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Sampling campaign was conducted over six weeks to determine particulate matter (PM) concentrations from Sydney Trains airport line (T2) at both underground and ground levels using DustTrak. Dust samples were collected and analysed for 12 metals (Fe, Ca, Mn, Cr, Zn, Cu, Pb, Al, Co, Ni, Ba and Na) by atomic emission spectroscopy. Average underground PM10 and PM2.5 concentrations from inside the trains were 2.8 and 2.5 times greater than at ground level. Similarly, PM10 and PM2.5 concentrations on underground platforms were 2.7 and 2.5 times greater than ground level platforms. Average underground PM concentrations exceeded the national air quality standards for both PM10 (50 µg/m3) and PM2.5 (25 µg/m3). Correlation analysis showed a strong to moderate association between PM concentrations at ground level and background PM concentrations (r2 from 0.952 to 0.500). The findings suggested that underground PM concentrations were less influenced by the ambient background than at ground level. The metal concentrations decreased in the order of Fe, Cr, Ca, Al, Na, Ba, Mn, Zn, Cu, Ni, Co and Pb. The pollution index (PI) and enrichment factor (EF) values were calculated to identify the levels and sources of contamination in the underground railway microenvironments. PM was remarkably rich in Fe with a mean concentration of 73.51 mg/g and EF of 61.31, followed by Ni and Cr. These results noticeably indicated a high level of metal contamination in the underground environments, with the principal contribution from track abrasion and wear processes. 相似文献
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A. Karageorgis Ch. Anagnostou A. Sioulas G. Chronis E. Papathanassiou 《Journal of Marine Systems》1998,16(3-4)
This work aims at studying the geochemistry and mineralogy of Milos bay surface sediments. The bay forms an enclosed marine area, supplied totally by volcanic formations. Totally 16 samples were subjected to sedimentological (grain size), mineralogical (microscope examination and X-ray diffraction of the bulk sample and the pelitic fraction), and geochemical analyses (X-ray fluorescence in the pelitic fraction). Also the carbonate content was determined. Sediments were sandy with a high carbonate content (14–58%). The dominant minerals recognized in the pelitic fraction were smectite, kaolinite and illite, followed by chlorite, quartz, calcite, Mg-calcite and feldspars. In general, element concentrations appeared to be within the normal range, except Pb and Zn, which exhibited relatively high values. The Index of Geoaccumulation Igeo was computed, in order to investigate a possible enrichment of the surface sediments in metals. The analysis revealed again high values of Igeo class for both Pb and Zn. A careful study of the area, in relation to the quality of the catchment basins petrology, lead to a non-anthropogenic origin of these high concentrations. The enrichment of the surface sediments in Pb and Zn is attributed to the weathering of several mineral deposits, pyroclastic rocks and lavas, covering almost all Milos vicinity. A study of the geochemical data correlation coefficient matrix revealed three major groups of elements: (i) the elements of detrital origin represented by Si, Al, K and a part of the metals; (ii) the carbonates group; and (iii) a Fe–Mn oxyhydroxides–oxides group, which attracts a part of Pb, Cr and Ni. 相似文献
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烧结机破碎辊的单(双)齿是承受高温冲击磨损的工件.本文对其堆焊层的金相组织、高温性能及抗磨性进行了测试与分析,采用高温金相、透射电镜、电子探针等检测手段,查明了堆焊层的组织构造.通过微区成分分析证实骨络状组织为 Fe4(Cr,Mo)2C型复合碳化物.文中还对自行研制的 L2型高温耐磨堆焊焊条堆焊层的组织性能进行了分析,证实其性能完全满足烧络机单(双)齿辊的技术要求. 相似文献
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Christa Pohl Annekatrin Lffler Martin Schmidt Torsten Seifert 《Journal of Marine Systems》2006,60(3-4):381-395
Trace metal inventories and transboundary fluxes were estimated for the surface waters of the eastern Gotland Basin, and a mass balance for this water body was derived.The study area was delineated by a box which bordered vertically by the sea surface and the halocline and horizontally by the coast of Gotland and the coast of Latvia/Lithuania. For the calculation of the trace metal inventories in the box, a high-resolution sampling was carried out during different seasons. Additional sediment trap studies were performed to calculate the vertical particulate trace metal fluxes through the halocline.The following transboundary fluxes have been estimated: (a) atmospheric input of trace metals; (b) lateral transport from adjacent bodies of surface water; (c) diapycnal fluxes of dissolved trace metals at the halocline; (d) sinking of trace metals, associated with particles, through the halocline, (e) vertical advection through the halocline.The lateral transport into and out of the surface box is important for the metals (Cd, Cu, Zn) with “nutrient-like” behaviour. For particle reactive elements like lead, vertical sedimentation and lateral transport out of the box as much as atmospheric input and lateral input into the box are in the same order of magnitude. Turbulent diapycnal mixing plays a minor role compared to the advective fluxes.The estimated range for the residence times for the region under investigation are 0.5–1.3 years for Pb; 2–11 years for Zn, 7–36 years for Cd and 42–89 years for Cu. This demonstrates that the system reacts very fast for particle reactive elements like Pb, while for copper sedimentation processes are not the preferential sink and can be neglected. 相似文献
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张国元 《铁路通信信号工程技术》2006,3(2):31-31,60
对如何强化设备故障的追踪分析,建立和完善故障汇报、受理、原因查证以及分析、定责等安全管理制度,提出具体的要求和规定,达到减少和防止电务故障的目的。 相似文献
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本文研究了稀土元素Y、Ce对Al—Zn—Cu—Si系列低温铝基钎料的熔化温度、钎焊工艺性、电极电位及其接头的机械性能、抗腐蚀性能的影响规律,结果表明:少量Y、Ce能细化晶粒,改变组织的分布状态,它们不改变钎料的电极电位,但却提高了钎焊接头的机械性能和抗腐蚀性。 相似文献
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本实验通过益气养血保元方(OQP)对肝癌SMMC-7721细胞的作用,看到OQP可抑制肝癌细胞~3H-TdR和~(14)C-UR的掺入率,二者间有随OQP剂量增大而抑制率升高的剂量效应关系,提示OQP影响了肝癌SMMC-7721细胞的DNA、RNA合成,直接影响了癌细胞的生长分化,这些作用,可能是通过OQP中低Cu/Zn比值,高硒含量而达到的。临床证实OQP可改善中、晚期肝癌病人一般状况,恢复放疗、化疗病人白血球外,可能对肝癌细胞还有直接抑制生长分化的作用。 相似文献
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从理论和实践两个方面论述了在公路工程施工中采用金属波纹管涵,无论从施工周期、施工造价、环保意义等方面都有其不可比拟的优越性,且用金属波纹管涵进行涵洞施工,可大大提高道路行车的舒适度与安全性,避免道路中涵洞的“错台跳车”现象。 相似文献