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1.
Lars Olov Andersson 《Physics and Chemistry of Minerals》2008,35(9):505-520
The EPR spectra of Maxixe-type beryl contain a large number of overlapping signals. The angular dependence of the 1:3:3:1
signal typical for the CH3 radical shows that this radical is located at the center of the channel cavity with its symmetry axis parallel to the crystal
c-axis and is rotating around this axis. Its EPR spectrum is axially symmetric with g
// = 2.00263, g
⊥ = 2.00249 and A// = 2.288 mT, A⊥ = 2.256 mT. These anisotropies have the opposite signs of those found for surface-adsorbed methyl radicals. Hydrogen atoms
are located at position 2a at the center of the beryl cavity and the EPR parameters of the narrow doublet signal are A
0 = 1,407 MHz and g = 2.00230. Another doublet signal, which is broader and has axial symmetry with g
// = 2.00265, g
⊥ = 2.00625 and A// = 0.895 mT, A⊥ = 0.885 mT, could come from a HCO3 radical. One narrow and easily saturated signal with g
// = 2.00227 and g
⊥ = 2.00386 is interpreted to arise from a carbon monoxide radical in the beryl channel, oriented with its axis parallel to
the crystal c-axis. Additional weak doublet lines, which have similar g values as the carbon monoxide radical, are created by nearby hydrogens. A powder spectrum with g
// = 2.0017 and g
⊥ = 2.0004 appears upon UV irradiation of the single crystal and is easily saturated. This spectrum is interpreted to arise
from a carbon dioxide radical, which rotates around its symmetry axis. 相似文献
2.
Eric A. Betterton 《Journal of Atmospheric Chemistry》1993,17(4):307-324
An experimental study is described of Fe(III)-S(IV) formation constants measured as a function of pH (1–3), ionic strength (0.2–0.5 M) and [Fe(III)]
T
(2.5–5.0×10–4 M) using a continuous-flow spectrophotometric technique to make observations 160 ms after mixing. Preliminary experiments using pulse-accelerated-flow (PAF) spectrophotometry to measure rate constants on a microsecond timescale are also described. The conditional formation constant at 25 °C can be modeled with the following equation: {ie307-1} where {ie307-2}K
7 andK
8 can be interpreted as intrinsic constants for the coordination of HSO
3
–
by FeOH2+ and Fe3+, respectively, but until further evidence is obtained they should be regarded as fitting constants. PAF spectrophotometry showed that the initial reaction of Fe(III) with S(IV) (pH 2.0) is characterized by a second-order rate constant of 4×106 M–1 s–1 which is comparable to rate of reaction of FeOH2+ with SO
4
2–
. However, the PAF results should be regarded as preliminary since unexpected features in the initial data indicate that the reaction may be more complex than expected. 相似文献
3.
Daily zenith scattered light intensity observations were carried out in the morning twilight hours using home-made UV-visible
spectrometer over the tropical station Pune (18‡31′, 73‡51′) for the years 2000–2003. These observations are obtained in the
spectral range 462–498 nm for the solar zenith angles (SZAs) varying from 87‡ to 91.5‡. An algorithm has been developed to
retrieve vertical profiles of ozone (O3) and nitrogen dioxide (NO2) from ground-based measurements using the Chahine iteration method. This retrieval method has been checked using measured
and recalculated slant column densities (SCDs) and they are found to be well matching. O3 and NO2 vertical profiles have been retrieved using a set of their air mass factors (AMFs) and SCDs measured over a range of 87–91.5‡
SZA during the morning. The vertical profiles obtained by this method are compared with Umkehr profiles and ozonesondes and
they are found to be in good agreement. The bulk of the column density is found near layer 20–25 km. Daily total column densities
(TCDs) of O3 and NO2 along with their stratospheric and tropospheric counterparts are derived using their vertical profiles for the period 2000–2003.
The total column, stratospheric column and tropospheric column amounts of both trace gases are found to be maximum in summer
and minimum in the winter season. Increasing trend is found in column density of NO2 in stratospheric, tropospheric and surface layers, but no trend is observed in O3 columns for above layers during the period 2000–2003 相似文献
4.
A. Heusel-Waltrop K. Diehl S. K. Mitra H. R. Pruppacher 《Journal of Atmospheric Chemistry》2003,44(2):211-223
Laboratory experiments have been carried out to investigate the uptake of sulfur dioxide by water drops containing heavy metal ions where the metal ions serve as catalysts to oxidise the taken up S(IV) into S(VI). During the gas uptake the drops were freely suspended at their terminal velocity in the airstream of the Mainz vertical wind tunnel. Two series of experiments were carried out, one with large millimeter size water drops containing manganese or iron ions, and the other with small water drops containing manganese ions and having radii in hundreds of micron size range. The experimental results were compared against model computations using the Kronig–Brink model and the fully mixed model, modified for the case that heavy metal ions present in the liquid phase act as catalysts for the oxidising process. The results of the model calculations show that there are only small differences between the predicted gas uptake according to the two models. In addition it was found that the experimental obtained results from the uptake of SO2 by water drops containing heavy metal ions for both, large and small water drops did agree with the model results. 相似文献
5.
