偶氮胂Ⅲ褪色光度法测定土壤中的铬   总被引：1，自引：1，他引：0  

王蓉  张丽萍  邹时英 《岩矿测试》2011,30(2):230-232

偶氮胂Ⅲ是一种稀土显色剂,利用Cr(Ⅵ)的氧化性使偶氮类试剂褪色而建立的褪色光度法测定铬是目前的研究热点之一。文章基于在硝酸介质中,偶氮胂Ⅲ与Cr(Ⅵ)发生灵敏的褪色反应,建立了褪色光度法测定土壤中铬的方法。褪色体系△A的最大吸收波长为545 nm,摩尔吸光系数为4.67×104 L/(mol.cm),Cr(Ⅵ)的质量浓度在0～0.8μg/mL内符合比耳定律。建立的方法用于土壤中痕量铬的测定,测定值与原子吸收光谱法结果一致,6次测定的相对标准偏差(RSD)小于3.1%,方法回收率为98.6%～102.6%。方法精密度好,准确度高。  相似文献   

The effect of valence state and site geometry on Cr L3,2 electron energy-loss spectra of Cr-bearing oxidic compounds     

《Chemie der Erde / Geochemistry》2014,74(3):497-505

Chromium L_3,2 energy loss near-edge structures (ELNES) of nine chromium compounds were measured in a transmission electron microscope to study the effect of valence state and site geometry of chromium on spectral features. The compounds studied represent a set of standards with given valence state and coordination. The chromium coordination is either octahedral or tetrahedral with different degree of distortion. The distortion of polyhedra results in a loss of the fine detail of spectral features in Cr L_3,2 ELNES spectra. The effect of valence state manifests in a systematic chemical shift of the ELNES spectra by about 2 eV per oxidation state for octahedrally coordinated Cr and 0.4–1.4 eV per oxidation state for tetrahedrally coordinated Cr. On the basis of collected Cr L_3,2 ELNES spectra we propose a simple quantification technique for the determination of chromium oxidation state in oxidic compounds which is independent of the coordination.  相似文献   

北祁连拉硐超基性岩体铬尖晶石特征研究及找矿意义     

徐均强  徐伟祥  杜韦  崔灿 《山东地质》2014,(4):49-54

拉硐超基性岩体位于青海省祁连县城东北约15 km处,面积约7．6 km2,岩性主要由蛇纹石化橄榄岩、蛇纹石化辉榄岩、蛇纹岩及纯橄岩组成,共发现157个铬铁矿小矿体,铬铁矿体成群出现,依据野外铬铁矿体分布范围,自西向东划分为10个矿带,通过对其中铬尖晶石取样分析研究,并与区内其他含矿岩体中铬尖晶石样品化验分析结果对比,确定该类岩体不同岩性组合带的找矿方向。  相似文献   

胶州湾水域重金属铬的分布及迁移     

杨东方  高振会  孙静亚  曹海荣  刘向群 《海岸工程》2008,27(4):48-53

根据1979年的胶州湾水域调查资料，分析了重金属铬在胶州湾水域的分布、迁移和季节变化。研究结果表明；春季，胶州湾水城铬污染较轻，大部分海域水质状况较好，而到夏季没有受到污染。在时空分布上，春季，铬污染形成了明显的梯度，由东北向西南方向递减，从112．3μg／L降低到0．2μg／L。夏季，铬的水平分布比较均匀，表层水体铬的含量较低，范围在0．10～1．40μg／L之间波动。因此认为，1979年整个胶州湾水域的重金属铬属于面污染源。而且，当铬进入胶州湾海域后，很快吸附在水体中的悬浮颗粒上，并被水流较快地带离胶州湾水城，几乎没有在胶州湾水域表、底层留下污染痕迹。  相似文献   

Identification and mapping of chromium (VI) plume in groundwater for remediation: A case study at Kanpur,Uttar Pradesh   总被引：1，自引：0，他引：1  

R. K. Singh  B. Sengupta  Rameshwar Bali  B. P. Shukla  V. V. S. Gurunadharao  Rajesh Srivatstava 《Journal of the Geological Society of India》2009,74(1):49-57

With only twenty five percent population living in urban areas, India has cities amongst the biggest in the world. Urban growth in most of Indian cities is concomitant with rise in water demand for community, as well as, for industrial purposes. The complex situation resulting from indiscriminate disposal of waste and its severe impact on groundwater quality is set for continuous worsening mainly for want of sustained effort aimed at site-specific remediation. The study, a prerequisite for actual remediation in an industrial city of Kanpur, India, envisages detailed investigation about pollutant transport, evaluation of concept of Bio-remediation and a range of other options and finally full scale implementation of the best suited. Drilling of piezometers and resistivity survey indicates that the area is constituted of alluvial sands, gravels and their various admixtures. Chemical analysis of water samples collected from piezometers and hand pumps shows the presence of hexavalent chromium rich horizons at various depths. The alarming concentration of this carcinogenic heavy metal of the order of 16.3 mg/l against the permissible concentration (of 0.05 mg/l) for drinking water and high concentration within sediments of the area poses a major threat to the entire ecosystem. The projection of migration contaminant plume of hexavalent chromium as depicted in the paper is indicative of a concentrated extent of core zone existing in shallow alluvial aquifer, which may be targeted for interception by remedial measures. The present work, elaborating on the source, potential and monitoring the migration of the pollutant plume is the first field scale study of its kind in the country. The findings of these studies are of strong relevance in addressing the ground water pollution due to indiscriminate disposal practices of hazardous waste in areas located within the alluvial zones.  相似文献   

