苯乙烯对几种海洋生物的急性毒性效应

在封闭静水式条件下,苯乙烯对小新月菱形藻和扁藻的96 hEC50分别为8.96 mg/L和5.94 mg/L.苯乙烯对甲壳动物和鱼类的实验采取开放静水式方法.中国对虾仔虾和中华绒螯蟹幼蟹的96 hLC50 分别为7.96 mg/L和72.27 mg/L,牙鲆的96 h LC50为18.55 mg/L.按新化学物质危害评估导则中的分级标准,苯乙烯对两种实验藻和中国对虾的毒性属高毒性,对中华绒螯蟹和牙鲆具有中毒性.计算出苯乙烯的无影响阈值(ENEV)为0.594 mg/L,可以为制定苯乙烯的水生生物安全阈值提供参考.     

大渡河流域川陕哲罗鲑分布与栖息地特征研究

在实地调查和资料分析基础上,对大渡河流域川陕哲罗鲑栖息地及分布进行了量化分析,并对其适宜栖息地保护河段进行了评估与划分。研究表明:(1)1950~2012年,大渡河流域川陕哲罗鲑分布范围持续减少,损失率高达91.4%,强烈的人类活动(如水电开发)成其主要影响因素;(2)川陕哲罗鲑对栖息地生境质量需求较高,适应水温范围较窄(4℃~14℃)。在不同生活史阶段川陕哲罗鲑对于生境的需求存在差异;(3)大渡河上游干流及众多支流对保护川陕哲罗鲑极为重要。在上游适宜划分为川陕哲罗鲑栖息地保护的河段总长度共计2 222.9 km。根据研究结果,我们建议:(1)川陕哲罗鲑栖息地有效保护,不仅应保护其现有分布区域,而且还应涵盖具有较高保护和恢复价值的历史分布和潜在分布空间;(2)尽快开展大渡河河源区川陕哲罗鲑栖息地保护相关规划和研究工作;(3)为协调流域保护和发展,建议建立完善生态补偿机制。     

Use of metal-reducing bacteria for bioremediation of soil contaminated with mixed organic and inorganic pollutants

Mixed contamination by organic and inorganic compounds in soil is a serious problem for remediation. Most laboratory studies and field-scale trials focused on individual contaminant in the past. For concurrent bioremediation by biodegradation and bioleaching processes, we tested metal-reducing microorganism, Geobacter metallireducens. In order to prove the feasibility of the coupled process, multiple-contaminated soil was prepared. Mineralogical analyses have shown the existence of labile forms of As(V) as amorphous and/or weakly sorbed phases in the secondary Fe oxides. In the biotic experiment using G. metallireducens, biodegradation of toluene and bioleaching of As by bacteria were observed simultaneously. Bacteria accelerated the degradation rate of toluene with reductive dissolution of Fe and co-dissolution of As. Although there have been many studies showing each individual process, we have shown here that the idea of concurrent microbial reaction is feasible. However, for the practical use as a remediation technology, more details and multilateral evaluations are required in future studies.

     

不同土地利用类型的地表特征参量的遥感反演研究——以猫跳河流域为例

利用2007年5月Lansat5 TM数据,运用单通道算法,基于全国遥感监测土地利用/覆盖分类体系,对贵州省猫跳河流域的地表特征参量进行了反演,得到不同土地利用类型下的典型地表特征参数值。在3种主要的土地利用类型中,林地的植被指数最高、地表温度最低,农田的植被指数最低而地表温度最高,草地介乎林地和农田之间。城镇建设用地主要表现为热岛效应,而水域则主要表现为地表温度（LST）和归一化植被指数（NDVI）的双低特征。进一步对二级土地利用类型的分析表明,由于结构、功能的不同,土地利用二级类在地表特征参量方面也表现出了有规律地变化。有助于深入认识不同土地利用类型的物理特征,可以丰富主要土地利用类型的影像分类的先验知识,有望将不同土地利用方式的生态环境效应研究推进一步     

Assessment of Bacterial Degradation of Aromatic Hydrocarbons in the Environment by Analysis of Stable Carbon Isotope Fractionation