Steven B. Brooks Timothy L. Crawford Walter C. Oechel 《Journal of Atmospheric Chemistry》1997,27(2):197-207
Large carbon dioxide plumes with concentrations up to 45 ppm aboveambient levels were measured about 15 km downwind of the Prudhoe Bay, Alaskamajor oil production facilities, located at 70° N Lat. above the ArcticCircle. The measured emissions were 1.3 × 103 metrictons (C) hour-1 (11.4× 106 metric tons(C) year-1), six times greater than the combustion emissionsassumed by Jaffe and coworkers in J. Atmos. Chem. 20 (1995), 213–227,based on 1989 reported Prudhoe Bay oil facility fuel consumption data, andfour times greater than the total C emissions reported by the oil facilitiesfor the same months as the measurement time periods. Variations in theemissions were estimated by extrapolating the observed emissions at a singlealtitude for all tundra research transect flights conducted downwind of theoil fields. These 30 flights yielded an average emission rate of1.02 × 103 metric tons (C) hour-1 with astandard deviation of 0.33 × 103. These quantity ofemissions are roughly equivalent to the carbon dioxide emissions of7–10 million hectares of arctic tussock tundra (Oechel and Vourlitis,Trends in Ecol. Evolution 9 (1994), 324–329). 相似文献
6.
Simultaneous in situ immobilisation of uranium (U) and radium (226Ra) by injectible amounts of grey cast iron (gcFe), nano-scale iron (naFe) and a gcFe/MnO2 mixture (1:1) was studied in batch and column tests. Both 0.5 g/L naFe and gcFe are effective in 226Ra and U removal from mine water, whereas MnO2 addition clearly increased the efficiency of gcFe for 226Ra and U immobilisation. In a column test with 0.6 wt% gcFe/MnO2 mixture (1:1), neither 226Ra nor U was detected in the effluent after replacement of 45 pore volumes. A sequential extraction under flow condition revealed 226Ra to be mostly occluded in manganese oxides. Uranium was mostly sorbed onto poorly crystalline iron hydroxides, but a significant part was found to be occluded in manganese oxides also. The results of this study suggest that MnO2 promotes iron hydroxide formation under slightly reducing environmental conditions resulting in an increased pollutant retention capacity. 相似文献
7.
以二氧化氯作为一种新型的消毒剂和杀菌剂 ,以传统含氯制剂 (如漂白粉、二氯异氰尿酸钠、三氯异氰尿酸 )作为对照 ,比较其在治疗欧洲鳗细菌性疾病及改善养殖水质方面的显著特性 ,其作用活性与环境 (如 p H、温度、氨及有机物 )因子的关系。结果表明 ,二氧化氯 (Cl O2 )对爱德华氏菌、嗜水气单胞菌和柱状屈挠杆菌有很好的杀灭效果 ,能迅速治愈欧洲鳗的赤鳍病和肝肾病 ,且能有效改善养殖水体 ,水中生化需氧量比对照组下降 10 %~ 30 % ,化学耗氧量下降 5% ,溶氧量提高 8%~ 10 %。当二氧化氯体积分数为 8m L/m3时 ,其杀菌率均高达 90 %以上 ,为氯制剂的 1.8倍 ,且活性不受环境因子的影响 相似文献
8.
Supercritical Carbon Dioxide Extraction of Organic Matter from Petroleum Source Rocks and Its Implications 总被引:2,自引:0,他引:2
Organic matter was experimentally extracted by supercritical fluids(CO2 1% isopropanol)from petroleum source rocks of different thermo-maturities at different buried depths in the same stratigraphic unit in the Dongying Basin.The results show that supercritical fluid extraction(SFE)is more effective than Soxhlet extraction(SE),with higher amounts and greater varieties of hydrocarbons and soluble organic matter becoming extractive.The supercritical CO2 extraction is therefore considered more valuable in evaluation of petroleum source rocks and oil resources,particularly those of immature types. 相似文献
9.
张二勇 《水文地质工程地质》2012,39(2):131-138
澳大利亚Otway盆地二氧化碳地质封存示范工程是澳大利亚第一个完整的从源到汇的碳封存研究项目,也是碳封存领导论坛(CSLF)和国际能源总署(IEA)认可的二氧化碳地质封存国际合作项目,由澳大利亚CO2CRC牵头开展相关研究。项目封存场地位于澳大利亚维多利亚州的Otway盆地,分两个阶段进行。第一阶段,2004~2010年开展衰竭气田的二氧化碳地质封存研究,已向位于地下深处2000m的晚白垩系Waarre C粗砂岩地层灌注二氧化碳混合气体65000多吨,并成功实现构造圈闭封存,同时开展了地下水、土壤气体、大气、地球化学、地球物理等综合监测;第二阶段,2010 ~2015年开展地下咸水层封存二氧化碳的研究,将向位于地下1500m深处的晚白垩系Paaratte细砂岩咸水含水层注入10000t二氧化碳,实现二氧化碳毛细滞留圈闭封存,目前正在开展前期抽注试验。 相似文献
10.
由于海冰覆盖,北极碳汇(Arctic Carbon Sink)在全球碳通量预算中经常被忽略或简单处理。但随着全球变化加剧,北极发生快速变化,北极碳循环及其对全球变化的响应与反馈日趋重要。综合对北极碳汇的研究结果,分析了北极碳汇的来源、变化以及主要调控因子,评估了北极碳汇现状。探讨了在全球变化中,影响北极碳汇变化的因素及其对未来北极碳汇变化趋势的影响。
相似文献