稳定同位素53Cr在地下水污染研究中的应用   总被引：2，自引：2，他引：2  

高永娟  马腾  刘存富  蔡鹤生 《地球学报》2005,26(Z1):296-298

铬是地表水和地下水中的常见污染物，它被广泛应用于电镀、制革和防腐。在氧化条件下，Cr以Cr(Ⅵ)的阴离子铬酸盐（CrO2-4）和重铬酸盐（HCrO-4）形式存在，有很高的溶解性和流动性。Cr(Ⅵ)是一种可疑的致癌物。在还原条件下，Cr的分馏。所有地下水Cr(Ⅲ),它不溶解，并且强烈地吸附在固体表面上，而且毒性很小。Cr(Ⅵ)的还原作用可导致Cr稳定同位素轻同位素。因此，稳定铬同位素比值可以用作地下水中Cr(Ⅵ)还原程度的指示剂。笔者使用方程（1）确定了两个地下水样（MW-6和MW-12）的还原程度，它们分别为31%和68%。  相似文献   

微生物矿化机制研究中的介观分析技术——以微生物与六价铬相互作用为例   总被引：1，自引：0，他引：1  

栗斌  程扬健  马晓艳  王永好  郑晋生  储旺盛  吴自玉  林璋 《高校地质学报》2007,13(4):651-656

微生物矿化的微观机理研究是当前地质微生物学的研究热点之一。以苍白杆菌与铬相互作用的研究为例,阐述了各种介观方法在微生物矿化模拟实验及微观机理研究中的应用。该研究借助透射电子显微镜、扫描电子显微镜、原子力显微镜以及X射线吸收精细结构谱(XAFS)等表面与纳米表征手段,获得了铬还原菌与六价铬作用过程中的微观结构信息,包括菌体的形貌变化、铬在菌体内外的分布和成晶情况、非晶态还原产物的离子价态以及局域配位环境。研究结果将有利于揭示微生物与重金属相互作用机理,对其它类似体系的研究亦有借鉴意义。  相似文献   

Sensitivity of estuarine phytoplankton to hexavalent chromium     

Bruce E. Frey  G.Fritz Riedel  Ann E. Bass  Lawrence F. Small 《Estuarine, Coastal and Shelf Science》1983,17(2):181-187

Experiments were conducted in which we tested the effects of hexavalent chromium on both natural assemblages of phytoplankton and cultures of Thalassiosira pseudonana clone 3H. Water was collected from various locations in Yaquina Bay, Oregon, with salinities ranging from 32·5‰ to 0·03‰. A variety of nutrient regimes were tested by adding major nutrients and micro-nutrients, and/or stripping micro-nutrients with activated carbon. In one high salinity experiment, chromium was stimulatory, as were micro-nutrient additions. In other high and medium salinity experiments, chromium was neither stimulatory nor inhibitory, at levels up to 1·9 μ mole l^?1 Cr. There was, however, slight inhibition of growth at 19·0 μ mole l^?1 Cr, due specifically to inhibition of Skeletonema costatum. In our freshwater experiments, chromium was very inhibitory at 1·9 μ mole l^?1 Cr, and slightly inhibitory at 0·19 μ mole l^?1 Cr. Species inhibited by chromium were Surirella ovata, Detonula confervacea, and Cyclotella sp. Experiments were conducted with T. pseudonana grown over a wide range of salinities. Chromium was found to be very inhibitory in freshwater and became progressively less toxic as the salinity increased. Most inhibition was neutralized by a salinity of 2·1‰.  相似文献   

AMA吸附剂吸附铬(Ⅵ)的性能研究及应用   总被引：2，自引：0，他引：2  

宋金如范桂英  蒋小良 《华东地质学院学报》2004,27(3):271-276

用凹凸棒石粘土改性制备了AMA吸附剂，对其吸附铬(Ⅵ)的性能进行了较系统地研究。选择了吸附铬(Ⅵ)的最佳条件，用来处理含铬(Ⅵ)废水，铬(Ⅵ)的去除率在96％以上，铬(Ⅵ)的残余浓度小于0．5mg/L，符合国家的排放标准。可以在废水治理中推广应用。  相似文献   

二安替比林基—（3,4—二甲氧基）苯基甲烷光度法测定微量铬   总被引：5，自引：0，他引：5  

曹秋娥  杨晓云 《岩矿测试》1993,12(4):277-279

合成和鉴定了二安替比林基－（３，４－二甲氧基）苯基甲烷，并研究了其与Ｃｒ的显色条件。在Ｍｎ存在下，试剂与Ｃｒ反应生成橙黄色产物，λｍａｘ＝４６５ｎｍ，ε＝８．４５×１０＾５Ｌ·ｍｏｌ＾－１·ｃｍ＾－１，Ｃｒ量在８－５６ｎｇ／ｍｌ范围内符合比尔定律。该体系稳定时间在３ｈ以上，重现性好，用于电镀废液及球铁中Ｃｒ的测定，结果满意。  相似文献