Microbial reduction of uranium (VI) by Bacillus sp. dwc-2: A macroscopic and spectroscopic study

The microbial reduction of U(VI) by Bacillus sp. dwc-2, isolated from soil in Southwest China, was explored using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge spectroscopy (XANES). Our studies indicated that approximately 16.0% of U(VI) at an initial concentration of 100 mg/L uranium nitrate could be reduced by Bacillus sp. dwc-2 at pH 8.2 under anaerobic conditions at room temperature. Additionally, natural organic matter (NOM) played an important role in enhancing the bioreduction of U(VI) by Bacillus sp. dwc-2. XPS results demonstrated that the uranium presented mixed valence states (U(VI) and U(IV)) after bioreduction, which was subsequently confirmed by XANES. Furthermore, the TEM and high resolution transmission electron microscopy (HRTEM) analysis suggested that the reduced uranium was bioaccumulated mainly within the cell and as a crystalline structure on the cell wall. These observations implied that the reduction of uranium may have a significant effect on its fate in the soil environment in which these bacterial strains occur.     

镍基催化剂对污泥微波热解制生物气效能的影响

为实现污水污泥减量化、无害化及资源化的目标,在微波热解污水污泥基础上,进行了镍基催化剂对制取生物气效能影响的研究。采用元素分析对污泥元素进行检测,气/质联用分析(GC-MS)和气相色谱(GC)对热解生物气的组成和含量进行测定。实验结果表明,镍基催化剂的添加对微波热解污水污泥制取生物气有较大促进作用。5%添加量与800℃热解终温条件下具有最佳催化效果:生物气中H2、CO产量最大,H2产量由29 g/kg增加到35.8 g/kg,提升23.4%,CO产量由302.7 g/kg增加到383.3 g/kg,提升26.6%;同时催化剂还能提高热能利用效率,降低热解终温,即5%添加量在700℃热解终温时可达到空白800℃时的产气效果;镍基催化剂主要在500~600℃时发挥催化作用,加快了H2和CO的释放。微波热解污泥制取的生物气具有产量大、富含H2与CO等优点,可推动污水污泥的资源化进程。     

家用空调碳足迹及其关键影响因素分析

我国居民家庭空调拥有量迅速增加,其生命周期中产生的温室效应也日益受到关注.本文依据国际标准PAS 2050,采用RCEES 2012和Ecoinvent 2.1数据库,并运用SimaPro 7.1软件计算了中国典型家用空调的碳足迹.主要结论为:家用空调生命周期中使用阶段用电产生的碳足迹最大,占67%;制冷剂的泄漏是除电力使用外第二大碳足迹贡献因素,产生了23%的碳足迹;生产制造阶段和废物处理阶段的碳足迹分别占16%和-6%.敏感性分析表明,空调日使用时间、空调年使用季节和制冷剂的泄漏比例是家用空调碳足迹的关键影响因素.     

基于高通量测序的SBR反应器丝状膨胀污泥菌群分析

为探究丝状污泥膨胀及控制过程中细菌菌群和真菌菌群的变化规律,采用一套11 L的SBR反应器,接种某城市污水处理厂膨胀污泥,以乙酸钠为碳源进行人工配水,对膨胀污泥进行399 d的培养实验,采用高通量测序技术对污泥样本进行菌群多样性分析.结果表明,接种污泥菌群多样性比较丰富,经培养至污泥高度膨胀后,菌群多样性降低,污泥沉降性能恢复正常后,菌群多样性又逐渐增加.细菌中的腐螺旋菌属(Saprospiraceae_norank)、丛毛单胞菌属(Comamonadaceae_unclassified)和四球菌属(Tetrasphaera)相对丰度分别为13.37%、10.54%和8.59%,是接种污泥的主要细菌属.经过培养,膨胀污泥菌群发生变化,接种污泥中细菌相对丰度仅为0.01%的丝硫菌属(Thiothrix)增加至56.95%~60.14%,真菌中相对丰度为19.60%的丝孢菌属(Trichosporon)增加至94.82%.污泥膨胀得到控制后,污泥中丝硫菌属(Thiothrix)相对丰度减少至0.01%,丝孢菌属(Trichosporon)相对丰度减少至2.32%.丝硫菌属(Thiothrix)和丝孢菌属(Trichosporon)过多不利于污泥沉降.     

