电解富集光谱法测定样品中的微量金

本文先以恒电位电解法在ｃ（Ｋｃｌ）＝０．ｌｍ０ｌ／Ｌ，ｃ（Ｈｃｌ）＝０．２ｍｏｌ／Ｌ介质液中，将微量金电解富集在特制石墨电极上，再用背景为内标的原子发射光谱法对金进行测定。本分析方法的回收率为９７．１－１０６％，变动系数为８．５５％，相对误差为－１．９６一２．２１％。操作简便快速，测定结果准确可靠     

Simultaneous determination of thermal conductivity, thermal diffusivity and specific heat in sI methane hydrate

Thermal conductivity, thermal diffusivity and specific heat of sI methane hydrate were measured as functions of temperature and pressure using a needle probe technique. The temperature dependence was measured between −20°C and 17°C at 31.5 MPa. The pressure dependence was measured between 31.5 and 102 MPa at 14.4°C. Only weak temperature and pressure dependencies were observed. Methane hydrate thermal conductivity differs from that of water by less than 10 per cent, too little to provide a sensitive measure of hydrate content in water-saturated systems. Thermal diffusivity of methane hydrate is more than twice that of water, however, and its specific heat is about half that of water. Thus, when drilling into or through hydrate-rich sediment, heat from the borehole can raise the formation temperature more than 20 per cent faster than if the formation's pore space contains only water. Thermal properties of methane hydrate should be considered in safety and economic assessments of hydrate-bearing sediment.     

Scale effect on sediment yield from sloping surfaces to basins in hilly loess region on the Loess Plateau in China

Based on data from two runoff plots and ten stations in hilly loess region Dalihe drainage basin ranging in area from 0.0006 to 3983 km² on the Loess Plateau, the relationship between mean annual specific sediment yield (Y _s) and drainage area (A) is studied, which is different from those for many other drainage areas of the world, neither at the scale of whole basin nor at local scale on the Loess Plateau. With increasing drainage area, the mean annual specific sediment yield experiences two peak values: the first peak value appears at 0.00408 km² in area corresponding to the whole slope surface, and the second peak value appears at 96.1 km² in area. The non-linear variation in the Y _s–A can be explained as follows: the first peak value can be explained by the abrupt increase in slope gradient and flow shear stress resulting in highly increased sediment concentration and specific sediment yield. And the second peak value can be explained by the combined influence of flow shear stress and drainage density, represented by dimensionless variable Ω.     

Textural and compositional controls on modern beach and dune sands,New Zealand

Textural, compositional, physical and geophysical determinations were carried out on 111 beach and dune sand samples from two areas in New Zealand: the Kapiti–Foxton coast sourced by terranes of andesite and greywackes and the Farewell Spit–Wharariki coast sourced by a wide variety of Paleozoic terranes. Our aim is to understand how long‐shore drift, beach width and source rock control the sedimentological and petrographic characteristics of beach and dune sands. Furthermore, this study shows the usefulness of specific minerals (quartz, plagioclase with magnetite inclusions, monomineralic opaque grains) to interpret the physical processes (fluvial discharges, long‐shore currents, winds) that distribute beach and dune sands in narrow and wide coastal plains. This was done by means of direct (grain size and modal analyses) and indirect (specific gravity, magnetic/non‐magnetic separations M/NM, magnetic susceptibility measurements, hysteresis loops) methods. Results are compared with beach sands from Hawaii, Oregon, the Spanish Mediterranean, Elba Island and Southern California. Compositionally, the Kapiti–Foxton sands are similar to first‐order immature sands, which retain their fluvial signature. This results from the high discharge of rivers and the narrow beaches that control the composition of the Kapiti–Foxton sands. The abundance of feldspar with magnetite inclusions controls the specific gravity of the Kapiti–Foxton sands due to their low content of opaque minerals and coarse grain size. Magnetic susceptibility of the sands is related mainly to the abundance of feldspars with Fe oxides, volcanic lithics and free‐opaque minerals. The Farewell Spit–Wharariki sands are slightly more mature than the Kapiti–Foxton sands. The composition of the Farewell Spit–Wharariki sands does not reflect accurately their provenance due to the prevalence of long‐shore drift, waves, little river input and a wide beach. Low abundance of feldspar with magnetite inclusions and free opaque grains produces poor correlations between specific gravity (Sg) and Fe oxide bearing minerals. The small correlation between opaque grains and M/NM may be related to grain size. The magnetic susceptibility of Farewell Spit–Wharariki sands is low due to the low content of grains with magnetite inclusions. Hysteresis and isothermal remnant magnetization (IRM) agree with the magnetic susceptibility values. Copyright © 2006 John Wiley & Sons, Ltd.     

