石墨探针直接收集和石墨探针炉原子吸收法测定APM中痕量镉

本文采用多孔石墨探针直接采集大气微粒物质（ＡＰＭ）后，立即用石墨探针炉原子吸收法测定收集在探针上的ＡＰＭ中镉。实验表明，面积吸光度与镉的浓度在０－５０μｇ／Ｌ呈良好线性关系。镉的特征量和检测出限分别为２．４８和１．８６ｐｇ，其相对标准偏 ２．０６％，分析标准参比其回收率和相对标准偏差。分别为９０．１５－９９．２９％和４．０９％。方法准确、灵敏、快速、简便。     

Dynamic Electrical-Mechanical Energy Coupling in Electrolyte-Mineral Systems

Electrical-mechanical and mechanical-electrical coupling phenomena have been observed in geo-materials. Underlying internal phenomena are not always clear. In this paper, we identify potential microscale processes on the bases of previously published research; fundamental physical principles and analytical models are included. Second, we notice important inconsistencies between theoretically predicted values or high-frequency laboratory data with respect to low-frequency field observations. To explore these differences, we conduct a laboratory experimental study that simulates field conditions, placing emphasis on low frequency coupling, that is, less than 10 kHz. Both, mechanical-electrical and electrical-mechanical effects are observed. Finally, hypotheses are presented in an attempt to explain observed differences.     

Bases for predicting gas-particle flows with particular reference to turbomachinery

Advances in the understanding of particle dynamics and their trajectories and the resultant erosion of solid surfaces are reviewed. Particular attention is given to the calculation procedures used in the analysis of gas-particle flows, always with the intention of application to turbo-machines. One, two and three-dimensional analyses are considered and the limitations of each are discussed. As in the analysis of a real fluid flows, resort is made to empirical correlations of many phenomena and, even then, the predictions of particle trajectories are restricted. The correlation and restrictions are discussed where appropriate.     

A Routine Method for the Quantitative Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Urban Air

Abstract

We have developed a method for the quantitative determination of polycyclic aromatic hydrocarbons (PAHs) present in urban air, which can be performed rather quickly, and which uses a minimal amount of solvents.

Air samples were collected using a home-made low-volume air sampler equipped with glass fibre filter and polyurethane foam plugs. After Soxhlet extraction a liquid-liquid partition was carried out to isolate the PAH fraction. This liquid-liquid partition was performed in micro-scale, enabling us to use small quantities of the solvents and to separate the solution layers very rapidly using a centrifuge. Sample clean-up was accomplished on a high performance liquid chromatograph equipped with two normal phase silica columns. The losses of all investigated PAHs occurring during the various steps of sample clean-up have been determined. The qualitative and quantitative determination of the PAHs was carried out by capillary gas chromatography; the results were confirmed by GC/MS measurements.

The analytical procedure described was applied over a period of one year to measure the concentrations of 21 PAHs in the city of Vienna at a site with high traffic density. The concentrations of the four more volatile PAHs were determined on a semi-quantitative basis. The ratio of two selected PAHs was used to estimate the respective contribution of traffic and domestic heating to the total PAH level at the sampling site.     

Recent developments in assessment of bio-accessible trace metal fractions in airborne particulate matter: A review

In the last years a great deal of research has been focused on the determination of harmful trace metals such as Cd, Co, Cr, Cu, Ni or Pb in airborne particulate matter (APM). However, the commonly applied determination of total element concentrations in APM provides only an upper-end estimate of potential metal toxicity. For improved risk assessment it is important to determine bio-accessible concentrations instead of total metal contents. The present review gives an overview of analytical procedures reported for measurement of bio-accessible trace metal fractions in APM. The different approaches developed for extraction of soluble trace metals in APM are summarized. Furthermore the analytical techniques applied for accurate determination of dissolved trace metals in the presence of complex sample matrix are presented. Finally a compilation of published results for bio-accessible trace metals in APM is included.     

