Safety-related conclusions for the application of ultrasound in explosive atmospheres

International safety regulations such as EN 1127-1 consider ultrasound to be an ignition source. Currently, applications of ultrasound in explosive atmospheres have to comply with a threshold value of 1 mW/mm². However, it is unclear as to how this intensity has to be measured and, therefore, this threshold value is poorly defined. Moreover, it is based on theoretical estimations in analogy to other ignition sources and there are no publications or significant records on these estimations. Within a research project at PTB, it has now been investigated experimentally in relation to worst-case considerations including airborne ultrasound, focused MHz ultrasound in liquids and acoustic cavitation. On the basis of the results of the research it is now possible to revise the current regulations and to specify measures for safe operation of ultrasonic applications in explosive atmospheres. In this context, for ultrasound coupled directly to gaseous atmospheres a new threshold value of 170 dB (re. 20 μPa) can be suggested, and for ultrasonic applications in liquids, an augmentation can be made to the threshold to 400 mW/mm².     

Ionic imbalance due to hydrogen carbonate from Asian dust

In an attempt to identify the ionic imbalance, hydrogen carbonate, HCO₃⁻ (bicarbonate), was determined together with the commonly determined nine major ions because the imbalance was frequently encountered in the chemical analysis of samples with high pHs. Titration method was applied for the determination of the samples with pH higher than 5.6. These samples amounted to 102 of the 1536 samples collected in Hokkaido, Northern Japan, from April 1998 to December 2002. Of the 102 samples, 74 (Group A) showed an acceptable ion balance without including HCO₃⁻. In the other 28 (Group B), however, inclusion of HCO₃⁻ successfully improved the ion balance. These results suggested that hydrogen carbonate was a potential candidate for explaining the imbalance. The hydrogen carbonate concentrations showed a strong correlation with the corresponding non-sea salt calcium (nss-Ca²⁺) concentrations, which implied that hydrogen carbonate was derived from calcium carbonate particles incorporated into falling raindrops or cloud droplets. For Group A, the relationship between hydrogen carbonate and the nss-calcium ion concentration was very similar to that for commonly suspended particles in Hokkaido. On the other hand, Group B exhibited a stronger but significantly different correlation. To the samples of Group B, a back-trajectory analysis was applied to demonstrate that the samples were associated with aerosol travelling from Northern China or Mongolia, which indicated that alkaline aerosol affected the chemistry. In consideration of these findings, the current standard of the ion balance should be critically reviewed for modification in regard to the contribution of hydrogen carbonate not only in source areas but also in receptor areas of alkaline aerosol.     

中国原油进口来源国供应安全的定量评估

原油供给安全在中国国家安全中占有重要地位,对其定量评估可为防范风险提供政策参考。采用事件数据分析法定量测度中国与21个主要原油进口来源国之间的双边关系,结果表明：中国与大多数原油贸易伙伴的关系处于中低水平,但近十多年总体保持上升趋势,原油进口存在一定的政治关系风险但趋于下降。选用资源、政治、经济、运输、军事5个方面的11个指标,通过组合赋权法确定指标权重,运用集对分析方法评估中国21个原油进口来源国的供应安全度,并识别主要障碍因子。结果表明：21国供应安全度存在较大差异。部分中东国家、俄罗斯、委内瑞拉、哈萨克斯坦供应安全度较高,多数非洲国家和亚太国家供应安全度较低。供应国的原油资源状况、运输风险、政治风险是制约多数国家供应安全的主要障碍因素。为防范风险,中国需坚持开展多边“能源外交”,扩大战略石油储备等多方面施策方针。     

Advanced molecular-fingerprinting analysis of dissolved organic sulfur by electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry using optimal spray solvent

Molecular level characterization of dissolved organic sulfur (DOS) by electrospray ionization-Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR MS) is necessary for further understanding of the role of DOS in the environment. Here, ESI spray solvent, a key parameter for ion production during ESI process, was investigated for its effect on the molecular characterization of DOS by ESI-FTICR MS. 100% MeOH as spray solvent was found for the first time to remarkably enhance the ionization efficiency of the majority of CHOS-molecules in NOM, which facilitated a total of 1473 CHOS-molecular formulas with one sulfur atom to be detected. The number of CHOS-molecular formulas obtained using 100%MeOH as spray solvent increased notably over 740 in comparison with those using 50% MeOH aqueous solution (731) or 50% ACN aqueous solution (653). Moreover, due to the enhancement of ionization efficiency of DOS during ESI processes, the tandem mass spectra of the NOM CHOS-molecules could be easily obtained using 100% MeOH as spray solvent, which were hardly obtained using 50% MeOH aqueous solution as spray solvent. The results of the tandem mass spectra suggested the first discovery of organosulfates or sulfonic acids in Suwannee River NOM sample. A simple method based on 100% MeOH as ESI spray solvent for advanced molecular characterization of DOS by ESI-FTICR MS was proposed and applied, and the results revealed more molecular information of DOS in sea DOM samples.     

