浅析土壤环境中的镉的影响

由于工业的污染使土壤中镉的含量增加,从而直接导致对食物链的影响,文章以镉为例,进行研究.而研究高等植物是生态系统的重要组成部分,一个平衡、稳定的生态系统生产健康、优良的高等植物.因此,利用高等植物的生长状况诊断土壤污染,是土壤毒理诊断的重要方法之一.     

恐怖事件中恐怖分子常用化学武器的分类

为了作好"反恐怖"工作,必须了解和掌握恐怖分子采用的武器性能,文章简要介绍了恐怖分子所使用的四种化学武器的性能、毒性、毒物的初步识别等方法.     

北方中小城市园林绿化中存在的问题及建议

进入新世纪,国家对生态环境越来越重视,城镇建设必须与生态环境相协调,走可持续发展的道路.城市绿化在改善生态环境方面具有巨大作用.在此就城市园林绿化过程中存在的问题及如何搞好城市园林绿化作了充分的阐述,希望对园林绿化工作的开展起到积极推动作用.     

典型飞机内腔结构腐蚀原因分析及防腐改进

以典型飞机平尾大轴为例,分析了内腔结构发生腐蚀的主要原因.围绕内腔结构防腐改进技术措施开展深入研究,研制成功了适用于细长内腔无气喷涂设备.应用SLF重防腐涂层和IMR纳米复合涂层替代现有内腔结构防护涂层,提高了防腐涂层抗环境腐蚀性能.采用DL-609厌氧胶对平尾大轴进行密封处理,有效地阻隔了腐蚀介质进入内腔.按照所建立的方法对典型飞机平尾大轴实施了腐蚀修理与防护处理.检查结果表明,内腔表面防腐状况有了明显改善.     

铅盐生产企业对周边生态环境的影响

通过连续多年的系统监测和分析,研究了小型铅盐生产企业对周边大气、水、土壤、河流底质和农作物等生态环境的影响.研究发现,生产车间和距其100 m以外的居民区大气中铅尘分别超标548倍和4倍;500 m以外的农田土壤中铅超标1.26倍;雨水排放口附近河道水质中铅超标1.08倍;雨水排放口附近及下游800 m处的河道底质中铅分别超标1.99倍和1.33倍;500 m以外种植的小麦籽粒中铅超标16.5倍.环境污染的程度与距污染源的空间距离呈负相关.在此,还对小型重金属生产企业的环境监测和防止污染的转移提出了建议.     

诺砂试制经济型地面砖的研究

论述了对诺砂采用压制成型法试制低成本地面砖的工艺流程、试验过程及其结果分析,并对其反应机理进行了简单的探讨,为诺砂的综合利用提供了一定的参考.     

资讯快递

要闻6月21日,环境基准与风险评估国家重点实验室揭牌仪式在中国环境科学研究院举行,环境保护部部长周生贤、科技部副部长陈小娅出席仪式并共同为重点实验室揭牌。     

新知

1废水发电机根据Broadbent的统计,1栋7层高的楼房安装这台废水发电机后可以每年节省1000美元的电费。在不久的将来就会进入消费市场了。2蜂巢轮胎     

天津市领导出席国务院节能减排天津分会场会议

9 月27 日,国务院召开节能减排工作电视电话会议.天津市委常委、常务副市长杨栋梁,副市长王治平出席天津分会场会议并讲话. 杨栋梁、王治平指出,温家宝总理在此次电视电话会议上所作的重要讲话,站在全局和战略的高度,对下一步做好节能减排工作提出明确要求,进行了系统部署.全市各区县、各部门、各单位要深入贯彻落实,把节能减排作为调整产业结构、转变发展方式的重要抓手,认真分析当前形势,进一步加大工作力度,确保圆满完成全年节能减排目标任务,保证"十二五"节能减排工作开好局、起好步.     

绿色风尚标:生产者责任延伸

"生产者延伸责任"一词是最早由Thomas Lindhqvist在1988年提交给瑞典环境部的报告中最早提出的,报告认为生产者的责任应该延伸到整个产品的生命周期.欧盟把生产者延伸责任定义为生产者必须承担产品使用完毕后的回收、再生和处理的责任,其策略是将产品废弃阶段的责任完全归于生产者,目前大多数国家采用欧盟的定义.     

