USE OF X-RAY FLUORESCENCE TO DETERMINE TRACE METALS IN WATER RESOURCES1

ABSTRACT. The X-ray fluorescence method was used to analyze trace metals collected in particulate form on filter papers and from the ionic state by ion exchange filter papers. The samples were prepared by allowing water to pass through these filter papers. The procedures necessary for using the X-ray fluorescence method are described. A number of samples were taken from the Great Miami River in Dayton, Ohio over one year showing the presence of the following metals, Ca, Ti, Cr, Fe, Cu, Zn, Sr, and Cd. Elements in the periodic table between Ti and Cs were detectable to a sensitivity limit of the order of 30 ppb for metals in the particulate form and 0.4 ppm for metals in the ionic form.     

基于分形维数的斜坡非饱和带土体大孔隙分布研究

对取自于云南省昭通市头寨滑坡滑源区附近的两个大尺度(25cm×25cm×50cm)土柱样品进行CT扫描,选取典型剖面切片,通过CT值范围将大孔隙分离从而研究土体中的大孔隙分布;计算大孔隙分布分维数(盒维数),研究其大孔隙的不规则特征,结果表明:土体中大孔隙的盒维数随深度增加呈单调递减规律,且与大孔隙度具有显著正相关关系;但大孔隙度只能表征在某一深度上大孔隙的分布多少,而大孔隙的不规则特征则需盒维数表征;最后得到大孔隙的累积大孔隙度与大孔隙孔径(在盒维数为常数时)符合幂函数规律,研究结果有利于利用分形理论建立大孔隙模型,从而研究水分在大孔隙中运动过程。     

水环境中的碘化X-射线造影剂及其去除工艺研究进展

碘化X-射线造影剂(Iodinated X-ray contrast media,ICM)在水环境中被广泛检出,因其近期被发现是碘化消毒副产物的前体物而受到越来越多的关注.本文总结了ICM在污水、地表水和饮用水等水环境中的污染现状;分析了ICM的转化产物及转化机制;重点介绍了ICM的去除工艺,包括高级氧化技术、辐射技术以及生物降解转化技术;讨论了ICM及其降解转化产物可能对环境造成的生态风险.最后,本文对未来ICM的研究前景进行了展望.     

氯化铁絮凝-直接过滤工艺对地下水中As(Ⅴ)的去除机制研究

为探明氯化铁(Fe Cl3)絮凝-直接过滤工艺对地下水中砷(As)的去除过程及机制,分别进行了批吸附实验、现场絮凝-直接过滤实验、扩展X射线精细结构光谱(EXAFS)及电荷分布多位络合(CD-MUSIC)模拟.采集的地下水样品As主要为五价[As(Ⅴ)],浓度为40μg·L-1.现场柱实验直接过滤工艺中Fe投加量为1.5 mg·L-1,出水As(Ⅴ)浓度均低于10μg·L-1,92 h内可提供64 984 L安全饮用水.固体废物毒性浸出实验表明泥饼浸出液中As浓度为3.4μg·L-1,远低于美国环保署限定值(5 mg·L-1).EXAFS和CD-MUSIC模拟表明Fe Cl3絮凝去除地下水中As(Ⅴ)存在两种机制:在p H 3~9.5范围内,As(Ⅴ)主要以双齿双核吸附在氢氧化铁上;p H9.5时,As(Ⅴ)主要与Ca2+和Mg2+形成沉淀而去除.     