T-2毒素的毒性效应及致毒机制研究进展

T-2毒素是由多种镰刀菌产生的单端孢霉烯族化合物中毒性较强的一种毒素,广泛存在于谷物和谷类食品中.经食物连续摄入T-2毒素会对人类和动物的健康造成潜在危害.目前,T-2毒素对人和动物健康的影响受到了社会的广泛关注,已成为毒理学领域研究的热点课题之一.在综述了T-2毒素的生物转化、代谢途径及其毒理学效应与机制基础上,对现...     

A method to extract algae toxin of microcystin-LR

A simple and low-cost method to obtain cyanobacterial toxin microcystin-LR(MC-LR) was developed. A new strain of Microcystis aeruginosa,named DC-1, producing microcystin-LR but not microcystin-RR, was separated from the field blooming algae samples of Dianchi Lake.in southwest of China. Following three times‘freeze and thaw treatment, the cultivated DC-cells were extracted with 40% methanol in water.The extract was centrifuged and the supernatant applied to a Hydrophilic-Lipophilic Balance(HLB) SPE cartridge.Eluted impuries with a certain gradient from 30% to 50% methanol in water, MC-LR was finally eluted from the HLB cartridge with 60%.may be used in adsorption and biodegradation experiments instead of using expensive standard reagents.     

生理毒代动力学模型及其在有机污染物水生生态毒理研究中的应用

人类生产和生活使用各种人工合成的化学品,种类和数量急剧增长,对生态系统和人体健康造成了极大威胁。因此,亟需采用高效的方法对数量巨大的化合物进行毒性评价。对生理毒代动力学(PBTK)模型的建立过程及其在污染物生态毒理研究中的应用进行了综述。PBTK模型,又称生理药代动力学(PBPK)模型,是利用生理学和解剖学等原理,将生物体简化为用血流连接的肝、肾和脂肪等各组织器官房室,模拟化合物在生物体内的吸收、分布、代谢和排泄过程。模型参数包括生理参数和生化参数2个部分,可用MATLAB等软件进行模拟。模型已应用于数百余种有机污染物在鱼体等水生生物体的毒代动力学模拟。已有模拟结果能够预测化合物在生物体内的有效剂量,对化合物毒性进行评估,并可用于不同物种、不同剂量和不同暴露途径间的外推,有力推进了污染物生态毒理研究工作的开展。     

Evidence on the causes of the rising levels of CODMn along the middle route of the South-to-North Diversion Project in China: The role of algal dissolved organic matter

As the biggest inter-basin water transfer scheme in the world,the South-to-North Water Diversion Project（SNWD） was designed to alleviate the water crisis in North China.The main channel of the middle route of the SNWD is of great concern in terms of the drinking water quality.In this study,we tested the hypothesis that the dissolved organic matter（DOM） derived from the planktonic algae causes the rising levels of COD_Mn along the middle route by monitoring data on water quality（2015-20...     

Hybrid zeolite-based ion-exchange and sulfur oxidizing denitrification for advanced slaughterhouse wastewater treatment

The discharge of slau ghterhouse wastewater（SWW） is incre asing and its wastewater has to be treated thoroughly to avoid the eutrophication.The hybrid zeolite-based ion-exchange and sulfur autotrophic denitrification（IX-AD） process was developed to advanced treat SWW after traditional secondary biological process.Compared with traditional sulfur oxidizing denitrification（SOD）,this study found that IX-AD column showed:（1） stronger ability to resist NO₃^-pollution load,（2） low...     

喀喇昆仑-昆仑山昆虫区系

喀喇昆仑-昆仑山昆虫区系属于典型的古北区性质,古北种占53.93％,中亚成分占16.85％,北坡受中亚成分影响大,南坡占有多数的高山成分。这一地域昆虫区系的形成和演替与其地质历史密切相关。由于印度板块不断向北挤压,喀喇昆仑-昆仑山强烈抬升,随着塔里木盆地的形成,地域性的昆虫区系便产生了,并有其特有成分的分化:亚种级的分化,种级的分化甚至属级的分化