碳源对含盐废水短程硝化反硝化的影响

分别采用醋酸钠、甘油、乙醇和葡萄糖作为外加碳源,研究不同碳源对含盐废水短程硝化反硝化的影响.结果表明:(1)利用醋酸钠作为碳源,逐步增加NaCl盐度可以实现短程硝化反硝化,TN平均去除率高于95％.当NaCl盐度为14.2 g/L时,采用醋酸钠、甘油、乙醇和葡萄糖作为碳源时,NO2- -N的累积率分别为98.7％、86...     

Hydrodechlorination of dichlorobenzenes and their derivatives over Ni-Mo/C catalyst: kinetic analysis and effect of molecular structure of reactant

The kinetics of the catalytic hydrodechlorination (HDC) process of selected dichlorobenzenes (DCBs), dichlorotoluenes (DCTs) and dichlorodiphenyls (DCDs) was studied in the presence of a sulphided carbon-supported Ni-Mo catalyst. The HDC runs were performed in a magnetic stirred batch reactor in the range of 210-230 °C under the hydrogen pressure of 3 MPa. The kinetic constants were evaluated and the reaction network was proposed assuming the pseudo-first order kinetics of dechlorination process. The HDC of aromatic dichloroderivatives proceeded via a network of sequential-parallel reactions. At 210 °C DCBs, DCTs and DCDs followed mainly the pathway of direct transformation to respective aromatic hydrocarbon. At 230 °C, the contribution of sequential dechlorination to monochloroderivative became more predominant.     

Differential toxicity of silver and titanium dioxide nanoparticles on Drosophila melanogaster development, reproductive effort, and viability: size, coatings and antioxidants matter

Silver and titanium dioxide nanoparticles are known to induce oxidative stress in vitro and in vivo. Here we test if they impact development, mating success, and survivorship in Drosophila melanogaster, and if so, if these effects are reversible by antioxidants. Ingestion of nanotitanium dioxide during the larval stage of the life cycle showed no effects on development or survivorship, up to doses of 200 μg mL⁻¹. Conversely, ingestion of nanosilver had major dose, size, and coating-dependent effects on each of these aspects of life history. Each of these effects was partially or fully reversible by vitamin C. Larvae growing on nanosilver supplemented with vitamin C showed a greater than twofold increase in survivorship compared to flies reared on nanosilver alone, and a threefold increase in mating success. Vitamin C also rescued cuticular and pigmentation defects in nanosilver fed flies. Biochemical assays of superoxide dismutase and glutathione show these markers respond to nanotitanium dioxide and nanosilver induced oxidative stress, and this response is reduced by vitamin C. These results indicate that life history effects of nanosilver ingestion result from oxidative stress, and suggest antioxidants as a potential remediation for nanosilver toxicity. Conversely, the lack of nanotitanium dioxide life history toxicity shows that oxidative stress does not necessarily result in whole organism effects, and argues that nanoparticle toxicity needs to be examined at different levels of biological organization.     

Nickel sulfate induces numerous defects in Caenorhabditis elegans that can also be transferred to progeny

Whether the multiple biological toxicities from nickel exposure could be transferred to progeny has not been clarified. In this report, we explored the Caenorhabditis elegans to analyze the multiple toxicities of nickel and their possibly transferable properties. The nickel toxicity caused multiple biological defects in a concentration-dependent manner. Moreover, most of these toxicities could be transferred and could be only partially rescued in progeny. Some specific phenotypes in progeny were also found to exhibit no obvious rescue phenotypes or to show even more severe defects than their parents. The defects caused by nickel exposure could be classified into four groups according to their transferring properties. That is, the defects caused by nickel exposure could be largely, or partially, or unable to be rescued, or became even more severe in progeny animals. Therefore, most of the nickel exposure-caused defects can be transferred from parents to their progeny to different degrees in C. elegans.     

The ratio of clay content to total organic carbon content is a useful parameter to predict adsorption of the herbicide butachlor in soils

Thirteen soils collected from 11 provinces in eastern China were used to investigate the butachlor adsorption. The results indicated that the total organic carbon (TOC) content, clay content, amorphous Fe2O3 content, silt content, CEC, and pH had a combined effect on the butachlor sorption on soil. Combination of the data obtained from the 13 soils in the present study with other 23 soil samples reported by other researchers in the literature showed that Koc would be a poor predictive parameter for butachlor adsorption on soils with TOC content higher than 4.0% and lower than 0.2%. The soils with the ratio of clay content to TOC content (RCO) values less than 60 adsorbed butachlor mainly by the partition into soil organic matter matrix. The soils with RCO values higher than 60 apparently adsorbed butachlor by the combination of the partition into soil organic matter matrix and adsorption on clay surface.     