Autorun analysis of sedimentary porous materials

Fundamentals of autorun analysis have been given to describe porous media geometry, including sedimantary rocks. The mathematical abstraction of porous media has been presented on the basis of random fields. Classical parameters of porous media, such as porosity and specific surface, have been expressed in terms of autorun function. Finally, a stochastic model has been proposed for the underlying generating mechanism of the porous medium. This model is capable of producing synthetic porous medium and, on the average, porosity as well as the specific surface. The first autorun coefficient is asymptotically equal to the porosity of the medium concerned. It also has been observed that the porosity together with the autorun function are sufficient to produce the specific surface value of the medium.On leave from the Technical University of Istanbul, Taksim, Turkey.     

钙质粗粒料颗粒强度和压缩特性的试验研究

目前对钙质土压缩特性的研究主要集中在钙质细砂,而实际工程中广泛存在钙质粗粒料,因此对钙质粗粒料压缩特性开展研究具有重要意义。通过颗粒强度测定仪和全自动大型固结仪对钙质土进行了单颗粒破碎试验和一维压缩试验,研究了颗粒粒径和相对密度对钙质粗粒料的颗粒强度和压缩特性的影响。单颗粒试验结果表明,钙质砂单颗粒的特征应力随着颗粒相对密度的增大而增大;单颗粒的破碎强度具有明显的尺寸效应,可利用单颗粒的特征应力进行标准化,且服从Weibull分布。压缩试验结果表明,单一粒径试样破碎后的分形维数随颗粒粒径的增大而增大;试样的Hardin破碎率与塑性功的关系为幂函数关系;在本次试验条件下,单一粒径试样的屈服应力与单颗粒的特征应力存在近似线性关系。     

Predicting the reproduction strategies of several microalgae through their genome sequences

Documenting the sex and sexual reproduction of the microalgae is very difficult, as most of the results are based on the microscopic observation that can be heavily influenced by genetic, physiological and environmental conditions. Understanding the reproduction strategy of some microalgae is required to breed them in large scale culture industry. Instead of direct observation of sex and sexual reproduction under microscope, the whole set or the majority of core meiosis genes may evidence the sex and sexual reproduction in the unicellular algae, as the meiosis is necessary for maintaining the genomic stability and the advantages of genetic recombination. So far, the available genome sequences and bioinformatic tools(in this study, homolog searching and phylogenetic analysis) allow us to propose that at least 20 core meiosis genes(among them ≥6 must be meiosis specific) are enough for an alga to maintain its sexual reproduction. According to this assumption and the genome sequences, it is possible that sexual reproduction was carried out by Micromonas pusilla and Cyanidioschyzon merolae, while asexual reproduction was adopted by Bigelowiella natans, Guillardia theta, Nannochloropsis gaditana, N. oceanica, Chlorella variablis, Phaeodactylum tricornutum and Thalassiosira pseudonana. This understanding will facilitate the breeding trials of some economic microalgae(e.g., N. gaditana, N. oceanica, C. variablis and P. tricornutum). However, the reproduction strategies of these microalgae need to be proved by further biological experiments.     

