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排序方式: 共有235条查询结果,搜索用时 31 毫秒
71.
In the upwelling area along the Namibian coast of SW-Africa sulphur discolorations were investigated to study the impact of hydrogen sulphide on the ecosystem using satellite imagery. The formation of colloidal sulphur in the upper water layer results from the oxidation of hydrogen sulphide. The occurrence of sulphur plumes as well as their temporal and spatial development was investigated in relation to the driving meteorological and oceanographic conditions. Because of the sporadic occurrence of sulphur events and the limited number of ship-borne investigations in that area remote sensing of ocean colour is the only method to follow these phenomena continuously and synoptically. In the past the sulphur plumes were studied by true colour images derived from ocean colour satellite data like sea-viewing wide field of view sensor or moderate resolution imaging spectroradiometer and identified by their typical milky turquoise discoloration. 相似文献
72.
IntroductionRemediationbynaturalattenuation (RNA)isthepreferredmethodforremediatinggroundwatercontami natedbythearomaticfuelhydrocarbons ,benzene ,toluene ,ethylbenzene ,andxylene (BTEX)etc .(Jef frey ,2 0 0 1) .ButtherearecertainconditionsunderwhichRNAisinadequate… 相似文献
73.
水对Wadsleyite和Ringwoodite电导率的影响及地球动力学意义 总被引:6,自引:0,他引:6
在Kawai-1000型多顶砧压机上,利用橄榄石相变人工合成地幔转换带矿物wadsleyite和ringwoodite,其含水量从0.03wt%到2.0wt%变化不等。在压力14~16GPa,温度873K-1273K,通过Mo:MoO2固体反应控制氧逸度的条件下,利用阻抗谱分析方法,测量获得了这些样品的电导率。实验结果显示:wadsleyite的电导率与GH^0.66呈正比,ringwoodite的电导率与GH^0.69呈正比,水极大地增强了样品的电导率;在我们的实验条件下,含水wadsleyite和ringwoodite样品的主要电荷栽体是自由质子。另外,结合大地电磁反演获得的电导率结果和我们的实验数据,我们推断中国东北地区地幔转换带中的水含量约为0.1~0.3wt%,远远高于上地幔中的水含量,这或许表明在410km处可能发生了部分熔融。 相似文献
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D. P. Zarubin 《Physics and Chemistry of Minerals》2000,27(8):590-597
Simple model calculations show that the reversible temperature effects reported for broad OH-stretching bands in infrared
spectra of silica, aluminosilicate, and similar glasses can be explained, in essentials, by homogeneous thermal broadening
of the ν(OH) envelope constituents and a decrease in intensity with increasing temperature taking place uniformly across the
band. This means that these effects are reasonably consistent with the temperature behaviour of narrow ν(OH) bands of crystalline
OH-bearing minerals. These findings leave little room for the previously agreed interpretation in terms of a change in hydrogen-bonding
strength, although the dependence of integrated intensity on temperature still remains to be understood.
Received: 16 April 1999 / Accepted: 4 April 2000 相似文献
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橄榄岩蛇纹石化过程中氢气和烷烃的形成 总被引:1,自引:1,他引:0
蛇纹石化过程中形成氢气、烷烃和有机酸,为海底热液区生命活动提供物质和能量来源,可能对地球和其他行星早期生命起源和演化有重要影响。目前关于蛇纹石化过程中氢气和烷烃形成的研究大多以橄榄石为初始物,且温度和压力较低(≤300℃,500bar)。本研究通过一系列的水热实验,研究300~500℃、1~3kbar时橄榄石、斜方辉石、单斜辉石、橄榄岩、玄武岩以及玄武岩与橄榄岩混合物发生蛇纹石化反应后氢气和烷烃的生成。300℃、3kbar时,橄榄石蛇纹石化后产生的氢气远大于辉石蚀变后产生氢气的量。随着温度的增加,400~500℃、3kbar时,橄榄石蚀变程度极低,产生氢气的量低于斜方辉石。单斜辉石实验后没有发生蚀变,不产生氢气和烷烃。400~500℃、3kbar时,橄榄岩蛇纹石化后产生的氢气和烷烃远高于橄榄石、斜方辉石和单斜辉石。玄武岩蛇纹石化后生成氢气和甲烷的量低于橄榄岩,但与玄武岩和橄榄岩混合物相当。这是因为玄武岩的单斜辉石蚀变后形成富铁的透辉石(~8.1%FeO),透辉石的Fe以Fe2+为主,这降低了Fe3+和氢气的量。以上表明,橄榄岩的蛇纹石化不同于橄榄石和斜方辉石。不仅是海底热液蚀变产生氢气和甲烷,洋壳俯冲过程中地幔楔橄榄岩蛇纹石化也会生成氢气和甲烷,但由于洋壳玄武岩的加入,氢气和甲烷的量会远小于橄榄岩蚀变时的量。 相似文献
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Previous studies of the photochemistry of small molecules in Titan’s atmosphere found it difficult to have hydrogen atoms removed at a rate sufficient to explain the observed abundance of unsaturated hydrocarbons. One qualitative explanation of the discrepancy nominated catalytic aerosol surface chemistry as an efficient sink of hydrogen atoms, although no quantitative study of this mechanism was attempted. In this paper, we quantify how haze aerosols and macromolecules may efficiently catalyze the formation of hydrogen atoms into H2. We describe the prompt reaction model for the formation of H2 on aerosol surfaces and compare this with the catalytic formation of H2 using negatively charged hydrogenated aromatic macromolecules. We conclude that the PRM is an efficient mechanism for the removal of hydrogen atoms from the atmosphere to form H2 with a peak formation rate of ∼ 70 cm−3 s−1 at 420 km. We also conclude that catalytic H2 formation via hydrogenated anionic macromolecules is viable but much less productive (a maximum of ∼ 0.1 cm−3 s−1 at 210 km) than microphysical aerosols. 相似文献