铬污染及其生态效应

阐述了环境中铬及其化合物的产生、存在形态和转化,对铬及其化合物的危害机理和生态效应进行探讨。     

湖北黄石市天然水铬污染及其同位素特征

元素Cr(Ⅵ)作为水体中重要的污染物质,其同位素组成对水体环境变化具有较强的敏感性.笔者以黄石振华有限公司周围污染水体为分析实例,通过研究发现:在靠近铬渣堆附近的水中,受到的污染较为严重,随着距离的增大,污染程度减小;同时δ63Cr具有较好的指示意义,δ63Cr值基本上随着Cr(Ⅵ)浓度的增大而呈现逐渐减小的趋势.     

Differential Pulse Polarographic Analysis of Lead and Chromium Content in Louisiana Waters

In this investigation, polarographic analyses of water, sediment, and animal samples from Devil's Swamp near Baton Rouge, Louisiana, have been conducted. The focus of this work has been on detection of lead and chromium levels. Lead has been found to be relatively uniformly distributed among the various size fractions of the sediment and is present at a mean level of 18.7 µg g^-1. In the water the concentration is about 15 µg L^-1 of which 75% is bound in suspended particulates and the remainder is dissolved. Preliminary results indicate that more chromium than lead is present in bone and muscle of bullfrogs, and, for each metal, there is a higher concentration in muscle than bone. The mean lead muscle tissue concentration is 550 µg kg^-1, which suggests that bioaccumulation of this metal is occurring, assuming that water contact or ingestion are the main routes of exposure. An important aspect of this research has been optimizing polarographic methodology for performing chromium speciation studies. Methods for determining the amounts of hexavalent and trivalent chromium in mixtures containing the two have been developed.     

硝化褐煤对铬离子溶液的吸附研究

利用硝酸与龙口褐煤反应制得硝化褐煤,使其有效吸附质腐植酸含量提高。用该湖化褐煤对铬离子进行吸附试验,研究吸附剂的吸附量、吸附动力学、吸附模型和溶液的pH值对吸附的影响。结果表明：硝化褐煤对铬离子具有良好的吸附特性,其静态等温吸附符合Langmuir等温议程。     

微波消解-原子吸收/原子荧光光度法测定活性污泥中的Cd、Pb、Ni、Cu、 Zn、Cr、K、As、Hg

通过实验,建立了活性污泥中金属和重金属的测定方法。活性污泥样品经硝酸—氢氟酸或硝酸—高氯酸微波消解处理后,Pb、Ni、Cu、Zn、Cr、K选用火焰原子吸收分光光度法测定,Cd用石墨炉原子吸收分光光度法测定,As、Hg用原子荧光光度法测定。该方法操作简单,结果准确,重现性好。样品加标回收率为93%-108%,相对标准偏差〈5%。     

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.     

酸雨淋溶对铬渣中Cr6+释放的影响

采用人工柱对3个不同年代的铬渣进行为期5年不同pH值(4.0,5.0,6.0)下的模拟酸雨淋溶实验,结果表明:淋溶前铬渣具有很强的腐蚀性,pH值达到12以上,总铬和Cr6 分别占铬渣的4.68%-4.86%和1.19%-1.73%;Cr6 溶出浓度在淋溶初期大,随着淋溶时间的增加,溶出浓度急剧下降,淋溶接近第二年雨量时,溶出浓度减小且趋于稳定.5年模拟酸雨淋溶后,Cr6 累积溶出范围在2138-4490mg,浸出液浓度稳定范围50-127mg·l-1,仍然远高于排放标准.铬渣淋溶后,残渣态和结晶铁锰氧化物结合态铬含量保持不变,水溶态、酸溶态和稳定铁锰氧化物结合态铬有不同程度减小.     

Determination of total chromium by flame atomic absorption spectrometry after coprecipitation by cerium (IV) hydroxide

A method for the preconcentration of the total chromium based on coprecipitation with cerium (IV) hydroxide is proposed for determination of chromium by flame atomic absorption spectrometry. Different factors including carrier element amount, pH, sample volume and matrix ion effects for the precipitation were examined. The detection limit of the total chromium (k = 3, N = 15) was 0.18 μg l⁻¹. The presented method was applied for the determination of chromium in the wastewater samples from Kayseri and Nigde Organized Industrial Region-Turkey and in drinking water from our laboratory, Kayseri with satisfactory results (relative standard deviations below 8%, recoveries 95%). The analytical results obtained by the proposed method for certified copper sample was in good agreement with the certified value.     

中国含铬废物的来源、区域分布和处理现状及监管建议

根据2010年全国污染源普查动态更新调查数据,全面分析了中国含铬废物的来源、区域分布和综合利用、处置、贮存等几种主要处理方式的现状,总结了中国含铬废物重点监管的行业和区域,为环境管理部门重点监管六价铬风险源提出了科学建议。