Stable-isotope probing of bacterial community for dissolved inorganic carbon utilization in Microcystis aeruginosa-dominated eutrophic water

Dissolved inorganic carbon (DIC) is an important source of carbon in aquatic ecosystems, especially under conditions of increased frequency of cyanobacterial bloom. However, the importance of bacteria in direct or indirect utilization of DIC has been widely overlooked in eutrophic freshwater. To identify the functional bacteria that can actively utilize DIC in eutrophic freshwater during cyanobacterial bloom, stable-isotope probing (SIP) experiments were conducted on eutrophic river water with or without inoculation with cyanobacteria (Microcystis aeruginosa). Our 16S rRNA sequencing results revealed the significance of Betaproteobacteria, with similar relative abundance as Alphaproteobacteria, in the active assimilation of H¹³CO₃^? into their DNA directly or indirectly, which include autotrophic genera Betaproteobacterial ammonia-oxidizing bacteria. Other bacterial groups containing autotrophic members, e.g. Planctomycetes and Nitrospira, also presented higher abundance among free-living bacteria in water without cyanobacteria. Microcystis aggregates showed a preference for some specific bacterial members that may utilize H¹³CO₃^? metabolized by Microcystis as organic matter, e.g. Bacteroidetes (Cytophagales, Sphingobacteriales), and microcystin-degrading bacteria Betaproteobacteria (Paucibacter/Burkholderiaceae). This study provides some valuable information regarding the functional bacteria that can actively utilize DIC in eutrophic freshwater.     

垃圾处理园区周边土壤-地下水重金属分布特征

测定并分析生活垃圾综合处理园区周边剖面土壤-地下水中重金属（Cr、Cu、Ni、Pb、Zn、As、Cd和Hg）的含量结果表明,在土壤水的对流、扩散作用下重金属在各点位土壤剖面中均存在明显的纵向迁移现象,同时土壤介质的吸附、拦截等阻滞作用导致重金属主要富集于150~200cm中层土壤中.该区域土壤中重金属虽有积累但尚未超标,垃圾焚烧飞灰沉降导致上游点位土壤中重金属含量高于另外两个距离更近的下游点位;而园区邻近地下水中Zn、Ni含量相对其他远距离点位明显增加,且Zn含量超出了地下水质量标准,推测是由垃圾渗滤液下渗的影响所致.借助高通量测序手段分析发现,不同深度土壤及地下水之间的微生物群落结构存在显著差异（p<0.01）,由于还存在其他土壤环境要素的作用,土壤中大部分微生物群落受重金属影响较小,而地下水中微生物群落明显受到垃圾渗滤液中重金属Zn、Ni富集的影响.本研究可为垃圾综合处理园区的土壤-地下水系统污染风险评估奠定基础,为其环境安全管理提供科学指导.     

近36a来四川盆地持续霾事件特征及环流分析

利用1981~2016年四川盆地102个气象观测站逐日霾日观测资料,对四川盆地持续霾事件（定义为连续3d及以上有烟幕或霾发生的天气）的时空分布特征、变化趋势进行分析,然后对冬季霾事件环流场特征进行研究.结果表明：1981~2016年四川盆地持续霾事件的年平均日数呈增加趋势,持续霾事件日数占霾总日数的百分比与霾总日数增加趋势较为一致,霾总日数的增加主要是由持续霾事件的增加引起的.四川盆地持续霾事件的空间分布不均匀,与霾日数的大值区的分布较为一致,主要集中在川东北城市群、成都平原城市群以及川南城市群.持续霾事件多发区的范围在1981~2010年呈年代际增大,在2011~2016年范围减少显著.通过分析盆地冬季霾事件的环流场发现,霾事件偏多（少）年时段,四川盆地处于暖（冷）高（低）压大值区域,乌拉尔山阻塞高压偏弱（强）,东亚大槽偏弱（强）,盆地上空为一定程度的辐合（辐散）,存在（不存在）明显逆温结构,垂直上升运动弱（强）,这些条件均有利于污染物颗粒聚集在浅薄的边界层内（利于污染物的扩散）,造成霾天气的维持（消散）.     