¹³C/¹²C stable carbon isotope fractionation was used to assess biodegradation in contaminated aquifers with toluene as a model compound. Different strains of anaerobic bacteria (Thauera aromatica, Geobacter metallireducens, and the sulfate-reducing strain TRM1) showed consistent ¹³C/¹²C carbon isotope fractionation with fractionation factors between C = 1.0017 and 1.0018. In contrast, three cultures of aerobic organisms, using different mono- and dioxygenase enzyme systems to initiate toluene degradation, showed variable isotope fractionation factors of C = 1.0027 (Pseudomonasputida strain mt-2), C = 1.0011 (Ralstonia picketii), andC = 1.0004 (Pseudomonas putida strain F1). The great variability of isotope fractionation between different aerobic bacterial strains suggests that interpretation of isotope data in oxic habitats can only be qualitative. A soil column was run as a model system for contaminated aquifers with toluene as the carbon source and sulfate as the electron acceptor and samples were taken at different ports along the column. Microbial toluene degradation was calculated based on the ¹³C/¹²C isotope fractionation factors of the batch culture experiments together with the observed ¹³C/¹²C isotope shifts of the residual toluene fractions. The calculated percentage of biodegradation, B, correlated well with the decreasing toluene concentrations at the sampling ports and indicated the increasing extent of biodegradation along the column. The theoretical toluene concentrations as calculated based on the isotope values matched the measured concentrations at the different sampling ports indicating that the Rayleigh equation can be used to calculate biodegradation in quasi closed systems based on measured isotope shifts. A similar attempt was performed to assess toluene degradation in a contaminated, anoxic aquifer. A transect of groundwater wells was monitored along the main direction of the groundwater flow and revealed decreasing concentrations accompanied with an increase in the ¹³C/¹²C stable carbon isotope ratio of the residual toluene. Calculation of the extent of biodegradation based on the isotope values and laboratory derived isotope fractionation factors showed that the residual toluene was degraded to more than 99% by microbial activity. Calculation of the theoretical residual toluene concentrations based on the measured isotope values described the strongly decreasing concentrations along the plume. Other aromatic hydrocarbons like benzene and naphthalene which were analysed in the same course also showed decreasing concentrations along the groundwater flow path accompanied by increasing ¹³C values indicating biodegradation.     

肉制品销售物流安全管理对策研究

21世纪以来 ,我国的肉制品产销量一直保持着强劲的增长势头 ,将成为居民的肉类消费主流。现阶段 ,国内肉制品物流的每一个环节都可能因温度变化、微生物侵蚀、有害物质污染等使肉制品对人体产生毒害 ,特别是肉制品销售物流安全直接关系广大消费者的利益。为此 ,在肉制品加工企业销售物流现场调研基础上 ,重点分析了肉制品销售物流过程中的安全隐患 ,并根据肉制品的产品特性和销售物流特性研究成果 ,提出肉制品销售物流的安全管理对策。     

光催化-臭氧协同处理微污染水体的研究

研究了利用光催化-臭氧协同处理微污染水体,分别考察了单一作用和协同作用、不同降解时间、pH值以及不同负载方式下的去除率。     

In situ biodegradation determined by carbon isotope fractionation of aromatic hydrocarbons in an anaerobic landfill leachate plume (Vejen,Denmark)

Concentrations and isotopic compositions (13C/12C) of aromatic hydrocarbons were determined in eight samples obtained from the strongly anoxic part of the leachate plume downgradient from the Vejen Landfill (Denmark), where methanogenic, sulfate-reducing and iron-reducing conditions were observed. Despite the heterogeneous distribution of the compounds in the plume, the isotope fractionation proved that ethylbenzene and m/p-xylene were subject to significant biodegradation within the strongly anoxic plume. The isotope fractionation factors (alphaC) for the degradation of the m/p-xylene (1.0015) and ethylbenzene (1.0021) obtained from the field observations were similar to factors previously determined for the anaerobic degradation of toluene and o-xylene in laboratory experiments, and suggest that in situ biodegradation is one major process controlling the fate of these contaminants in this aquifer. The isotope fractionation determined for 1,2,4-trimethylbenzene and 2-ethyltoluene suggested in situ biodegradation; however, the isotopic composition did not correlate well with the respective concentration as expressed by the Rayleigh equation. Some other compounds (1,2,3-trimethylbenzene, o-xylene, naphthalene and fenchone) did not show significant enrichments in delta13C values along the flow path. The compound concentrations were too low for accurate isotope analyses of benzene, toluene, 1- and 2-methylnaphthalene, while interferences in the chromatography made it impossible to evaluate the isotopic composition for 4-ethyltoluene, 1,3,5-trimethylbenzene and camphor.In addition to demonstrating the potential of assessing isotopic fractionation as a means for documenting the in situ biodegradation of complex mixtures of aromatic hydrocarbons in leachate plumes, this study also illustrates the difficulties for data interpretation in complex plumes and high analytical uncertainties for isotope analysis of organic compounds in low concentration ranges.     

