Occurrence and risk evaluation of organophosphorus pesticides in typical water bodies of Beijing,China

Environmental Science and Pollution Research - Abstract Human activities, particularly in large cities, can lead to pollution caused by micropollutants such as pesticides in water bodies, which...     

关于烟蒂环境危害及其管理措施的研究

烟蒂作为随处可见的丢弃物,已成为目前环境中数量最多的固体废物,所致污染日趋严重,但是常被忽视。近年来国外的相关研究报告表明烟蒂具有很强的危害性,但国内各界对烟蒂污染的关注较少。本研究通过系统分析了烟蒂毒性的来源,综述了国外关于烟蒂渗滤液毒性试验的结果,阐明了烟蒂对水生生态系统中代表性物种的危害,并总结了烟蒂的其他潜在环境危害,以呼吁国内各界引起对烟蒂污染和烟蒂危害的重视。最后,提出一些管理方面的建议以破解当前烟蒂的环境管理难题。     

高价离子还原菌还原机理及研究进展

高价离子还原菌普遍存在于自然环境中,它们在环境的原位修复中起着非常重要的作用。本文主要介绍了三种典型的高价离子还原菌：异化Fe（III）还原菌（IRB）、硝酸盐还原菌及硫酸盐还原菌（SRB）,分别以Fe3＋、N03-和SO4^2-为电子受体,以有机物作为电子供体,在将高价离子还原的同时,达到对污染环境的修复作用。文章综述了此类细菌的特性、作用机理、影响因素以及在国内外实际中的应用,分析了异化Fe（III）还原菌、硝酸盐还原菌及硫酸盐还原菌的异同点,并对该类细菌在环境污染治理中的发展趋势进行了评述。     

实验条件对固定化铁粉填料除Cr(Ⅵ)特性的影响

Fe0与Cr(Ⅵ)反应,Fe0极易团聚,利用率极低。通过运用海藻酸钠(SA)固定化铁粉(SAC)来克服Fe0易团聚、利用率低的缺陷。实验结果表明:固定化材料的应用能显著提高零价铁去除Cr(Ⅵ)的能力。FEI电镜扫描及EDX能谱分析结果表明,SA跟2价金属阳离子Ca2+交联形成孔隙结构,不仅为铁粉的附着提供了大量的吸附点位,还可使Cr(Ⅵ)进入到内部与铁粉反应。温度在10²0℃对固定化铁粉填料的除铬性能影响不大;摇床速率越快此填料除铬速率越快,但对Fe0的最终利用率影响不大;pH对填料除铬性能影响很大,酸性条件下去除率最高;此填料在一定程度上会提高含铬废水的pH,但最终都在中性范围波动。     

电化学脱稳技术处理油田含聚污水

采用"电化学除油器—斜板除油器—核桃壳过滤器"模拟装置处理模拟含聚采油污水,考察了有/无清水剂加入条件下含聚污水的处理效果,并对电化学除油机理进行了分析。实验结果表明:各级处理单元的除油率与电化学处理时间成正比,不加入清水剂、电化学处理40 min时,各级处理单元的除油率均超过92%;在电化学除油器前加入清水剂100 mg/L、电化学处理20 min时,各级处理单元的除油率分别为98.8%~99.4%,处理后污水含油量小于30 mg/L,处理效果优于在斜板除油器前加入清水剂;电化学处理与清水剂处理有良好的协同除油效果,可大幅降低清水剂用量。机理分析结果表明,电化学作用主要使吸附于油-水界面的产出聚合物降解、脱稳,实现了对油-水界面膜强度和界面电荷的有效破坏,除油效果优异且处理后的絮体松散、无黏附性。     

The metabolism of neonicotinoid insecticide thiamethoxam by soil enrichment cultures,and the bacterial diversity and plant growth‐promoting properties of the cultured isolates

A soil enrichment culture (SEC) rapidly degraded 96% of 200 mg L^?1 neonicotinoid insecticide thiamethoxam (TMX) in MSM broth within 30 d; therefore, its metabolic pathway of TMX, bacterial diversity and plant growth‐promoting rhizobacteria (PGPR) activities of the cultured isolates were studied. The SEC transformed TMX via the nitro reduction pathway to form nitrso, urea metabolites and via cleavage of the oxadiazine cycle to form a new metabolite, hydroxyl CLO‐tri. In addition, 16S rRNA gene‐denaturing gradient gel electrophoresis analysis revealed that uncultured rhizobacteria are predominant in the SEC broth and that 77.8% of the identified bacteria belonged to uncultured bacteria. A total of 31 cultured bacterial strains including six genera (Achromobacter, Agromyces, Ensifer, Mesorhizobium, Microbacterium and Pseudoxanthomonas) were isolated from the SEC broth. The 12 strains of Ensifer adhaerens have the ability to degrade TMX. All six selected bacteria showed PGPR activities. E. adhaerens TMX‐23 and Agromyces mediolanus TMX‐25 produced indole‐3‐acetic acid, whereas E. adhaerens TMX‐23 and Mesorhizobium alhagi TMX‐36 are N₂‐fixing bacteria. The six‐isolated microbes were tolerant to 200 mg L^?1 TMX, and the growth of E. adhaerens was significantly enhanced by TMX, whereas that of Achromobacter sp. TMX‐5 and Microbacterium sp.TMX‐6 were enhanced slightly. The present study will help to explain the fate of TMX in the environment and its microbial degradation mechanism, as well as to facilitate future investigations of the mechanism through which TMX enhances plant vigor.     