The impact of compensatory measures on public support for carbon taxation: an experimental study in Sweden

This study aims at better understanding how, and to what extent, perceptions of a policy instrument’s distributional effects impact on policy support, focusing on the case of CO₂ taxes on petrol in Sweden. Through a large-scale (N?=?5000) randomized survey experiment with a 2?×?3 factorial design, the extent to which perceptions of fairness determine attitudes to a suggested increase of the Swedish CO₂ tax is explored. Furthermore, the study considers whether these effects change with the level of the suggested tax increase, as well as whether negative sentiments can be alleviated by combining it with a compensatory measure in the shape of a simultaneous income tax cut financed by the revenues from the tax increase. The results show that a higher tax increase is both viewed as more unfair and enjoys weaker support. Furthermore, compensatory measures can be a powerful policy design tool to increase perceptions of the policy as fair, but the effect of compensation on policy support is conditioned by the individual’s left–right ideological position. Whereas people self-identifying to the right react favourably to compensatory measures, people self-identifying to the left become less supportive of a tax increase when combined with a simultaneous cut in income taxes.

Key policy insights

• Perceptions of fairness are highly important for explaining public support for climate policy tools, specifically CO₂ taxes.

• Compensatory measures can be a powerful policy design tool to increase perceptions of the policy as less unfair.

• However, the effect of compensatory measures on policy support is conditioned by ideological position, and only successful among people to the ideological right.

• In contexts dominated by right-wing ideals, a combination of a tax and a compensatory scheme may be a successful route forward towards increased climate policy support.

• In left-oriented contexts the results imply that a CO₂ tax without compensation seems more likely to increase support.

     

北京平原区第四系热物性参数特征及对浅层地热能开采的影响因素分析

【研究目的】 岩土热物性是影响浅层地热能资源评价及利用的重要参数。【研究方法】 在北京平原区各冲洪积扇采集了695件第四系岩土样品进行热物性及土工参数测试,分析了热物性参数特征及其对浅层地热能开采的影响。【研究结果】 北京平原区第四系岩土热导率平均值为1.465~2.022 W/(m·K),热扩散率平均值为0.450×10^-6~0.841×10^-6 m²/s,比热容平均值为2.323~3.080 MJ/(m³·K),热导率（λ）与热扩散率（κ）值存在一定的线性关系,相关方程为λ =1.6973κ + 0.6127。第四纪松散沉积物颗粒越细,热导率值越低;含水率0~5%范围内,热导率随含水率增加迅速增大,含水率5%~20%范围内,热导率增加变缓并趋于稳定,含水率20%~40%范围内,热导率随含水量增大而降低;在天然状态下,热导率随着密度的增加而增大,随着孔隙比的增加而降低;样品温度在0~40 ℃范围内,热导率随温度升高呈先减小后增大的趋势,20 ℃时热导率最低。【结论】 第四系热物性参数随地质条件变化而变化,热物性参数大小会影响浅层地热能储存、采集和扩散能力,热导率、热扩散率及比热容越大,岩土蓄热和导热能力越强。     

页岩气储层粘土矿物孔隙特征及其甲烷吸附作用

粘土矿物是页岩的主要组成矿物,与页岩气的赋存和富集密切相关。粘土矿物因其特殊的晶体结构,在晶层之间、矿物内部以及矿物颗粒之间形成了不同类型的孔隙,这些孔隙的大小、形貌和比表面积决定着粘土矿物的甲烷吸附能力。为此,本文综述了粘土矿物的孔隙结构以及孔隙中的水和有机质对甲烷吸附性的影响,指出不同类型的粘土矿物孔隙发育与形貌特征存在差异,蒙脱石中多发育圆形、狭缝状的微孔且总比表面积最大,导致蒙脱石在所有粘土矿物中的甲烷吸附量最大;伊利石与高岭石中多发育中孔与大孔,吸附甲烷的能力低于蒙脱石。粘土矿物孔隙中的水与有机质显著影响到甲烷的吸附能力,水分子会占据孔隙表面,降低了甲烷的吸附能力,但可溶有机质对粘土矿物甲烷吸附能力的具体影响目前尚不明了。同时,根据页岩气勘探需求指出了本方向某些有待深入探讨的问题。