Stable isotope fractionation analysis as a tool to monitor biodegradation in contaminated acquifers

The assessment of biodegradation in contaminated aquifers has become an issue of increasing importance in the recent years. To some extent, this can be related to the acceptance of intrinsic bioremediation or monitored natural attenuation as a means to manage contaminated sites. Among the few existing methods to detect biodegradation in the subsurface, stable isotope fractionation analysis (SIFA) is one of the most promising approaches which is pronounced by the drastically increasing number of applications. This review covers the recent laboratory and field studies assessing biodegradation of contaminants via stable isotope analysis. Stable isotope enrichment factors have been found that vary from no fractionation for dioxygenase reactions converting aromatic hydrocarbons over moderate fractionation by monooxygenase reactions (epsilon=-3 per thousand) and some anaerobic studies on microbial degradation of aromatic hydrocarbons (epsilon=-1.7 per thousand) to larger fractionations by anaerobic dehalogenation reactions of chlorinated solvents (epsilon=between -5 per thousand and -30 per thousand). The different isotope enrichment factors can be related to the respective biochemical reactions. Based on that knowledge, we discuss under what circumstances SIFA can be used for a qualitative or even a quantitative assessment of biodegradation in the environment. In a steadily increasing number of cases, it was possible to explain biodegradation processes in the field based on isotope enrichment factors obtained from laboratory experiments with pure cultures and measured isotope values from the field. The review will focus on the aerobic and anaerobic degradation of aromatic hydrocarbons and chlorinated solvents as the major contaminants of groundwater. Advances in the instrumental development for stable isotope analysis are only mentioned if it is important for the understanding of the application.     

环境内分泌干扰物促进乳腺细胞增殖的分子机制研究进展

乳腺癌是女性中常见的癌症,EDCs（environmental endocrine disrupting chemicals,环境内分泌干扰物）具有雌激素活性,能促进乳腺细胞的增殖,明确EDCs在乳腺癌细胞增殖中的作用和机制,有助于乳腺癌的预防.在归纳整理国内外相关研究基础上,总结了EDCs通过激活雌激素受体信号通路、抑制细胞凋亡和改变细胞周期等方面促进乳腺细胞的增殖,并对其分子机制进行了全面综述.EDCs促进乳腺细胞增殖的分子机制有:①EDCs通过与雌激素核受体（nERs）结合形成二聚体,改变受体构象,并结合到靶基因雌激素响应元件（ERE）上,进而调控增殖相关靶基因转录和蛋白表达;②EDCs也可通过与雌激素膜受体（mERs）结合,激活快速非基因组信号通路,改变靶蛋白活性或靶基因表达;③EDCs也可通过上调凋亡抑制蛋白Bcl-2和Bcl-xL的表达,抑制细胞凋亡;④EDCs还可通过上调细胞周期蛋白（cyclin）表达、提高周期依赖性蛋白激酶（CDKs）活性,加快细胞周期;⑤EDCs通过基因组、非基因组信号途径的交互,上调cyclin D和c-Myc表达,再通过CDK磷酸化细胞周期调节因子Rb蛋白,释放转录因子E2Fs,加速细胞从G₁期向S期的转变,促进细胞增殖.建议今后从与内源激素交互、影响雌激素E₂合成以及低剂量联合作用3个方面来探讨EDCs对乳腺细胞的增殖机制,以期为乳腺致癌物的筛查、乳腺癌预防和治疗以及乳腺细胞增殖机制的深入研究提供参考.