南京、新沂地震台地电地磁同场观测对地磁干扰的改善

根据南京地震台一系列地电地磁同场观测时对地磁干扰的研究试验结果,南京地震台在新地电场地建设和新沂地震台在地电外线路的改造中,都注意使供电线路的“单线段”远离地磁观测室,使地电对地磁的干扰得到了明显的改善。     

镍的环境生物地球化学与毒性效应研究进展

目前镍的毒性评价大多基于单一指标和室内控制实验研究,如何综合考虑镍在水环境中的形态及天然复合水化学条件的影响,进而准确预测水体中镍的生物毒性是水质基准及生态风险评估领域的难题.本研究结合国内外最新研究进展,对镍的来源、形态、生物有效性、毒性机理、水质基准和标准及污水处理工艺等进行归纳总结.重点围绕镍的环境行为和毒性效应展开,剖析了水化学因子对镍生物有效性的影响,概述了镍对不同营养级水生生物的毒性表现,总结出镍对淡水水生生物的六大毒性作用机理,展望镍的生物有效性对毒性效应的影响趋势,对我国镍的淡水水生生物水质基准的制定具有重要意义.     

Destructing surfactant network in nanoemulsions by positively charged magnetic nanorods to enhance oil-water separation

The separation of ultrafine oil droplets from wasted nanoemulsions stabilized with high concentration of surfactants is precondition for oil reuse and the safe discharge of effluent. However, the double barriers of the interfacial film and network structures formed by surfactants in nanoemulsions significantly impede the oil-water separation. To destroy these surfactant protective layers, we proposed a newly-developed polyethyleneimine micelle template approach to achieve simultaneous surface charge manipulation and morphology transformation of magnetic nanospheres to magnetic nanorods. The results revealed that positively charged magnetic nanospheres exhibited limited separation performance of nanoemulsions, with a maximum chemical oxygen demand (COD) removal of 50%, whereas magnetic nanorods achieved more than 95% COD removal in less than 30 s. The magnetic nanorods were also applicable to wasted nanoemulsions from different sources and exhibited excellent resistance to wide pH changes. Owing to their unique one-dimensional structure, the interfacial dispersion of magnetic nanorods was significantly promoted, leading to the efficient capture of surfactants and widespread destruction of both the interfacial film and network structure, which facilitated droplet merging into the oil phase. The easy-to-prepare and easy-to-tune strategy in this study paves a feasible avenue to simultaneously tailor surface charge and morphology of magnetic nanoparticles, and reveals the huge potential of morphology manipulation for producing high-performance nanomaterials to be applied in complex interfacial interaction process. We believe that the newly-developed magnetic-nanorods significantly contribute to hazardous oily waste remediation and advances technology evolution toward problematic oil-pollution control.     

Effects of multi-phase inoculation on the fungal community related with the improvement of medicinal herbal residues composting

Environmental Science and Pollution Research - Composting has become the most important way to recycle medicinal herbal residues (MHRs). The traditional composting method, adding a microbial agent...     

The Relationships among Topographically-driven Habitats,Dominant Species and Vertical Layers in Temperate Forest in China

Russian Journal of Ecology - The relationships among topography, topographically-driven habitats, dominant species and vertical layers in forest ecosystem are often complicate. In this study, based...     

环境友好型金属切削液的性能研究

以油酸、二乙醇胺、硼酸、苯并三氮唑为主要原料,采用酯交换法制得油酸二乙醇酰胺硼酸酯、相转移法制得苯并三氮唑衍生物,合成一种复合有机硼酸酯,采用傅立叶红外光谱仪对合成产物进行表征。对由复合有机硼酸酯配制的水基切削液进行防锈、润滑及清洗性能的测试。结果表明:(1)以油酸、二乙醇胺、硼酸和苯并三氮唑为主要原料制备出的复合有机硼酸酯,经红外光谱仪的表征,证实合成工艺可行。(2)水基切削液的防腐蚀和防锈性能随着复合有机硼酸酯添加量的增加而改善,在较高温较长时间的持续工作环境下同样能保持良好的防锈性能。(3)当复合有机硼酸酯添加量为0.25%(质量分数)时,水基切削液在60℃、24h的缓蚀率达到了70%左右,35℃时的单片及叠片防锈试验合格,25℃下的表面张力为33.13×10-4 N/dm,润滑性能良好。