大气沉降向华中丘陵区稻田输入硫通量的观测

选取我国华中丘陵区的湖南省长沙县一个典型水稻种植区,对2015与2016年2年雨水样中的SO₄²-S和大气SO₂的沉降量进行监测,分析雨水中SO₄^2-、NO₃^-的关系,解析大气硫沉降的主要来源.结果表明,研究区大气中SO₂-S和雨水中SO₄^2--S的年均浓度分别为8.5 μg/m³和1.1mg/L,大气硫沉降年均总量为26.8kgS/（hm²·a）,其中年均降雨混合沉降量18.2kgS/（hm²·a）,年均干沉降量为8.6kgS/（hm²·a）.研究区域硫素干、混合沉降量存在明显的季节差异,硫素混合沉降春季高于夏、秋、冬季,而硫素干沉降冬季高于春、夏、秋季.雨水中NO₃^-/SO₄^2-的质量比大多小于1,表明研究区大气硫素主要来自固定污染源（燃煤）.华中丘陵区稻田具有较高的硫沉降,但硫沉降量已较21世纪初出现了较大幅度下降,农业生产中需要根据农田硫素收支状况酌情补充硫肥来保证作物高产稳产.     

东海表层沉积物中多环芳烃的分布特征及来源解析

本研究对东海沉积物中多环芳烃(PAHs)组成及含量进行了分析,发现多环芳烃总浓度为8.2~180.2 ng/g,和国内外其它区域相比,整体处于一个低至中等程度的污染水平。东海沉积物中PAHs的分布整体表现为中间低、两端高的格局。内陆架是长江入海物质的主要沉积区,也是PAHs的主要汇集区;陆架北部区域的物质来源复杂,但总体受长江入海泥沙的控制,自西向东PAHs含量梯度递减;研究区域的东北部,较高的PAHs可能源于济州岛的输入;冲绳海槽也含有较高PAHs;而残留沉积区中PAHs含量极低。通过多环芳烃组成特征判断,东海表层沉积物中PAHs主要来自煤、木材、油类的燃烧,还有部分来自油类的泄漏。同时不同区域Ba P/Be P、Ba A/Chry比值的差别表明内陆架及冲绳海槽的PAHs主要来自河流输送,残留沉积区的PAHs可能主要来自大气沉降。     

WK－1A型二氧化硫自动测定仪测定烟气中SO_2的方法研究

本文研究了仪器电导法测定烟气中ＳＯ２的监测方法，并与碘量法进行了比较，提出了吸收液测定的影响及吸收液的配制方法。本方法简单快速，能够满足烟气中ＳＯ２监测工作的要求。     

膜、柱串联固相萃取-高效液相色谱法测定水中多环芳烃(PAHs)的研究

建立了用膜-柱串联固相萃取(SPE)技术,甲醇和水作为流动相进行梯度洗脱,紫外和荧光检测器串联的高效液相色谱法(HPLC)分析水中EPA优先监控的16种PAHs的方法.     

The Chemistry of Soils, Rocks and Plant Bioindicators in Three Ecosystems of the Holy Cross Mountains, Poland

In June of 2000, biogeochemical study was carried out in three ecosystems of the Holy Cross Mountains (south-central Poland). This paper presents element concentrations and stable sulfur (and in one site lead) isotope ratios in rocks, detailed soil profiles, and plant bioindicators including epiphytic lichen Hypogymnia physodes (L.) Nyl., mosses (Pleurozium schreberi (Brid.) Mitt., Hypnum cupressiforme Hedw. S. Str., Hylocomium splendens (Hedw.) B.S.G.), Scots pine (Pinus sylvestris L.), common birch (Betula pendula Roth.), aspen (Populus tremula L.) and English oak (Quercus robur L.). Chemical analyses were performed with ICP-AES and AAS methods in the accredited laboratory (Central Chemical Laboratory of the Polish Geological Institute in Warsaw). The principal objective of this study was to compare the chemical composition of rocks, soils and selected plant bioindicators between investigation sites using the same methods of sample collection, preparation and analyses. The results of this study have shown that there is a high variability in concentrations of elements in plant bioindicators from the same sites that can not be explained only by soil properties or anthropogenic influence. This conclusion indicates that for biomonitoring purposes (especially with vascular plants) we cannot neglect individual features of the species examined.     

冷凝吸附法测定痕量挥发性含硫气体

采用冷凝吸附法对痕量挥发性含硫气体的测定进行了研究 ,结果表明自行设计的冷凝吸附装置对于痕量挥发性含硫气体的富集有着良好的效果 ,富集效率可达 94%以上