Effect of TiO2 nanoparticles and multiwall carbon nanotubes on the freshwater diatom Nitzschia frustulum: evaluation of growth,cellular components and morphology

Great attention should be paid to the possible impacts of various nanoparticles on aquatic organism. Freshwater diatoms are essential components of phytoplankton and play a critical role in bioassessment of nanoparticle exposure in the environment. In this study, cell growth was inhibited by TiO₂-NPs and MWCNTs, the 24?h EC₅₀ values of TiO₂-NPs and MWCNTs to Nitzschia frustulum were 20.75 and 24.64?mg?L^?1, respectively. Significant decreases of Chl a content after TiO₂-NPs exposures were detected and the Chl a content of N. frustulum was obviously increased by MWCNTs treatment at lower concentration. The ROS was detected in N. frustulum after TiO₂-NPs and MWCNTs exposures. The MDA content was significantly induced by TiO₂-NPs at lower concentrations of 24 and 48?h exposure; meanwhile, it increased at all tested concentrations at 24?h MWCNTs exposure. The SOD enzyme was induced by 72 and 96?h TiO₂-NPs exposure, and increased by MWCNTs treatment at 96?h in N. frustulum. Scanning electron microscopy results revealed that N. frustulum had obvious cell deformation after TiO₂-NPs treatment. The result showed that the physiological and biochemical response mechanisms after NPs exposure of diatom were species-specific, and in relation to the exposure concentration and time.     

Rapid control of black and odorous substances from heavily-polluted sediment by oxidation: Efficiency and effects

Oxidants were proposed to rapidly control black and odorous substances in sediments. NaClO and KMnO₄ had excellent efficiency to remove black and odorous substances. NaClO dramatically accelerated the release of organics, NH₄⁺-N, P, and heavy-metals. Moderate oxidation had a limited effect on microbial communities. NaClO of 0.2 mmol/g was viewed to be the optimum option. The control of black and odorous substances in sediments is of crucial importance to improve the urban ecological landscape and to restore water environments accordingly. In this study, chemical oxidation by the oxidants NaClO, H₂O₂, and KMnO₄ was proposed to achieve rapid control of black and odorous substances in heavily-polluted sediments. Results indicate that NaClO and KMnO₄ are effective at removing Fe(II) and acid volatile sulfides. The removal efficiencies of Fe(II) and AVS were determined to be 45.2%, 94.1%, and 93.7%, 89.5% after 24-h exposure to NaClO and KMnO₄ at 0.2 mmol/g, respectively. Additionally, rapid oxidation might accelerate the release of pollutants from sediment. The release of organic matters and phosphorus with the maximum ratios of 22.1% and 51.2% was observed upon NaClO oxidation at 0.4 mmol/g. Moreover, the introduction of oxidants contributed to changes in the microbial community composition in sediment. After oxidation by NaClO and KMnO₄ at 0.4 mmol/g, the Shannon index decreased from 6.72 to 5.19 and 4.95, whereas the OTU numbers decreased from 2904 to 1677 and 1553, respectively. Comparatively, H₂O₂ showed a lower effect on the removal of black and odorous substances, pollutant release, and changes in sediment microorganisms. This study illustrates the effects of oxidant addition on the characteristics of heavily polluted sediments and shows that chemical oxidants may be an option to achieve rapid control of black and odorous substances prior to remediation of water environments.     

Properties of mortars made by uncalcined FGD gypsum-fly ash-ground granulated blast furnace slag composite binder

A series of novel mortars were developed from composite binder of uncalcined FGD gypsum, fly ash (FA) and ground granulated blast furnace slag (GGBFS) for the good utilization of flue gas desulphurization (FGD) gypsum. At a fixed ratio (20%) of GGBFS to the composite binder, keeping consistency of the mortar between 9.5 and 10.0 cm, the properties of the composite mortar were studied. The results show that higher water/binder (W/B) is required to keep the consistency when increasing the percentage of FGD gypsum. No obvious influences of the W/B and content of FGD gypsum on the bleeding of paste were observed which keeps lower than 2% under all experimental conditions tried. The highest compressive and flexural strengths (ratio is 20% FGD gypsum, 20% GGBFS and 60% FA) are 22.6 and 4.3 MPa at 28 days, respectively. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that massive ettringite crystals and C-S-H gels exist in the hydration products. At 90 days the mortars with FGD gypsum is dramatically smaller drying shrinkage (563-938 micro strain) than that without FGD gypsum (about 2250 micro strain). The release of the SO(4)(2-) from the mortar was analyzed, indicating that the dissolution of sulfate increases with FGD gypsum. The concentration of SO(4)(2-) releasing from the mortar with 10% FGD gypsum is almost equal to that obtained from the mortar without FGD gypsum. The release of SO(4)(2-) from the mortar with 20% FGD gypsum is 9200 mg·m(-2), which is lower than that from the mortar with 95% cement clinker and 5% FGD gypsum.     

