Treatment of tannery wastewater by electrocoagulation

Treatment of tannery wastewater by electrocoagulation with low cell current(≤1A)and soluble electrodes(mild steel electrodes and aluminum electrodes)was studied.Compared with aluminum electrodes,mild steel electrodes were more effective for the removal of sulfide,with a removal efficiency of over 90%.But during the treatment process,black color precipitate typical to iron(Ⅱ)sulfides was produced.While aluminum electrodes were effective to eliminate the colority of the effluent,the removal efficiency of sulfide was lower than 12%.The mechanisms of the removal of chemical oxygen demand,ammonia,total organic carbon,sulfide and colority with the two soluble electrodes(mild steel and aluminum electrodes)were discussed in detail.In order to exert the predominance of diffenent types of electrodes,the tannery wastewater was treated using mild steel electrodes first followed by the filter and finally by the aluminum electrodes,the elimination rates of chemical oxygen demand,ammonia,total organic carbon,sulfide and colority were 68.0%,43.1%,55.1%,96.7% and 84.3%,respectively,with the initial concentrations 2413.1 mg/L,223.4 mg/L,1000.4 mg/L,112.3 mg/L and 256 dilution times,respectively.The absorbance spectra and energy consumption during electrocoagulation process were also discussed.     

全氟辛烷磺酸(PFOS)对人骨髓间充质干细胞PPARs亚型及分化潜能的影响

过氧化物酶体增殖物激活受体(peroxisome proliferators-activated receptors,PPARs)是全氟辛烷磺酸(perflurooctane sulfon-ate,PFOS)的首要分子靶标,但PPARs各亚型在PFOS毒性效应中可能产生不同调控作用,相关机理并不清楚.本研究采用人骨髓间...     

具有超压/负压防护功能的急救车防生物污染的安全性试验研究

采用粘质沙雷菌气溶胶,对具有超压/负压防护功能的急救车防生物污染的安全性进行试验考核。分别测试气溶胶发生后30s,1min,5min,10min时,车厢在超压防护和负压防护下的过滤效率,其结果表明:急救车在超压防护状态下开启空调时的平均过滤效率能达到99.99%,不开空调时的平均过滤效率能达到99.95%;在负压防护状态下开启空调时的平均过滤效率能达到99.93%,不开空调时的平均过滤效率能达到99.95%。证明急救车能够通过生物污染区域安全运送、急救伤病员,也能够运送、急救生物污染伤病员或烈性传染病员确保沿途环境不受污染,该研究成果为应对生物恐怖袭击和突发公共卫生事件(烈性传染病)提供了一种安全可靠的机动医疗救治平台。     

我国危险化学品企业搬迁方案研究

概要地对我国现有危险化学品企业安全防护距离不足的现状进行分析,提出危险化学品企业搬迁工作实施的基本原则,探讨危险化学品企业搬迁范围的确定、厂址的解决、资金的分配、政策的制定和长效机制的建立等问题。建议搬迁企业在政府的统一规划下,坚持以人为本,坚持安全生产和可持续发展的原则,在搬迁中提高技术含量和社会形象,增强市场竞争力。针对我国危险化学品企业的特点提出了一套搬迁方案和步骤。论文的研究成果将为各地政府指导当地危险化学品企业进行科学规划,对待搬迁的危险化学品企业实现安全有效搬迁及健康发展提供了有益参考。     

巧用Premiere Pro 2.0 制作艺术倒计时片头

Premiere Pro 2.0 是用于编辑影视作品的专业软件,可以编辑和制作电影、DV、栏目包装、字幕、网络视频、电子相册等.本文介绍了其自带的制作倒计时片头效果模板的使用方法,提出了利用Premiere Pro 2.0视频转场特效结合专业制图软件制作艺术倒计时效果的具体方法.     