电动力和铁PRB技术联合修复铬(Ⅵ)污染土壤

考察了电动力学方法对模拟铬(Ⅵ)污染土壤以及天津市原同生化工厂遗留下的铬渣山周边土壤的修复效果,并将该技术与铁可渗透反应格栅(permeable reactive barrier,PRB)技术联用,找出了较好的联用方式,与单一电动修复进行了对比.研究表明,电动力学技术能有效地修复被铬(Ⅵ)污染的土壤,模拟污染土壤铬(Ⅵ)的去除率达98%～100%,总铬去除率在阳极室附近为80%左右,而阴极室附近则为90%以上,恢复到土壤背景值;铬(Ⅵ)去除的同时伴随着铬(Ⅵ)向铬(Ⅲ)的转化,修复结束时土壤中残留的铬90%以上为铬(Ⅲ);污染极其严重的铬渣山下土,由于含约28%的铬(Ⅲ),修复结束时铬(Ⅵ)的去除率达98%以上,而总铬去除率仅为75%～77%;阳极室附近土壤pH降低而阴极室附近土壤pH升高,处于两极中间位置的pH变化不大.电动力学与铁PRB原位联用方式能充分地利用这2种技术的优点,修复后,土壤任意位置的总铬去除率接近90%,阳极室附近尤为好于单一电动修复,对土壤pH的影响也较小.     

高浓度含铬废水的综合利用

探讨了高浓度含铬褪铜废液的处理方法 ,根据该废液铬含量高 ,具有回收利用价值的特点 ,提出了一条综合利用含铬废液的工艺路线。将含铬废液在合适的条件下把Cr(Ⅲ )氧化为Cr(Ⅵ ) ,加合适的沉淀剂除杂质后 ,加入铅盐溶液 ,生成铬黄     

Response of soil catalase activity to chromium contamination

The impact of chromium(III) and (VI) forms on soil catalase activity was presented. The Orthic Podzol, Haplic Phaeozem and Mollic Gleysol from di erent depths were used in the experiment. The soil samples were amended with solution of Cr(III) using CrCl3, and with Cr(VI) using K2Cr2O7 in the concentration range from 0 to 20 mg/kg, whereas the samples without the addition of chromium served as control. Catalase activity was assayed by one of the commonly used spectrophotometric methods. As it was demonstrated in the experiment, both Cr(III) and Cr(VI) have an ability to reduce soil catalase activity. A chromium dosage of 20 mg/kg caused the inhibition of catalase activity and the corresponding contamination levels ranged from 75% to 92% for Cr(III) and 68% to 76% for Cr(VI), with relation to the control. Catalase activity reached maximum in the soil material from surface layers (0–25 cm), typically characterized by the highest content of organic matter creating favorable conditions for microorganisms.     

风化铬渣与新鲜铬渣中六价铬溶出特性的研究

采用直接淋浸法对风化铬渣及新鲜铬渣进行了六谷铬溶出的条件试验，60min的浸泡时间，80目以下的粒度对渣水比250g/200mL的新渣中Cr(VI)浸出率达69．4％，渣水比250g/200mL,500g/400mL,750g/600mL的风化渣中Cr(VI)的总溶出率分别为70．2％，86．3％，94．0％，其中第一次淋滤溶出率分别达48．1％，70．0％，81．6％，低PH值的淋浸水有利于Cr(VI)的浸出，在PH值为3时溶出率达高峰，Cr（VI）浸出质量比自然条件（近中性）高出14．1％－16．3％，增大管径和降低装置的滤面负荷可提高浸出效果，在直径80mm管径，500g铬渣装填料，滤面负荷9．95g/cm^2时，Cr（VI）溶出率达98．7％，真空抽滤可提高Cr（VI）浸出速率，但降低了滤液中Cr（VI）的浓度和溶出质量，上述试验结果表明了直接淋浸法回收铬渣中六价铬的可行性，并可作为工业化装置的设计参数。     

Elimination of a pollution associated with chromic acid during the electro-deposition of Cr(III) using appropriate anodic and membrane materials in a double film bath

A method using trivalent chromium has been used to replace hexavalent chromium for the electro-deposition of chromium. Using a tri-chamber bath system various anodic materials and membranes were evaluated to minimize the production of environmentally and health damaging chromic acid. By measuring the absorbance of Cr(VI) at 640 nm, the results indicate that the use of a titanium plated ruthenium (Ti-Ru) anode produces the least amount of chromic acid byproduct compared to lead-gold alloy and graphite anodes. The concentration of Cr(VI) in the immediate vicinity of the Ti-Ru anode decreased from 0.389 mg/L to 0 during a 40-min deposition period. The use of a Nafion^TM quaternary cation exchange membrane portioning the buffer and anode selectively prevented Cr(III) from entering the anode compartment whilst allowing the migration of H⁺ to maintain overall voltaic continuity. It has been demonstrated that the use of a Ti-Ru anode with a Nafion^TM membrane can eliminate the production of chromic acid associated with the electro-deposition of chromium plate thereby preventing its health damaging exposure to plant operators and preventing discharge of Cr(VI) into the environment. Addition of a surfactant improved current efficiency by 34.7%.     

