On the reactive uptake of gaseous PAH molecules by micron-sized atmospheric water droplets

A falling droplet reactor was used to study the heterogeneous oxidation of gaseous PAH molecules adsorbed on a 92 μm diameter water droplet by ozone. The dynamic partition constant for the PAH between the droplet and air and the first-order surface rate constant was measured. The increase in uptake with ozone concentration was due to increased mass transfer via surface reaction of co-adsorbed ozone and PAH. The surface rate constant was rationalized through the Langmuir–Hinshelwood mechanism. The rate constant was smaller for phenanthrene than naphthalene. The main reaction products identified in the aqueous phase indicated the peroxidic route for surface reaction of ozone with PAH. The heterogeneous reaction rate of ozone with adsorbed phenanthrene at the air–water interface of a 92-μm droplet was estimated to be 9300 times larger than the homogeneous reaction of ozone with phenanthrene in the gas phase and it was 76 times larger than the homogeneous oxidation by hydroxyl radical in the gas phase. For naphthalene that is more volatile, however, the homogeneous reaction with hydroxyl was more important. Increased organic carbon added to the droplet increased both the partition constant for phenanthrene and surface reaction with ozone. The partition constant for a droplet formed from actual fog water was much larger than for pure distilled water.     

Deep melting and sodic metasomatism underneath the highly oblique-spreading Lena Trough (Arctic Ocean)

Abyssal peridotites collected along the highly oblique-spreading Lena Trough north of Greenland and Spitsbergen have mineral compositions that are similar to residual abyssal peridotites, except for high sodium concentrations in clinopyroxene (cpx). Most samples are lherzolites with light rare earth element (REE)-depleted cpx trace element patterns, but significantly fractionated middle to heavy REE ratios at relatively high heavy REE concentrations. Such characteristics can only be explained by initial melting of a garnet peridotite followed by low degrees of melting in the stability field of spinel peridotite. The residual garnet signature requires either a high potential temperature of the upwelling mantle, or elevated solidus-lowering water contents. The limited spinel field melting suggests a deep cessation of melt extraction, possibly because of the presence of a thick lithospheric cap. This is consistent with the extremely low effective spreading rate and the vicinity to a passive continental margin, which allow conductive cooling to reach deeper levels than commonly estimated for faster mid-ocean ridges. High sodium concentrations in cpx are neither explainable by melt refertilization, nor by a simple diffusion mechanism. The efficient fractionation of sodium from the light REE requires post-melting metasomatism, which is typically restricted to the subcontinental lithosphere. This might imply that the Lena Trough peridotites represent unroofed subcontinental mantle, from which no melt was extracted during the opening of the Lena Trough. It is more likely that sodic metasomatism occurred after partial melting underneath the Lena Trough, and that such an enrichment process is responsible for elevated sodium concentrations in abyssal peridotites elsewhere. Sodium in cpx of residual peridotites can therefore not serve as an indicator of partial melting or melt refertilization.     

Aqueous volatiles in hydrothermal fluids from the Main Endeavour Field, northern Juan de Fuca Ridge: temporal variability following earthquake activity

The Main Endeavour Field, northern Juan de Fuca Ridge, experienced intense seismic activity in June 1999. Hydrothermal vent fluids were collected from sulfide structures in September 1999 and July 2000 and analyzed for the abundance of H₂, H₂S, CH₄, CO₂, NH₃, Mg and Cl to document temporal and spatial changes following the earthquakes. Dissolved concentrations of CO₂, H₂, and H₂S increased dramatically in the September 1999 samples relative to pre-earthquake abundances, and subsequently decreased during the following year. In contrast, dissolved NH₃ and CH₄ concentrations in 1999 and 2000 were similar to or less than pre-earthquake values. Aqueous Cl abundances showed large decreases immediately following the earthquakes followed by increases to near pre-earthquake values. The abundances of volatile species at the Main Endeavour Field were characterized by strong inverse correlations with chlorinity. Phase separation can account for 20-50% enrichments of CO₂, CH₄, and NH₃ in low-chlorinity fluids, while temperature- and pressure-dependent fluid-mineral equilibria at near-critical conditions are responsible for order of magnitude greater enrichments in dissolved H₂S and H₂. The systematic variation of dissolved gas concentrations with chlorinity likely reflects mixing of a low-chlorinity volatile-enriched vapor generated by supercritical phase separation with a cooler gas-poor hydrothermal fluid of seawater chlorinity. Decreased abundances of sediment-derived NH₃ and CH₄ in 1999 indicate an earthquake-induced change in subsurface hydrology. Elevated CO₂ abundances in vent fluids collected in September 1999 provide evidence that supports a magmatic origin for the earthquakes. Temperature-salinity relationships are consistent with intrusion of a shallow dike and suggest that the earthquakes were associated with movement of magma beneath the ridge crest. These data demonstrate the large and rapid response of chemical fluxes at mid-ocean ridges to magmatic activity and associated changes in subsurface temperature and pressure.     

碳酸钾焙烧分解富钾页岩的实验研究

通过实验探讨了富钾页岩 碳酸钾体系热分解反应过程。以富钾页岩分解率为目标函数，正交实验表明：最佳焙烧温度为820-830℃，富钾页岩：碳酸钾(质量比)=1．00：1．51，最佳焙烧时间60min，生料粒度60～80目。并用热重／差热分析和X粉晶衍射进行分析，拟合热力学数据，初步分析了反应机理。     

Polyatomic Interferences Produced by Macroelements During Direct Multi-Elemental ICP-MS Hydrochemical Analysis

An experimental study of the interferences produced by macroelements (Na, K, Ca, Mg, Sr, S, Cl, Si, N and C) contained in natural waters during inductively coupled plasma-mass spectrometry (ICP-MS) is presented. The most significant interferences created by these elements were found to be SO, CO, CAr, SiH, SiO, NaH, NaAr, MgAr, CaO, KO and KAr, the magnitude of which was dependant on the concentration of each macroelement. To reduce these interferences, different approaches, for example, desolvating nebulisation, high resolution and dynamic reaction cell ICP-MS were applied and compared. All three approaches were found to be useful tools for significantly reducing various polyatomic interferences. Advantages and disadvantages for each approach are discussed.     

