Speciation and fractionation of heavy metals in soil experimentally contaminated with Pb,Cd, Cu and Zn together and effects on soil negative surface charge

Speciation and fractionation of heavy metals in soil subsamples experimentally loaded with Pb, Cd, Cu and Zn in orthogonal design was investigated by sequential extraction, and operationally defined as water-soluble and exchangeable(SE), weakly specific adsorbed( WSA),Fe and Mn oxides-bound(OX) and organic-bound( ORG). The results showed that fractions of heavy metals in the soil subsamples depended on their speciation. About 90% of Cd and 75% of Zn existed in soil subsamples in the SE fraction. Lead and Cu existed in soil subsamples as SE, WSA and OX fractions simultaneously, although SE was still the major fraction. Organic-bound heavy metals were not clearly apparent in all the soil subsamples. The concentration of some heavy metal fractions in soil subsamples showed the good correlation with ionic impulsion of soil, especially for the SE fraction. Continuous saturation of soil subsamples with 0.20 mol/L NH4CI, which is the first step for determination of the negative surface charge of soil by the ion retention method, resulted in desorption of certain heavy metals from the soil. It was found that the percentage desorption of heavy metals from soil subsamples depended greatly on pH, the composition and original heavy metal content of the soil subsamples. However, most of the heavy metals in the soil subsamples were still be retained after multiple saturation. Compared with the parent soil, the negative surface charge of soil subsamples loaded with heavy metals did not show difference significantly from that of the parent one by statistical analysis. Heavy metals existed in the soil subsamples mainly as exchangeable and precipitated simultaneously.     

共沸-分馏连续操作处理醇酮装置酸性废水

为了降低环己醇、环己酮生产装置产生的含甲酸废水的COD,使其达到排放标准,降低废水排放量,减少环境污染的目的,根据共沸-分馏间歇操作处理醇酮装置酸性废水研究获得的工艺参数,采用共沸-分馏连续操作处理该酸性废水,并从中回收甲酸。介绍了共沸-分馏连续操作处理醇酮装置酸性废水的工艺过程、操作方法,给出了共沸-分馏连续操作处理该废水并回收甲酸的实验数据,完成了间歇操作改连续操作过程的工艺研究,研究结论为进一步工业化生产装置设计奠定了基础。通过研究得出,采用共沸-分馏连续操作处理该酸性废水,废水的COD由1.6×105mg/L降至3.0×102mg/L以下,达此标准水为80%以上,废水的COD去除率达到99%以上,甲酸回收率80%,连续操作实验结果优于间歇操作。     

Fractionation of heavy metals in shallow marine sediments from Jinzhou Bay, China

This work investigated the distribution and speciation of Cd, Cu, Pb, Fe and Mn in the shallow sediments of Jinzhou Bay, Northeast China, which has been heavily contaminated by nonferrous smelting activities. The concentrations of Cd, Cu and Pb in sediments were found to be 100, 13 and 7 times, respectively, being higher than the national guideline (GB 18668-2002). Sequential extraction test showed that 39%-61% of Cd were exchangeable fractions, indicating that Cd in the sediments posed a high risk to local...     

稀土元素分馏作用研究进展

本文综述了环境中稀土元素的分馏过程以及分馏作用对其在岩石、土壤、植物、水环境中分布、迁移规律的影响,探讨了引起稀土分馏的机理,为稀土的环境化学研究提供了详实的材料。     

气溶胶稳定硫同位素研究进展

稳定硫同位素可以用来示踪硫酸盐气溶胶的来源、迁移和转化的过程.本文首先介绍了目前气溶胶稳定硫同位素相关的分析测试方法,即EA-IRMS、MC-ICPMS和NanoSIMS.归纳了国内外气溶胶δ34S的时空组成特征,两极和沿海区域气溶胶δ34S值普遍高于内陆区域;冬季燃煤和夏季生物排放作用使得气溶胶δ34S值冬高夏低.同...     

