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231.
生物矿化针铁矿吸附铬的机理探讨 总被引:4,自引:0,他引:4
针铁矿在自然界中广泛存在,对重金属离子在地表的迁移和转化有重要影响.利用天然生物矿化针铁矿进行了Cr(Ⅲ)吸附研究,并利用扫描电子显微镜(SEM)和X射线光电子能谱(XPS)等对吸附后的样品进行表征,发现样品中铬的含量随着Al2O3含量的增加而增加,说明表面带负电荷的含高岭土等的粘土较针铁矿对Cr(Ⅲ)有更强的吸附能力.样品的XPS研究表明,NO3-也参与了反应,且促进了Cr(Ⅲ)的氧化.研究还发现,Cr(Ⅲ)在针铁矿上的吸附不均匀,与文献报道的情况不同. 相似文献
232.
在酸性条件下,水样中的六价铬能够和显色剂二苯碳酰二肼反应生成紫红色络合物,该络合物溶液用自制的数字图像比色装置测定颜色值实现六价铬的现场快速检测.该方法在0.05 mg/L~1.00 mg/L范围内线性良好,方法检出限为0.02 mg/L,标准溶液10次测定结果的RSD为1.6% ~7.9%,实际水样加标回收率为94.... 相似文献
233.
铬污染土壤中六价铬的测定 总被引:8,自引:0,他引:8
研究了土壤中Cr^6+的提取测定方法。结果表明,用0.4mol/L KCl为提取剂,离心分离提取液,可简单,快速,准确地测定土壤中Cr^6+,所建立的方法适用于北方偏碱性土壤。 相似文献
234.
Response of soil catalase activity to chromium contamination 总被引:3,自引:0,他引:3
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. 相似文献
235.
外源Cr(Ⅲ)在我国22种典型土壤中的老化特征及关键影响因子研究 总被引:3,自引:1,他引:3
老化过程对土壤重金属有效性和毒性起着关键性作用.由于我国土壤类型的复杂性,目前对于我国土壤中铬(Cr)的老化过程、转变速率及影响Cr在土壤中老化的关键因子仍然不清楚.本研究选取了全国22种典型土壤,使用0.01 mol.L-1CaCl2作为有效态提取剂,研究我国典型土壤中外源Cr(Ⅲ)的老化过程及影响因子,为准确评价重金属污染的生态环境风险提供科学依据.结果表明,有效态Cr含量随时间先是快速下降,然后缓慢持续降低.在培养期间的前21 d下降速率快,而以后则变化比较缓慢.Elovich方程可以有效拟合有效态Cr在我国22种典型土壤中转化的动力学过程,方程的斜率参数可以作为Cr在土壤中老化速率的表征参数,并用它来比较不同土壤中Cr的老化速率快慢.老化速率与土壤性质的逐步回归分析结果表明,土壤性质中对老化速率影响最大的是有机质,其次是pH和活性氧化铁. 相似文献
236.
237.
238.
用二氧化硫处理含铬废水 总被引:7,自引:2,他引:5
采用二氧化作还原剂,处理高浓度大流量含铬废水,除铬效果良好,进水中产价铬含量为90.0-430.8mg/L时,经还原,沉淀处理后,出水中六价铬含量均可达到排放标准,该工艺基本上实现了二氧化硫的闭路循环,排放尾气中二氧化硫含量〈15mg/L。 相似文献
239.
240.
Herpin U Siewers U Markert B Rosolen V Breulmann G Bernoux M 《Environmental science and pollution research international》2004,11(1):57-66
This paper shows the geographic distribution in Germany of iron (Fe), nickel (Ni) and lead (Pb) analyzed in mosses in 1995/96 and compares it with the results of the 1990/91 pilot study within a European moss-monitoring programme. Other elements (As, Cd, Cr, Cu, Ti, V, Zn) are compared on basis of the overall element medians for Germany of the 1990/91 and 1995/96 survey. Samples of Pleurozium schreberi, Scleropodium purum, Hypnum cupressiforme and Hylocomium splendens were taken at a total of 1026 sites. In the 1995/96 monitoring campaign, 95% of the original sites of the 1990/91 study were resampled. The results from 1995/96 display local elevated values and many cases of areas affected by known sources of heavy-metal emissions. The industrialized and urban regions of Germany are shown up clearly by the 1995/96 moss-monitoring results: the Ruhr area, parts of Saarland and Baden-Württemberg, as well as areas in eastern Germany. Relatively low values for many elements were found in large areas of Lower Saxony and Bavaria. A comparison of the results of the 1990/91 and 1995/96 moss-monitoring programmes shows a fall in the concentration of the presented elements (except cadmium, copper and zinc) over the relevant period. Especially in the former GDR, chromium (Cr), iron (Fe), titanium (Ti) and vanadium (V) decreased significantly. This is, firstly, a reflection of the closure of and/or technological improvements to large power plants; secondly it is due to the fact that lignite has given way to other fuels. Vanadium (V) and nickel (Ni), typical constituents of crude oil, also show a decrease in the western part and thus document changes in the type of fuel consumed. The significant fall in lead concentration in 1995/96 as compared to 1990/91 in what used to be East and West Germany probably results from the increasing use of lead-free petrol. A comparison of the median values for 1990/91 and 1995/96 in mosses to the rate of emission of heavy metals in Germany for 1990 and 1995 shows similar trends in the case of elements such as arsenic (As), chromium (Cr), nickel (Ni), and lead (Pb). The comparison of the medians of the elements analyzed for 19 European countries indicates for most of the elements a general tendency to lower values in 1995, except for Lithuania, Netherlands, Portugal, Italy and United Kingdom. 相似文献