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121.
Calcium and magnesium‐bearing sabugalite occurs as aggregations of yellowish platy crystals in veinlets or druses in conglomerate from the oxidized parts of the Tono uranium deposit, Central Japan. X‐ray powder diffractometry of this mineral has reflections consistent with previous powder diffraction data of sabugalite. It is included in the monoclinic system with space group C2/m and calculated cell parameters of a = 19.68Å, b = 9.89Å, c = 9.82Å α = γ = 90°, β‐96.93° and V = 1897.83Å3. Chemical analysis yields a formula of (Ca0.10 Mg0.09)Σ0.19Al0.53(UO2)2.04((PO4)1.99(AsO4)0.01)Σ2.00·11.22H2O. EMPA mapping shows that the mineral is compositionally uniform with no micron‐scale layering. Charge of cations including Ca and Mg in the cation‐H2O layer is 1.98 being identical to that of autunite group minerals. This suggests that the charge balance in the cation‐H2O layer of the mineral could be made by the alkaline earth or alkaline elements rather than by hydrogen ions. 相似文献
122.
Effect of cropland occupation and supplement on light-temperature potential productivity in China from 2000 to 2008 总被引:2,自引:0,他引:2
There are more people but less land in China,so food safety has always been a most important issue government concerned.With continuous population increase,economic development and environment protection,cropland occupation and supplement are unavoidable.It not only leads to the variation of cropland area,but also makes the light-temperature potential productivity per unit area different due to regional climate differentiation,therefore impacts the total potential productivity and food output eventually.So,it is necessary to analyze the climate differentiation between occupation and supplement cropland areas and to study its impact on total potential productivity,which is significant to reasonably develop natural resources and instruct agricultural arrangement.This study firstly discussed the variation and distribution of occupation and supplement croplands in China from 2000 to 2008,then analyzed the climate differentiation between occupation and supplement cropland areas and its effect on light-temperature potential productivity.The results demonstrate:1) From 2000 to 2008,the cropland variation presented occupation in the south and supplement in the north,but overall decreased.Supplement cropland was mainly from ecological reclamation(77.78%) and was mainly distributed in Northeast China and Northwest China with poor climatic and natural conditions.Occupation cropland was mainly used for construction(52.88%) and ecological restoration(44.78%) purposes,and was mainly distributed in the Huang-Huai-Hai Plain,and the middle and lower reaches of the Changjiang(Yangtze) River with better climatic and natural conditions.2) The climate conditions were quite different in supplement and occupation cropland areas.The annual precipitation,annual accumulated temperature and average annual temperature were lower in the supplement cropland area,and its average po-tential productivity per unit was only 62% of occupation cropland area,which was the main reason for the decrease of total potential productivity.3) Cropland occupation and supplement led to the variation of total potential productivity and its spatial distribution.The productivity decreased in the south and increased in the north,but had a net loss of 4.38315×107 t in the whole country.The increase of cropland area was at the cost of reclaiming natural forest and grassland resources,and destroying natural ecological environment,while the decrease of cropland area was mainly due to a lot of cropland occupied by urban-rural construction,which threatened the sustainable use of cropland resources. 相似文献
123.
地壳风化速率研究综述 总被引:7,自引:1,他引:6
地壳风化速率研究的理论基础是质量守恒原理和溶液与矿物反应动力学法则。元素在风化过程中的行为受多种因素控制,主要包括基岩风化量、大气沉降量、径流量、生物的输出数量和人为输入量(如施肥)。硅酸盐矿物化学风化过程中,矿物与溶液之间总的化学反应速率是单个反应速率之和,其中涉及到 3个关键参数,即:酸中和能力(ANC)、基本阳离子/无机铝(BC/Al无机)比值和临界负荷(CL)。风化速率的研究主要采用四种方法,即PROFILE模型、基本阳离子损耗、元素输入-输出指数和Sr同位素比值等。PROFILE模型是一个稳定态的综合土壤化学模型,矿物的分解速率、矿物的暴露表面积、土壤水饱和度和土壤层厚度决定着该矿物的风化速率,总的风化速率为各种矿物的风化速率之和。元素损耗,主要是基本阳离子(Ca、Na、K和Mg)的损耗,假设Ti、 Zr和Nb在成土过程中含量稳定并不参与风化反应,那么对于给定的土壤层,化学风化损耗的基本阳离子可以通过比较土层与成土母质之间元素组成的差异来计算。输入-输出指数的假设前提是研究的流域处于稳定状态,一般认为输入指数是大气沉降,输出指数是河流搬运溶解部分、悬浮的非岩屑成因部分和生物营养净吸收部分。Sr同位素在生物和化学作用过程中并不分馏,不同生态系统阳离子场中Sr同位素组成是大气和矿物风化来源的Sr的混合物。 相似文献
124.