Deformation, mass transfer and mineral reactions in an eclogite facies shear zone in a polymetamorphic metapelite (Monte Rosa nappe, western Alps)

This study analyses the mineralogical and chemical transformations associated with an Alpine shear zone in polymetamorphic metapelites from the Monte Rosa nappe in the upper Val Loranco (N‐Italy). In the shear zone, the pre‐Alpine assemblage plagioclase + biotite + kyanite is replaced by the assemblage garnet + phengite + paragonite at eclogite facies conditions of about 650 °C at 12.5 kbar. Outside the shear zone, only minute progress of the same metamorphic reaction was attained during the Alpine metamorphic overprint and the pre‐Alpine mineral assemblage is largely preserved. Textures of incomplete reaction, such as garnet rims at former grain contacts between pre‐existing plagioclase and biotite, are preserved in the country rocks of the shear zone. Reaction textures and phase relations indicate that the Alpine metamorphic overprint occurred under largely anhydrous conditions in low strain domains. In contrast, the mineralogical changes and phase equilibrium diagrams indicate water saturation within the Alpine shear zones. Shear zone formation occurred at approximately constant volume but was associated with substantial gains in silica and losses in aluminium and potassium. Changes in mineral modes associated with chemical alteration and progressive deformation indicate that plagioclase, biotite and kyanite were not only consumed in the course of the garnet‐and phengite‐producing reactions, but were also dissolved ‘congruently’ during shear zone formation. A large fraction of the silica liberated by plagioclase, biotite and kyanite dissolution was immediately re‐precipitated to form quartz, but the dissolved aluminium‐ and potassium‐bearing species appear to have been stable in solution and were removed via the pore fluid. The reaction causes the localization of deformation by producing fine‐grained white mica, which forms a mechanically weak aggregate.     

桩基静载试验之钢铰线锚杆横梁反力装置测试技术的研究与应用

依据《建筑桩基技术规范》[1](JGJ94-94)和美国《桩基轴向抗压静载标准试验方法》[2](ASTMD1143),探讨了桩基静载试验之钢铰线锚杆横梁反力装置的测试技术,并成功的解决了某外资工地桩基静载试验的技术难题。     

氧化酸性铬蓝K褪色光度法测定钒

在１８０～２５０ｍｏｌ／ＬＨ２ＳＯ４介质中,Ｖ（Ⅴ）对酸性铬蓝Ｋ有褪色作用。褪色程度与Ｖ（Ⅴ）量相关,借此建立了吸光光度测定Ｖ的方法。实验表明,褪色反应随温度升高而加快,在沸水浴中１０ｍｉｎΔＡ可达最大值,流水冷却后吸光度保持２４ｈ不变,有色溶液的最大吸收波长为５２０ｎｍ,ε＝１０×１０４Ｌ·ｍｏｌ－１·ｃｍ－１,Ｖ（Ⅴ）量在０～３２ｍｇ／Ｌ内与有色溶液吸光度的减少值呈线性关系。所拟方法用于测定铁矿石中微量Ｖ时,结果与苯甲酰基苯胲比色法一致。     

熔体─上地幔岩石的相互作用及稀土元素模拟计算──以法国中央高原堡雷(Bore)幔源包体为例

产于法国中央高原堡雷（Boree）的具镶嵌结构方辉橄榄岩包体被认为是大陆活动区碱性玄武岩捕获的、来源最深的尖晶石相上地幔样品。已有的岩浆堆积说和等物理化学环境中重结晶模式难于解释其矿物学、微量元素和Sr－Nd同位素地球化学特征,为此我们提出了热柱来源熔体渗滤岩石圈底部的新成因模式。渗滤熔体和岩石圈地幔之间的反应不仅导致了矿物含量的变化,而且形成了特征的微量元素配分型式和同位素组成。REE模拟计算表明,熔体／岩石比值的大小、熔体性质以及熔体-岩石反应机制的多样性是控制本区幔源包体地球化学及其岩石变形、结晶程度之间相关性的重要因素。     

广东长坑金银矿床成矿机制热力学模拟研究

长坑金银矿床为沉积岩中的微细浸染型金矿与交代型银矿构成的矿床组合,金、银矿化与碳酸盐和碎屑岩围岩的硅化蚀变关系密切并呈分带现象,矿石类型主要为含矿硅化岩。矿化温度主要在300～170 C之间,成矿流体的主要成分为K~-、Na~-、Ca~(2+)、Mg~(2+)、Cl~(-)。金属配合物的分配计算显示,金在成矿热液中主要以疏氢配合物迁移,而银、铁、铅、锌则以氯配合物为主,铁、铅、锌在成矿后期的中性-弱碱性环境下可转变为羟基和硫氢配合物。热液-碳酸盐岩反应模拟证实水-岩相互作用是银矿石形成的有效机制。矿物组合的溶解度分析表明,金、银矿物分别在早期弱酸性和后期中-碱性条件下沉淀富集,这是造成金、银矿体分离和分带的主要或有利因素。