Land Use,Geology, Enrichment,and Stream Biota in the Eastern Ridge and Valley Ecoregion: Implications for Nutrient Criteria Development1

Abstract: The eastern panhandle region of West Virginia is entirely within the Appalachian Ridge and Valley ecoregion. It is underlain by limestone in the eastern part and by shale and sandstone in the western part. Agricultural and urban development has affected the condition of the streams of this region. We examined samples from 165 stations in the Ridge and Valley, collected from 1998 to 2004. Land use, geological characteristics, physical and chemical parameters, and algal and macroinvertebrate assemblages were used to identify potential stressors that affect streams in the region. Our analyses indicated that both human land uses and ecoregional differences led to elevated nutrient concentrations in streams of the study areas. Multiple regression analyses indicated that both agricultural and urban land use in the watershed were associated with high nutrient concentrations (NO₂₊₃, total nitrogen, and total phosphorus) in streams. These elevated nutrient concentrations have led to increased algal biomass, increased trophic state, and degradation of macroinvertebrate community in the streams. Values of the West Virginia Stream Condition Index, as well as several other benthic macroinvertebrate metrics, decreased with increased nutrient concentrations and conductivity, especially in the limestone region. When regional differences were partitioned out in the analysis, nutrient concentrations became the strongest stressor in the limestone region while conductivity exhibited less of an effect on macroinvertebrate metrics. Meanwhile, periphyton diagnostic metrics also responded to increased nutrient concentrations, suggesting nutrients could be a cause of biological degradation in the Eastern Ridge and Valley region. Multiple approaches and multiple lines of evidence (reference approach and stressor‐response approach) were applied to develop nutrient benchmarks for different geological regions in the study watershed.     

Reactive transport modeling of column experiments on the evolution of saline-alkaline waste solutions

Leakage of saline-alkaline tank waste solutions often creates a serious environmental contamination problem. To better understand the mechanisms controlling the fate of such waste solutions in the Hanford vadose zone, we simulated reactive transport in columns designed to represent local site conditions. The Pitzer ion interaction module was used, with principal geochemical processes considered in the simulation including quartz dissolution, precipitation of brucite, calcite, and portlandite, multi-component cation exchange, and aqueous complexation reactions. Good matches were observed between the simulated and measured column data at ambient temperature ( approximately 21 degrees C). Relatively good agreement was also obtained at high temperature ( approximately 70 degrees C). The decrease of pH at the plume front is examined through formation of secondary mineral phases and/or quartz dissolution. Substantial formation of secondary mineral phases resulting from multi-component cation exchange suggests that these phases are responsible for a decrease in pH within the plume front. In addition, a sensitivity analysis was conducted with respect to cation exchange capacity, selectivity coefficient, mineral assemblage, temperature, and ionic strength. This study could serve as a useful guide to subsequent experimental work, to thermodynamic models developed for the concentrated solutions at high ionic strength and to other types of waste plume studies.     

微分脉冲阴极溶出伏安法测定环境水样中的痕量硒

采用微分脉冲阴极溶出法测定环境水样中的痕量硒,以银电极为工作电极,在酸性介质0.06mol.l^-1HCl-0.07mol.l^-1HNO3溶液中于－0.35V(vs SCE)处富集20min,使Se(IV)电沉积为硒化银,然后,以40mV.s^-1的扫速,在碱性介质2．0mol.l^-1NaOH溶液中阴极溶出至－1.2V(vsSCE),硒化银被还原为银的溶出峰电位约为－0.85V(vs SCE),硒的分析校正曲直到40ng.ml^-1仍然成线性,检测下限为11.5pg.ml^-1,相关系为0.9982,灵敏度为10.93uA/ng.ml^-1,20ng.ml^-1的RSD（n=5)为1．26％,检出限（3σ为3.46pg.ml^-1,环境水样中常见离子的存在不干扰痕量硒的测定。     

乙草胺和丁草胺的水解及其动力学

本文研究了乙草胺和丁草肢在恒温２５℃,ｐＨ值为４,７,１０蒸馏水和河水中的水解动力学．酰胺类除草剂的水解反应属于一级反应．结果显示乙草胺和丁草胺在蒸馏水和河水中的水解速度差不多,在ｐＨ ４水溶液中的水解速度较在ｐＨ７和１０的速度快,Ｈ＋有催化水解的作用．乙草胺在ｐＨ４,７,１０的速率常数分别为５×ｌ０－４ｄ－１,３×１０－４ｄ－１,３×１０－４ｄ－１．半衰期分别为１３８６ｄ,２３ｌ０ｄ,２３１０ｄ．丁草胺在ｐＨ４,７,１０的速率常数分别为 ｌ．１× １０－３ｄ－１,６ × １０－４ｄ－１,６ × １０－４ｄ－１．半衰期分别为 ６３０ｄ,１１５５ｄ,１１５５ｄ．