Experimental study on Cr(Ⅵ) reduction by Pseudomonas aeruginosa

Investigation on Cr( Ⅵ ) reduction was conducted using Pseudomonas aeruginosa. The study demonstrated that the Cr(Ⅵ) canbe effectively reduced to Cr( Ⅲ ) by Pseudomonas aeruginosa. The effects of the factors affecting Cr( Ⅵ ) reduction rate including carbon source type, pH, initial Cr(Ⅵ) concentration and amount of calls inoculum were thoroughly studied. Malate was found to yield maximum biotransformation, followed by succinate and glucose, with the reduction rate of 60.86%, 43. 76% and 28.86% respectively. The optimum pH for Cr( Ⅵ ) reduction was ?.0, with reduction efficiency of 61.71 % being achieved. With the increase of initial Cr(Ⅵ) concentration,the rate of Cr(Ⅵ) reduction decreased. The reduction was inhibited strongly when the initial Cr(Ⅵ) concentration increased to 157 mg/L. As the amount of cells inoculum increased, the rate of Cr( Ⅵ ) reduction also increased. The mechanism of Cr( Ⅵ ) reduction and final products were also analysed. The results suggested that the soluble enzymes appear to be responsible for Cr (Ⅵ) reduction by Pseudomonas aeruginosa, and the reduced Cr( Ⅲ ) was not precipitated in the form of Cr(OH)3.     

Arsenic and chromate removal from water by iron chips-Effects of anions

The purpose of this study is to estimate the removal efficiency of As and Cr (VI) by one kind of industrial waste — iron chips, as well as to estimate the effects of typical inorganic anions (sulfate, phosphate, and nitrate), and typical organic anions (citrate, oxalate, and humate) on As or Cr (VI) removal. The results showed that 98% of As (V) and 92% of As (III) could be removed from aqueous phase by the iron chips within 60 min. Compared with As species, Cr (VI) was removed much more rapidly and efficiently with 97% of Cr (VI) being removed within 25 min. The removal efficiency for arsenic was in the order: As (III) (sulfate), As (III) (nitrate) or As (III), As (III) (humate), As (III) (oxalate), As (III) (citrate), As (III) (phosphate), and for chromate was in the order: Cr (VI) (sulfate), Cr (VI) (phosphate) or Cr (VI) (nitrate) or Cr (VI) (oxalate), Cr (VI), Cr (VI) (citrate), Cr (VI) (humate). In all the treatments, pH level increased with time except for As (III), the removal of which was either without anions or in the presence of humate or nitrate.     

Study on activated carbon in chromium-containingwastewater treatment by XPS

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硫代硫酸钠、磷酸钠联合处理铬渣中的六价铬

以硫代硫酸钠为还原剂,将铬渣中的六价铬(Cr(VI))解毒转化为三价铬(Cr(III)),并加入磷酸盐作为稳定剂稳定解毒后的铬渣,考察不同反应时间和药剂用量对铬渣中Cr(VI)去除效果的影响.结果表明:硫代硫酸钠可以有效去除铬渣中的Cr(VI),当其与Cr(VI)的摩尔比为理论摩尔比的12倍、处理时间15d时铬渣中Cr(VI)的去除率达到最高(70%),继续增加还原剂用量或延长反应时间均不能有效提高Cr(VI)的去除率.随后加入磷酸钠作为稳定剂,当其物质的量为生成Cr(III)的4倍时,硫代硫酸钠与磷酸钠分步加入(两步法)比同时加入(一步法)处理铬渣的效果较好,处理效果最好时总铬浸出浓度为6.1mg/L,低于危险废物浸出鉴别的总铬标准(15mg/L),而且形成稳定的铬的化合物(CrPO4·6H2O).铬渣pH值变化、五态变化、XRD及XPS分析等结果表明,两步法的处理效果好于一步法.     

可渗透反应复合电极法对铬(Ⅵ)污染土壤的电动修复

将Fe0、沸石等活性材料附着在电极上构成可渗透反应复合电极,以Cr(Ⅵ)污染土壤为处理对象,对电动修复过程中可渗透反应复合电极法对土壤pH的控制、Cr的去除效果以及形态变化进行了研究.结果表明,添加可渗透反应材料的复合电极法比单一电极法无论在土壤pH控制还是Cr的去除方面都有明显的改善和提高,其中以在阳极同时添加Fe0和沸石效果最为显著.在施加2 V.cm-1的直流电压,运行5 d后,相比在阳极单纯添加沸石或Fe0可渗透反应层,添加"Fe0+沸石"反应层能在最大程度上减小阳极土壤pH值的波动,可将土壤pH值控制在5.5～8.5范围内,土壤中任意位置Cr(Ⅵ)的去除率可提高到97%以上,土壤中残留的Cr(Ⅲ)更少,可渗透反应层对Cr的截留量可分别提高8倍和1.8倍,并将98%的Cr(Ⅵ)转化为低毒的Cr(Ⅲ).研究结果为开发具有实用意义的可渗透反应复合电极修复技术提供了理论依据.