Fenton试剂强化微电解工艺预处理难降解含氰农药废水

采用Fenton试剂强化微电解反应预处理难降解含氰农药废水.实验结果表明,在总反应时间为3.0 h、反应开始时加入1 mL/L H2O2、反应1.5 h后再加入3mL/L H2O2的条件下,出水COD为372.0 mg/L,COD去除率可达80.2％,出水p(CNˉ)为2.2 mg/L,色度为20倍,BOD5/COD为0.35,可实现处理效果与经济成本的最优化.采用紫外-可见光谱分析处理后废水,发现Fenton试剂强化微电解反应可破坏部分微电解作用难以降解的有机物,但对苯环的降解能力均有限.     

阴极电势对微生物电合成系统还原CO2合成有机物性能的影响

采用微生物电合成系统（MES）还原CO₂合成有机物,从微生物菌群、有机物积累量、库伦效率、电化学分析等多个角度研究了阴极电势对MES还原CO₂合成有机物性能的影响。实验结果表明：阴极电势为-0.70 V时,甲酸和乙酸的积累量均最大（分别为1.554 mmol/L和2.754 mmol/L）,系统的总库伦效率最大（为81.42%）;在MES中,醋杆菌（Acetobacterium sp.）、假丝酵母菌（Candida sp. S）、地杆菌（Geobacter sp.）为优势菌种。     

废旧聚乙烯的再生处理技术

从废旧聚乙烯的直接再生、改性再生和裂解再生三个方面,讨论了国内外处理和再生利用的情况,并对其再生技术与应用做了比较.我国处理和回收利用废旧聚乙烯时,要加强生物降解塑料等环境无负荷材料的研究与开发;加强固体废弃物的管理与循环利用的立法;实现经济与环境的和谐发展.     

泥石流灾情综合评估模式

泥石流灾情综合评估模式是在灾情绝对评估的基础上建立的。首先，建立了泥石流灾情评估的步骤框图；然后依据已有的泥石流灾情评估指标体系对各项指标进行量化分析处理，将得了各灾情评估指标公值分布及其量纲换算法，确定了反映直接损失的灾情绝对评估指标和相对评估指标（直接经济损失占灾区国民收入的比例），并对绝对和相对评估结果的等级进行了划分；最后，建立了绝对评估和相对评估结果对比的灾情综合评估模式。经过实例应用验证，评估结果能较好地反映灾情。     

Stochastic analysis of radioactive waste package performance using first-order reliability method

In order to license an underground radioactive waste repository, it is important to demonstrate regulatory compliance with authoritative regulations. Also it is evidence from NRC's criteria for waste package performance that a stochastic analysis is necessary to provide that these criteria can be met with confidence. The first-order reliability method is an attractive tool to the stochastic analysis and particularly useful when statistical information is incomplete, as is common for problems occurring in the subsurface environment. The method is based on using the first-order Taylor series expansion at a specific linearization point to calculate a measure of reliability. Results from a first-order reliability analysis include an estimate of the probability of exceeding a specified performance criteria and measures of the sensitivity of the stochastic solution to the changes in input random variables and their statistical moments. The method of stochastic analysis is illustrated by analyzing the canister corrosion in a radioactive waste package.     

国内旅游者人口学特征与行为分析——以延边朝鲜族自治州为例

边境型旅游地因其独特的边境自然风貌、浓厚的异族风情在我国丰富的旅游资源中占有重要地位。通过实地考察，根据游客调查问卷数据和二手资料，与海滨型旅游地普陀山、古村落型旅游地西递和宏村、山岳型旅游地泰山进行了对比分析，揭示了延边朝鲜族自治州国内旅游者的人口学特征、旅游行为、旅游效果等，并就促进其旅游业的进一步发展提出了建议。     

废电路板非金属材料再生利用技术现状分析

废电路板金属成分分离回收过程中产生了占其质量近50%～80%的非金属材料废物,其已成为电子废物处理的难题。文章首先对废电路板非金属材料的产生特性、处理和处置、资源化利用技术和方法现状进行了对比分析。在此基础上,结合对非金属材料的来源特征、成分组成和界面微观特性等各方面分析研究,提出了非金属材料制备复合材料再生利用的技术工艺方案。