黑柱石和水之间氢同位素平衡分馏的实验研究

在750-250℃温度范围内,对黑柱石-水之间的氢同位素平衡分馏进行了实验研究。研究中改进了氢同位素交换实验方法,从而保证了精度。研究结果表明,750-550℃温度范围内,黑柱石一水的分馏系数10~3lnα°_(黑柱石-水)=-30.51 10~6/T~2-59.86,550-350℃温度范围内,10~3lnα°_(黑柱石-水)与温度1/T~2间无依赖关系,其值为-105.0±0.7,.250℃时,交换率太低。文中讨论了黑柱石-水之间氢同位素分馏系数与温度、矿物晶体结构、矿物化学组成的关系及其地质意义。     

盐城凹陷凝析油地球化学特征

运用碳同位素、气相色谱、色谱 质谱、流体包裹体技术 ,研究了盐城凹陷凝析油地球化学特征 ,并与永安凹陷永 7井凝析油、下扬子海相原油进行了对比。该凝析油碳同位素为 -2 8 8‰～ 3 0 5‰ ,全油色谱中含有一定的长链正构烷烃 ,Pr/Ph为 1 5 6,三环萜烷含量高 ,伽玛蜡烷含量低 ,重排甾烷含量高 ,C2 9甾烷 >>C2 7甾烷 >C2 8甾烷。石蜡指数、庚烷值表明原油为高成熟凝析油 ,甲基菲指数MPI表明原油为未熟—低熟原油 ,C2 9甾烷 2 0S/ (2 0S+2 0R)值表明原油为成熟原油。这种成熟度的差异可能与不同成熟度原油的混合作用有关。油气主要充注时间为 6～ 1 5Ma。凝析油的主体可能源于泰州组烃源岩 ,凝析油的形成与蒸发分馏作用密不可分     

植物中锌同位素的研究进展

锌同位素是示踪植物中锌地球化学的重要手段,详细了解植物中锌同位素的分馏过程是探究其生物地球化学的关键。本文对目前研究程度较高的超富集植物、普通植物的锌同位素分馏成果进行了系统的总结,发现二者锌同位素分馏趋势基本一致,即相比于培养液或土壤的同位素组成,植物根部相对富集锌的重同位素,而植物地上部(如茎、叶等组织器官)相对富集锌的轻同位素。对于能够引起植物发生锌同位素分馏的因素归纳如下:(1)植物根部相对富集锌的重同位素,是土壤中锌的形态、根部对锌的吸收方式、细胞表面吸附共同作用的结果;(2)植物木质部对锌的向上运输,会随着传输距离的增加而使地上部组织器官相对富集锌的轻同位素;(3)大气沉降也可能导致叶片富集锌的轻同位素。     

基于氢氧稳定同位素的地下水循环研究进展

本文简单介绍了氢氧同位素在水文学中的研究进展,氢氧稳定同位素的分馏过程研究和氢氧稳定同位素示踪下水体间水力联系的探究,为氢氧稳定同位素在地下水循环过程提供了研究基础。     

铁同位素方法在环境地球化学研究中的应用与进展

由于同位素分析方法的改进和多接收电感耦合等离子体质谱仪的使用,近年来Fe同位素地球化学研究有了很大进展,成为国际地学领域的一个热点研究方向。Fe在自然界广泛存在,分布于各类矿物、岩石、流体和生物体中,并广泛参与成岩成矿作用、热液活动和生命活动过程。自然界中各类无机过程(从高温到低温)、生物及有机过程均能使Fe同位素发生分馏,δ56Fe值约为-1.62‰～+0.91‰。文章系统介绍了Fe同位素研究的最新进展,包括Fe同位素测试方法简介、样品前处理、质谱测定、Fe同位素分馏机理和应用前景展望等,着重对该技术在环境地球化学、生物示踪、古海洋学研究等领域中的应用及前景做了阐述。