TiO2纳米管的水热合成表征及其光催化性能研究

采用水热化学反应的方法制备了TiO2纳米管,并采用TEM、XRD等分析手段对TiO2纳米管的形貌和晶相进行了表征,对比了管与粉的光催化性能.结果表明,采用该方法制得的TiO2纳米管的管径小、管形均匀,TiO2纳米管的光催化性能明显高于TiO2纳米粉.     

Effects of residual organics in municipal wastewater on hydrogenotrophic denitrifying microbial communities

Hydrogenotrophic denitrification is promising for tertiary nitrogen removal from municipal wastewater. To reveal the influence of residual organics in municipal wastewater on hydrogenotrophic denitrifiers, we adopted high-throughput 16S rRNA gene amplicon sequencing to examine microbial communities in hydrogenotrophic denitrification enrichments. Using effluent from a municipal wastewater treatment plant as water source, COD, nitrate and pH were controlled the same except for a gradient of biodegradable carbon (i.e., primary effluent (PE), secondary effluent (SE), or combined primary and secondary effluent (CE)). Inorganic synthetic water (IW) was used as a control. Hydrogenophaga, a major facultative autotroph, accounted for 17.1%, 5.3%, 32.7% and 12.9% of the sequences in PE, CE, SE and IW, respectively, implicating that Hydrogenophaga grew well with or without organics. Thauera, which contains likely obligate autotrophic denitrifiers, appeared to be the most dominant genera (23.6%) in IW and accounted for 2.5%, 4.6% and 8.9% in PE, CE and SE, respectively. Thermomonas, which is related to heterotrophic denitrification, accounted for 4.2% and 7.9% in PE and CE fed with a higher content of labile organics, respectively. In contrast, Thermomonas was not detected in IW and accounted for only 0.6% in SE. Our results suggest that Thermomonas are more competitive than Thauera in hydrogenotrophic denitrification with biodegradable organics. Moreover, facultative autotrophic denitrifiers, Hydrogenophaga, are accommodating to residual organic in effluent wastewater, thus we propose that hydrogenotrophic denitrification is amenable for tertiary nitrogen removal.     

Development of an on-line measurement system for water-soluble organic matter in PM2.5 and its application in China

Water-soluble organic matter(WSOM) represents a critical fraction of fine particles(PM_(2.5))in the air, but its changing behaviors and formation mechanisms are not well understood yet, partly due to the lack of fast techniques for the ambient measurements. In this study,a novel system for the on-line measurement of water-soluble components in PM_(2.5), the particle-into-liquid sampler(PILS)–Nebulizer–aerosol chemical speciation monitor(ACSM), was developed by combining a PILS, a nebulizer, and an ACSM. High time resolution concentrations of WSOM, sulfate, nitrate, ammonium, and chloride, as well as mass spectra, can be obtained with satisfied quality control results. The system was firstly applied in China for field measurement of WSOM. The mass spectrum of WSOM was found to resemble that of oxygenated organic aerosol, and WSOM agreed well with secondary inorganic ions. All evidence collected in the field campaign demonstrated that WSOM could be a good surrogate of secondary organic aerosol(SOA). The PILS–Nebulizer–ACSM system can thus be a useful tool for intensive study of WSOM and SOA in PM_(2.5).     

酸性甲醛改性对花生壳吸附重金属离子的影响

花生壳的酸性甲醛改性对重金属离子的吸附有较大影响.改性过程使花生壳中一些含有羟基、羧基、芳香环、C-O和C-O-C键的混合物被脱除.改性后花生壳的等电点略有升高,而和羧基有关的表面负电荷量则明显降低.混合物的脱除使Pb2 的吸附量明显降低,Cr3 、Cu2 的吸附量改变不大.改性使羧基减少的同时也暴露了新的Cr3 、Cu2 的吸附位点.改性还有利于增加重金属离子在花生壳内孔中的传质速率,从而使吸附达到平衡的时间略有减少.