Chromosomal genes conferring tolerance to heavy metal (Ag) toxicity

Bacterial strains were isolated from sediment samples from the Thames River. Successive transfer growth of the various strains on nutrient agar containing increasing concentrations of AgNO₃ revealed that three of the bacterial isolates were found to be capable of tolerating high concentrations of AgNO₃ ranging from 20 to 80 mM on a solid medium and up to 10 mM AgNO₃ in liquid medium. Molecular characterization and identification based on 16S rDNA gene sequencing of three strains of bacteria that are tolerant to silver nitrate showed that the major tolerant strains include the superbug, Shewanella oneidensis, Pseudomonas sp. and Bacillus sp. Protein extraction and two-dimensional (2D) sodium dodecyl sulfate SDS-polyacrylamide gel electrophoresis (PAGE) of the protein extracts in bacteria exposed to very high concentrations of AgNO₃ revealed a general reduction in the number of expressed proteins, although two protein spots were conspicuously over expressed in the exposed bacteria compared to control. The N-terminal amino acid sequence analysis of the protein spots identified the major up-regulated proteins as the outer membrane protein To1C (45.2 kDa) and the structural protein of the flagellar filament, flagellin (28.34 kDa), encoded for by the to1C and fliC genes, respectively. The roles of these genes in a number of multi-drug resistant pathogen and potentials for biotechnological applications in toxic metal control for treatment of contaminated ecosystems and biomining were discussed.     

白洋淀沼泽区与开阔水域区颗粒物组分特征与沉降通量研究

选取白洋淀的沼泽区(烧车淀)与开阔水域区(采蒲台)为研究区域,分析了水体中新生沉降颗粒物组分组成、沉降通量及其来源.结果表明,两种典型水域中水体颗粒物组分差异显著,其中,烧车淀水域颗粒物成分以有机质(OM)为主,质量占比达到49.59%～74.14%;而采蒲台水域颗粒物以无机组分为主,占比为54.52%～79.27%.烧车淀沉降颗粒物中总碳(TC)、总氮(TN)含量分别为(221.16±39.73)g·kg^-1和(21.10±1.67)g·kg^-1;采蒲台沉降颗粒物中TC和TN的含量分别为(172.28±91.22)g·kg^-1和(15.72±8.12)g·kg^-1.由固相¹³C CP/MAS NMR光谱结果分析出白洋淀沉降颗粒物中碳组分以烷基碳、烷氧基碳为主,其中,烧车淀淀面水域颗粒物中以易分解碳烷氧基碳为主(65.65%),采蒲台淀面水域颗粒物中以较稳定烷基碳为主(50.76%).开阔水域区颗粒物沉降通量高于沼泽化区,均值分别为10.63 g·m^-2·...     

甲磺隆在土壤腐殖物质中结合残留的动态变化

土壤中14 C 甲磺隆的可提取态残留物随时间延长不断降低 ,而其结合态残留率第 2 8天达最高 .14 C 甲磺隆结合态残留物在土壤腐殖物质中的分布是 :富啡酸 胡敏素 >胡敏酸 .在处理最初 2 8天 ,富啡酸中14 C 甲磺隆结合态残留物不断增大 ,随后减少 ;胡敏素中的结合态残留量在 2 8— 2 2 4天变化不大 .14 C残留物在不同土壤之间的结合及其分布都是有差异的 ,与土壤pH值、粘粒矿物类型等都有密切关系     

Recent advances in special morphologic photocatalysts for NOx removal

● Systematic information of recent progress in photocatalytic NO _x removal is provided. ● The photocatalysts with special morphologies are reviewed and discussed. ● The morphology and photocatalytic NO _x removal performance is related. The significant increase of NO_x concentration causes severe damages to environment and human health. Light-driven photocatalytic technique affords an ideal solution for the removal of NO_x at ambient conditions. To enhance the performance of NO_x removal, 1D, 2D and 3D photocatalysts have been constructed as the light absorption and the separation of charge carriers can be manipulated through controlling the morphology of the photocatalyst. Related works mainly focused on the construction and modification of special morphologic photocatalyst, including element doping, heterostructure constructing, crystal facet exposing, defect sites introducing and so on. Moreover, the excellent performance of the photocatalytic NO_x removal creates great awareness of the application, which has promising practical applications in NO_x removal by paint (removing NO_x indoor and outdoor) and pavement (degrading vehicle exhausts). For these considerations, recent advances in special morphologic photocatalysts for NO_x removal was summarized and commented in this review. The purpose is to provide insights into understanding the relationship between morphology and photocatalytic performance, meanwhile, to promote the application of photocatalytic technology in NO_x degradation.     

气水比对A/O-BF处理低碳氮比农村生活污水脱氮的影响

为揭示好氧段气水比对缺氧/好氧生物滤池(Anoxic/Oxic Biofilter,A/O-BF)脱氮的影响机理,采用A/O-BF处理低碳氮比农村生活污水,结合实时荧光定量聚合酶链式反应技术,对比研究了好氧段气水比为4∶1、2∶1和1∶1时A/O-BF的脱氮效能和微生物群落变化特征.结果表明:当气水比为4∶1时,A/O...