frozen and phase-out R142b for the reason of pressure approach, which may be welcomed by the countries with wide use of R142b considering the technology and cost. This paper contributes to the flammability of these binary mixtures experimentally by using a self-made test rig built on the ground of Chinese National Standard. Not only the flammable limits of blends were studied, but also the related flame images were presented and analyzed. In addition, the flame suppression efficiencies of R245fa, R227ea and R134a have been compared and the lower flammable limits of R600a/R142b has been estimated and tested at different ratios. The presented work is beneficial to environmental protection.     

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。     

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。     

Low rate releases of hazardous light gases under semi-confined geometry: A consequence based approach and case-study application

As evidenced by accident statistics, an important factor when considering the safe operation of process plants is the effective mitigation of the effects of gaseous flammable releases, either by a prevention, or a protection approach. A detailed historical analysis was performed considering accidental scenarios associated with the use and management of light gases, starting from raw data selected from FACTS database and analysed by a causal multi-layer method. Results revealed that the major part of the accidental releases involving methane, hydrogen, ethene, ammonia can be attributed to organizational or process/plant immediate causes. As expected, the most frequent scenarios following the release are fire and explosion. We focus our attention on the development of a short-cut method allowing preliminary evaluation of the maximum gaseous build-up under semi-confined conditions, limiting the effects of the fire/explosion scenario to a tolerable level. The limitations of the model that is applied to selected case-studies and require further experimental validation are critically discussed. The results of the application of the model, which can boast of being safe but not disproportionately conservative, can be set as a maximum threshold in proper designing technical measures aiming at limiting the effects to a tolerable level by protection methods, e.g. isolation, venting, suppression and containment.     

Ecotoxicity in Aliivibrio fischeri of Ibuprofen,Omeprazole and their Mixtures

The acute ecotoxic effects of ibuprofen and omeprazole and their mixture have been measured using Aliivibrio fischeri as a biomodel. The toxic effects were also tested after 5 days, and an effect-driven approach was used to analyse the results. The toxic effects of the mixtures were compared with the predictions obtained using concentration addition and independent action mathematical methods.

According to the Passino and Smith classification, the results indicate that ibuprofen can be considered slightly toxic (10<EC₅₀ <100?mg?L^-1), while omeprazole can be denoted as moderately toxic (1<EC₅₀ <10?mg?L^-1) to Aliivibrio fischeri. An overestimation of the actual ecotoxic effect of the mixture was found when the concentration addition and independent action methods were applied. Finally, the effect-driven approach indicated that the transformation products of the studied drugs should be prioritized for risk assessment purposes.     

Soil effects of six different two-species litter mixtures that include Ulmus pumila

The tree species that contribute to decomposed leaf litter can have important effects on soil properties and thus nutrient cycling and interactions between tree species. We examined ground leaf litter and soil mixtures consisting of leaves from Ulmus pumila (Up) combined individually with leaves from one of six other species: Betula platyphylla (Bp), Quercus liaotungensis (Ql), Salix matsudana (Sm), Hippophae rhamnoides (Hr), Caragana microphylla (Cm), and Amorpha fruticosa (Af). The soil–litter mixtures were incubated for 120 days to analyse the effects of their decomposition on soil properties and to determine the interactions between the different types of litter within each mixture. The decomposed litter mixtures were composed of Up combined with Sm- or Hr-improved soil fertility relative to the pure Up mixture, but the decomposed litter mixtures were composed of Up combined with Cm-, Af-, or Ql-diminished soil properties. Three leaf mixture treatments, namely Up?×?Bp, Up?×?Sm, and Up?×?Hr, exhibited synergistic effects on soil properties (i.e. soil properties exceeding the predicted values); however, three other treatments, namely Up?×?Ql, Up?×?Cm, and Up?×?Af, exhibited antagonistic effects (i.e. properties below the predicted values). Therefore, litter from Bp, Sm, or Hr should be mixed with Up to improve soil fertility and production in plantations.