Roland?StalderEmail author Stephan?Klemme Thomas?Ludwig Henrik?Skogby 《Contributions to Mineralogy and Petrology》2005,150(5):473-485
The incorporation of hydrogen into ferrosilite, Fe-bearing enstatite and orthopyroxene containing different trivalent cations (Cr3+ and Al3+, Cr3+ and Fe3+) was investigated experimentally at 25 kbar. Hydrogen concentration was determined by FTIR-spectroscopy on oriented crystal sections and by secondary ion mass spectroscopy, whereas Mößbauer spectroscopy and optical spectroscopy were used to characterise the valence state of Fe in orthopyroxene. Results suggest that hydrogen incorporation in ferrosilite is achieved by a similar mechanism as in pure enstatite. In Cr-bearing samples, however, hydrogen incorporation is reduced by the presence of other trivalent cations by an increased tendency to form Tschermaks substitutions, e.g. Si T 4+ + Mg M1 2+ ? Al T 3+ + Cr M1 3+ . Thus, hydrogen solubility in natural orthopyroxenes from the Earth’s mantle, containing significant amounts of Cr3+, Al3+, and Fe3+, may be much more limited than expected from their trivalent cation content, as a large fraction of the trivalent cations does not participate in H-incorporating reactions as 2 Mg M1 2+ ? M M1 3+ + VM1 + H i + . 相似文献
125.
树脂催化合成丁酸异戊酯的研究 总被引:5,自引:0,他引:5
研究了大孔强酸性阳离子树脂高温催化合成丁酸异戊酯的影响因素 ,得出了最佳工艺条件 ,酸产率高达 96%以上。该法流程简短、操作简便、污染少 ,产品质量好 ,酯含量超过 98% ,是取代旧工艺的理想方法。 相似文献
126.
对裂隙岩体的爆破破碎阻力特性进行了研究,提出了裂隙岩体爆破阻力矢量的概念和研究方法。以单元结构体作为主要研究对象,建立了爆破阻力矢量与岩体实际阻力矢量的关系模型。作为一种研究方法,它对裂隙岩体的爆破破碎的理论研究及施工技术的研究具有一定的实际意义。 相似文献
127.
水与岩土相互作用是导致岩土抗剪强度降低的主要原因之一,这种宏观表象是地下水与岩土发生了一系列复杂的力学、物理和化学方面相互作用的综合结果。因此,查明水与岩土的相互作用模式是掌握岩土抗剪强度变化机理的关键所在。本文以兰州地区红层风化泥岩为对象,采用直剪试验方法,初步探讨了快剪条件下,孔隙水化学成分及pH改变时,该类风化泥岩抗剪强度的变化特点。结果显示,在快剪条件下,水在该类风化泥岩抗剪强度中的力学效应(孔隙水压力效应)与物理、化学效应同时存在,但力学效应明显强于物理效应和化学效应。地下水物理效应和化学效应的强弱与风化泥岩可溶盐含量及其化学成分、粘粒含量及其矿物成分有关。 相似文献
128.
为了准确计算泥质砂岩储层的Qv,提出了利用核磁共振测井计算Qv的方法,通过对56块同时具有阳离子交换量和孔隙度、渗透率数据的岩心样品的分析,建立了阳离子交换量与综合物性指数的关系模型。为了解决准确而连续地计算综合物性指数的问题,提出了利用核磁共振测井横向驰豫时间几何平均值求取Swanson参数、进而利用Swanson参数获取综合物性指数的方法。同时利用核磁共振测井法、自然伽马测井相对值法、自然电位测井图版法3种计算Qv的方法对准噶尔盆地南缘4口井资料进行了处理,并对处理结果作了对比分析。结果表明:在泥质砂岩厚层段,3种方法都可以简单而有效地计算Qv。与岩心资料相比,核磁共振测井法计算的相对误差为13%,自然伽马测井法计算的相对误差为19%,自然电位测井法计算的相对误差为22%;在砂泥岩薄互层,用核磁共振测井法计算的Qv比其它两种方法计算的结果更为可靠,更能反映地层的真实情况。 相似文献
129.
氮迁移转化对地下水硬度升高的影响 总被引:15,自引:0,他引:15
城市地下水硬度升高是一个普遍的环境问题,研究表明地下水硬度高值区与硝酸盐污染在空间上的分布具有一致性。通过室内土柱试验和化学热力学模拟,讨论了污水入渗过程中氮迁移转化对水土系统钙镁迁移的影响。结果表明:在连续入渗条件下,阳离子交换作用是控制地下水硬度升高的主要过程;在间歇入渗条件下,硝化作用改变了土水系统的酸碱条件,使钙镁难溶盐溶解,导致地下水硬度升高。 相似文献
130.