广西涠洲岛沉凝灰岩土壤粘粒矿物的研究

用X射线衍射分析和电子显微镜分析,对涠洲岛沉凝灰岩母质发育土壤的两个典型剖面八个土样的粘粒矿物进行分析研究。结果表明,离火山口距离不同的两个剖面土壤粘粒矿物组成不同,1号剖面以2:1型粘粒矿物为主,2号剖面则以1:1型粘粒矿物为主;结合其它分析结果,讨论了两个剖面土壤粘粒矿物组成不同的原因、对土壤有关特性的影响及其与土壤形成和分类的关系。     

X－射线荧光光谱法测定道路扬尘中21种元素

本文用Ｘ－射线荧光光谱法，一次测定道路扬尘中Ｎａ等２１种元素。人工配制标样，回归法求取校准曲线常数，用散射线内标法和经验系数法校正基体效应。方法的准确度、精密度较好，分析结果令人满意。     

A Preliminary Study of Geographic Influence on Arsenic Concentrations in Human Hair

Past mining activities in the county of Cornwall in the United Kingdom, has exposed the local environment to raised levels of As. Previous research has shown an increased concentration of As in crops grown in such areas and the subsequent take-up of As through the food chain may lead to an increased body burden in man. In an attempt to evaluate this, a pilot study was carried out using Particle Induced X-ray Emission to compare the hair As concentration of a group of Cornish residents to that of a control group consisting of residents in the counties of Oxfordshire and Wiltshire. The null hypothesis being that there is no significant difference between the hair As concentrations of the two groups.Each group comprised thirty six age and sex matched subjects. The mean hair As concentration for the Cornish group was 2.51 g g-1, which is significantly greater than that of 0.7 g g-1 found in the control group (p = 0.004). The World Health Organisation suggests a hair As value greater than 1 g g-1 as evidence of increased exposure to As and 5 g g-1 is quoted by the Canadian Government as evidence of significant ingestion of As. Twenty one Cornish subjects registered a value at or above 1 g As g-1 compared to nine in the control group (p = 0.0003). Five subjects in the Cornish group had values that exceed 5 g As g-1, compared to only two in the control group (p = 0.23). We use the results of this study as evidence to support our continued work in this area in order to evaluate possible health implications.     

Seasonal variation and chemical composition of particulate matter: A study by XPS, ICP-AES and sequential microanalysis using Raman with SEM/EDS

During the winter period (January–March 2016), the total suspended particles (TSP) and particulate matter smaller than 2.5 μm (PM_2.5) were characterized by the application of various analytical techniques in four zones of the Metropolitan Area of Monterrey in Mexico. To evaluate the seasonal variation of some elements in the particulate matter, the results of this study were compared with those obtained during the summer season (July–September 2015). The speciation of the C_1s signal by X-ray photoelectron spectroscopy revealed the contribution of aromatic and aliphatic hydrocarbons as the main components in both seasons. Conversely, carboxylic groups associated with biogenic emissions were detected only in winter. The percentages of SO₄^2 ? ions were lower in winter, possibly caused by the decrease in the solar radiation, and relative humidity recorded. The results of the ICP analysis revealed that Fe, Zn and Cu were the most abundant metals in both TSP and PM_2.5 in the two seasons. There were significant seasonal variations for concentrations of As, Ni and Zn in the urban area and for Fe, As, Cd, Ni and Zn in the industrial zone. This was attributed to the greater burning of fuels as well as to an increase in vehicular traffic, the effect of thermal inversion and changes in some meteorological parameters. The results of the sequential microanalysis by Raman spectroscopy and SEM/EDS allowed observation of deposits of carbonaceous material on the particles and to perform the speciation of particles rich in Fe and Pb, which helped infer their possible emission sources.     

Atmospheric lead pollution in fine particulate matter in Shanghai, China

The Pb-monitoring program was extended for 6 years from 2002 to 2007 at 17 representative urban sites (6 traffic, 5 industrial, and 6 residential sites), and 3 suburban sites to assess the lead pollution in fine particulate matter (PM2.5) after phasing out leaded gasoline in Shanghai. Compared with Pb levels reported in other places, the Pb pollution in Shanghai is still serious after phasing out leaded gasoline, which remains at high concentration range (213–176 ng/m3) in PM2.5 in winter. Significant spati...     

黑钨渣的酸分解与萃取工艺优化研究

采用X—射线荧光和粉末衍射分析了钨渣的元素组成及赋存方式,采用酸分解—萃取工艺富集了钨,研究了最佳的酸分解—萃取工艺条件。