黄河口海域悬浮物浓度Landsat8 OLI分段线性反演

黄河每年输送大量泥沙进入渤海。研究黄河口海域悬浮物浓度，对于黄河输沙以及周边海域的环境监测具有重要意义。利用2011年夏、冬两季实测遥感反射率以及同步测量悬浮物浓度数据，开展了黄河口海域悬浮物浓度分段线性反演研究。结果表明，不同浓度范围下，悬浮物浓度反演的敏感波段不同；浓度小于等于50 mg·L-1(≤50 mg·L-1)，敏感比值波段为(600~700 nm)/(400~600 nm)，浓度高于50 mg·L-1(＞50 mg·L-1)，敏感比值波段为(750~900 nm)/(420~720 nm)，Landsat8 OLI的对应组合方式分别为B4/B2和B5/B3；根据上述浓度分段范围分别建立线性模型，其精度R2，RMSE和APD分别为0.873 5，4.08 mg·L-1和22.81%(≤50 mg·L-1)，以及0.969 3，102.96 mg·L-1和17.51%(＞50 mg·L-1)，整个浓度下三个精度参数分别为0.975 3，67.03 mg·L-1和20.45%，均优于常用单一模型在分段和整体浓度下的相应参数，且具有良好的稳定性。分段线性模型，更适合浓度变化大的黄河口海域悬浮物浓度反演。     

Effects of Homogenization Models and Emulsifiers on the Physicochemical Properties of β-Carotene Nanoemulsions

Microfluidization and high pressure valve homogenization were applied to prepare β-carotene nanoemulsions, and the mathematical relationship between homogenization pressures and emulsion temperatures, homogenization pressures/cycles, and droplet sizes, were established. Emulsions through Microfluidizer had lower temperature and much smaller droplet sizes, compared with those through high pressure valve homogenizer. Four emulsifiers were compared for their capacities to stabilize nanoemulsions. The two large molecule emulsifiers, octenyl succinate starch (OSA) and whey protein isolate (WPI), were less effective for the formation of nanoemulsions with smaller droplets than the two small molecule emulsifiers, polyoxyethylene sorbitan monolaurate (Tween 20, TW) and decaglycerol monolaurate (DML). The nanoemulsion containing WPI was the most stable, while the one containing DML was the least stable. During storage, significant degradation of β-carotene occurred in all nanoemulsions, especially in the DML stabilized one, while WPI showed the greatest capacity to protect β-carotene from degradation.     

Analytical Standards and Methods for the Determination of Polynuclear Aromatic Hydrocarbons in Environmental Samplest

Abstract

Standard reference materials (SRM's) have been produced, certified, and issued by the United States National Bureau of Standards (NBS) since 1905. NBS currently issues more than 1000 SRM's of various types, including nuclear materials, rubber, clinical and environmental trace metal standards. The most recent addition to this group is a series of environmental trace organic materials with certified concentrations of selected polynuclear aromatic hydrocarbons (PAH), phenols, and N-heterocyclic compounds. Until recently, trace organic SRM's were non-existent due to the lack of analytical methodology necessary for certification. Details concerning the analytical methods developed and used for certification of the concentrations of several PAH in SRM's 1580 (Organics in Shale Oil), 1644 (Generator Columns for PAH in water), 1647 (PAH in Acetonitrile), and 1649 (Urban Particulate Matter) are given along with some suggested uses for these SRM's.     

大气颗粒物中砷及其形态的研究进展

大气颗粒物中毒性准金属元素砷及其形态含量变化引起的环境健康问题受到了广泛关注。由于工业生产和煤燃烧等人类活动,砷普遍存在于多种环境介质中。排放到大气中的砷能够随气流进行长距离迁移,致使一些偏远区域大气中的砷含量明显超出欧盟的限制标准(6 ng/m3)。砷的毒性表达很大程度依赖其存在种态,无机砷毒性大于有机砷,且砷(Ⅲ)的毒性明显强于砷(Ⅴ)。本文概述了大气中砷的来源,并选取自2000年来的代表性成果比较了不同国家及不同功能区大气砷的含量变化,同时对1975年来多数关于大气颗粒物中砷形态变化特征的研究进行了评述。