Detection of non-sea salt sulphate aerosol at a remote coastal site in South Africa: A PIXE study

An aerosol sampling site based on a single-stage streaker sampler with four-hour time resolution was established in 1993 at Brandt-se-Baai, on the north-western coast of South Africa (31.5°S 18°E, 50 m asl). The site was deployed to monitor the generation of dust from the local mining operations and in part to test the hypothesis of large-scale air mass recirculation over Southern Africa. Streaker samples were analysed by PIXE for the usual crustal derived elements and sulphur. Sulphate aerosols over southern Africa are produced in the atmosphere by oxidation of SO₂, from industry, or DMS, from the ocean. Industrial related sulphate plays a key role in tracing long-range transport of anthropogenic pollutants.

We present results from selected monthly samples collected during 1996. Measured particulate sulphur has been apportioned between contributions from sea spray and non-sea salt sulphate (NSS) aerosols. Marine particulate sulphur, present in the regional background, was traced by its correlation with Na and Cl, which were routinely detected. The NSS content of these air masses was enriched with respect to the expected sea salt sulphur by two orders of magnitude. Al, Si, K, Ca, Ti and Fe, the major crustal elements, were measured only episodically with the occurrence of strong south-easterly winds. These winds are associated with wind blown dust from a mine located 4 km from the site.

These results are the first direct aerosol characterisation of the remote region of the western seaboard of southern Africa. Specifically the sulphur measurements at this site provide insights into relative contributions of natural DMS, industrial and sea salt contributions of particulate sulphate.     

Manganese survey in airborne particulate matter from a mining area at Hidalgo State, Mexico

A manganese (Mn) survey in airborne particulate matter from a mining area located in Hidalgo State (Mexico) was performed using PIXE. Deposits of Mn ore, first discovered in 1959 and under continuous exploitation since 1962, are nowadays considered as one of the most important of their kind in the American Continent. Afterwards, local inhabitants have been under continuous overexposure to dusts and water highly enriched with Mn. Since no information was available about Mn content in airborne particulate matter in that area, especially in the respirable fraction PM_2.5, airborne particles were collected simultaneously at two sites located on opposite sides of the rim of the mining valley, and along the line of prevailing local winds. The sample collection was performed on eight alternate days, taking two samples per day (day-time and night-time) at each sampling site, using Stacked Filter Units (SFUs) of the Davis design to separate particles into fine (PM_2.5) and coarse (PM₁₅) sizes. The samples were PIXE analyzed and the results of this study revealed that Mn content, in both fine and coarse fractions, were in excess of the general urban background level of 40 ng/m³ (US Environmental Protection Agency, 1990) in more than 50% of the samples, which indicate severe environmental deterioration in the place under study.     

Pollution effects on stone benches of the Eagle Warriors Precinct at the Major Temple, Mexico City

During Major Temple archaeological site excavations in Downtown Mexico City, the precinct of one of the most important Mexica military caste, the Eagle Warriors, was discovered. The ceremonial enclosure is composed of three rooms surrounded by paintings on 11 stone benches placed against the walls. Nowadays, these paintings and the stones present the effects of different deterioration processes produced by the underground water level, high humidity, and the presence of soil, water, and air pollutants. Ion beam analysis of samples from the benches and wall paintings was performed using PIXE and RBS techniques. Using enrichment factors of elements relative to iron concentrations, possible contamination by sulfur and chlorine salts was found, as well as airborne zinc scavenged by rain.     

新型自流平修补砂浆的性能与制备

通过材料、配合比的优化,成功制备出新型自流平修补砂浆.该材料具有良好的工作性,且扩展度大,经时损失小,凝结时间适宜,利于施工.并具有微膨胀性,抗裂性好.28d抗折、抗压强度分别达15.2、80.1MPa.研制的界面剂优于传统掺膨胀剂的界面剂,28d粘结强度可达7.8MPa.     

洗煤厂用滤布激光自动切割机的设计与应用

为了解决洗煤厂用滤布传统人工裁剪加工造成的劳动强度大、效率低、精度差、裁剪损耗较多等问题,通过设计研发激光滤布自动切割机,代替了传统手工裁剪,实现了全程自动化作业,做到了高效率、高精度、低损耗地切割滤布,实现了减人增效和提效增效。     

浅谈快速而规范检定电子汽车衡的技巧

随着电子汽车衡应用范围和量的不断扩大,使检定工作任务量也越来越重.文章结合作者在本单位实际检定工作的具体做法,介绍了在严格按照国家检定规程检定电子汽车衡的过程中能既快又好的完成检定工作的技巧.     

三峡升船机坝段上闸首地基f548断层化学灌浆处理

三峡工程左岸升船机坝段(升船机上闸首)属通航建筑物,闸首结构特殊、受力复杂,地基存有性状较差的f548断层对闸首结构受力和变形影响不利.设计决定除采取部分挖除、掏挖然后用混凝土置换和抽槽回填等方法处理外,还对断层进行化学灌浆处理.文章仅介绍断层化学灌浆处理的方法与效果.     

洞巴面板堆石坝安全监测设计综述

文章介绍广西百色洞巴水电站面板堆石坝安全监测设计原则、监测项目及监测仪器布置,对采用软岩筑坝的面板堆石坝安全监测设计及实施有一定的参考作用.     

Cr-Fe-C合金镀层的电化学磨蚀行为研究

利用新开发的从Cr^3 水溶液中电镀非晶态铬合金的新工艺,在铜合金基体上获得了厚度30μm以上的Cr-Fe-C合金镀层。对经不同温度下热处理的镀层进行了显微硬度和XRD分析和腐蚀磨损电化学行为研究。结果表明：该镀层热处理后伴随逐渐向晶态转化可出现明显的硬化现象。钝性的Cr-Fe-C合金镀层在电解质中局部表面受到摩擦作用时,镀层的磨蚀是腐蚀和磨损两种失效形式相互加强和共同作用的结果。与传统的铬及铬合金镀层相比,该镀层可作为经济的耐磨和耐磨蚀镀层使用。