Rivers, chemical weathering and Earth's climate   总被引：4，自引：0，他引：4  

Bernard Dupr  Cline Dessert  Priscia Oliva  Yves Goddris  Jrme Viers  Louis Franois  Romain Millot  Jrme Gaillardet 《Comptes Rendus Geoscience》2003,335(16):1141-1160

We detail the results of recent studies describing and quantifying the large-scale chemical weathering of the main types of continental silicate rocks: granites and basalts. These studies aim at establishing chemical weathering laws for these two lithologies, describing the dependence of chemical weathering on environmental parameters, such as climate and mechanical erosion. As shown within this contribution, such mathematical laws are of primary importance for numerical models calculating the evolution of the partial pressure of atmospheric CO₂ and the Earth climate at geological timescales. The major results can be summarized as follow: (1) weathering of continental basaltic lithologies accounts for about 30% of the total consumption of atmospheric CO₂ through weathering of continental silicate rocks. This is related to their high weatherability (about eight times greater than the granite weatherability); (2) a simple weathering law has been established for basaltic lithologies, giving the consumption of atmospheric CO₂ as a function of regional continental runoff, and mean annual regional temperature; (3) no such simple weathering law can be proposed for granitic lithologies, since the effect of temperature can only be identified for regions displaying high continental runoff; (4) a general law relating mechanical erosion and chemical weathering has been validated on small and large catchments. The consequences of these major advances on the climatic evolution of the Earth are discussed. Particularly, the impacts of the onset of the Deccan trapps and the Himalayan orogeny on the global carbon cycle are reinvestigated. To cite this article: B. Dupré et al., C. R. Geoscience 335 (2003).  相似文献   

中尺度非静力模式中常用气压分离技术的研究          下载免费PDF全文

廖洞贤  孙岚 《大气科学》2003,27(2):203-211

分析了气压分离和不分离,在几种不同的层结情况下,垂直气压梯度的截断误差.结果表明:基本场取法不当,会引起巨大的截断误差,甚至和不分离时相当;反之,则较小.根据计算,提出了一种取基本场的方法,在一定条件下,可以使气压偏差的垂直梯度的截断误差比不分离时的相应误差小一个量级,从而,可以取较小的垂直分辨率.  相似文献   

杭州市化工园区选址的气象环境与评估的数值模拟研究          下载免费PDF全文

徐集云  顾骏强陈燕 吴涧 《气象科技》2003,31(6):334-339344

城市化是国家社会发展的必然趋势，为了在新一轮城市总体规划中能保证杭州市的大气环境质量，优化不同空间尺度的城市规划，协调城市发展与保护环境的关系，本文利用一个三维非静力区域边界层数值模式，对一些典型天气条件下杭州地区的风场和气温的空间分布特征进行模拟分析，并以此为依据，给出选取化工园区的位置的评估意见。模拟结果表明，化工园区的选址宜考虑在杭州市的西南方向。  相似文献   

地下气体运移变化的物理化学机制研究   总被引：1，自引：1，他引：1       下载免费PDF全文

高清武 《地震地质》1997,19(1):54-58

在河北省怀来县后郝窑地区，对地下气体运移变化的影响因素进行了野外模拟实验研究。选择３个试验点，对地下气体的扩散作用，物理化学影响因素及水压效应等进行了模拟实验，主要研究Ｈ２，ＣＯ２气体运移变化机制。实验研究表明，Ｈ２，ＣＯ２气体运移变化机制不尽相同，水压效应对Ｈ２，ＣＯ２等地下气体运移影响相当明显  相似文献   

Disequilibrium for Ca during growth of pelitic garnet   总被引：14，自引：1，他引：14  

C. B. CHERNOFF  & W. D. CARLSON 《Journal of Metamorphic Geology》1997,15(4):421-438

Compositional zoning in hundreds of almandine-rich garnets in amphibolite by facies micaceous quartzites from the Picuris Range, north-central New Mexico USA, indicates that although Mn, Mg and Fe achieve chemical equilibrium at hand-sample scale during garnet growth, Ca does not. Instead, Ca concentrations at the surface of growing garnets appear to depend strongly on kinetic factors that govern the local chemical environment, yielding disequilibrium for Ca at scales larger than the region immediately surrounding an individual porphyroblast. Detailed zoning profiles were obtained for 371 garnet crystals in a small volume of a single sample of garnetiferous quartzite, and core analyses were made of 97 additional crystals. Each analysis was made on a section that passed precisely through the morphological centre of the crystal, located by means of 3-D imagery from computed X-ray tomography. The data reveal strong correlations between crystal size and concentrations of Mn, Mg and Fe (but not Ca) in garnet cores; a relationship between crystal size and isolation; rigorous cross-correlations among concentrations of Mn, Mg and Fe (but not Ca); and systematic variations in Ca concentrations as a function of crystal size and core composition that are anomalous in comparison to the behaviour of the other divalent cations. We interpret these observations as the result of thermally accelerated diffusion-controlled garnet growth, in circumstances that promoted rapid intergranular diffusion and thus rock-wide equilibration of Mn, Mg and Fe, but that prevented equilibration at similar scale for Ca because of its more sluggish intergranular diffusion. The anomalous behaviour of Ca is made evident in these garnets by the presence of sharp spikes in Ca concentration, which are demonstrably not a consequence of any simultaneous rock-wide event, such as a change in pressure, temperature, or some other intensive parameter. Instead, Ca concentrations probably reflect the local extent of reaction in the immediate vicinity of each porphyroblast. To the degree that such kinetic factors introduce departures from chemical equilibrium for Ca, thermobarometric estimates that involve grossular contents of pelitic garnet will be in error.  相似文献   

氟离子对在河口区存在形态的理论研究          下载免费PDF全文

范志杰  宋春印 《水科学进展》1997,8(1):54-58

利用Davies离子强度校正方程,把在标准条件下获取的氟离子对的化学稳定数校正到35%的海水条件下,并应用逐步凑分法计算出F-离子对的几种存在形式:游离态F-占49.9%,MgF+占46.8%,其余为CaF+和NaF0.  相似文献   

悬浮液进样—石墨炉原子吸收测定钒钛磁铁矿中痕量镓   总被引：5，自引：0，他引：5  

张秀荣  单孝全 《岩矿测试》1997,16(1):60-64

研究了悬浮液进样＿石墨炉原子吸收测定钒钛磁铁矿中痕量镓的分析方法。以Ｎｉ（Ⅱ）作为基体改进剂时，可直接用镓标准溶液进行校准。样品粒度＜３８μｍ、悬浮液中试样质量浓度在０１～８０ｇ／Ｌ、含镓质量浓度不超过１００μｇ／Ｌ时呈良好线性关系，检出限为２４μｇ／Ｌ镓。用所拟方法测定了含镓量在１６～４２μｇ／ｇ的标准矿样，结果与标准值相符，６次平行测定的相对标准偏差不超过９％，满足痕量分析的要求。  相似文献   

榴辉岩中铁铝榴石的测定方法研究   总被引：3，自引：1，他引：3  

黄宝贵  柳建春 《岩矿测试》1997,16(4):241-244254

对国内主要矿区铁铝石榴子石纯矿物中铁的价态规律进行了研究。证明其所含Ｆｅ均以Ｆｅ＾２＋为主，其质量分数在８３－９４，并将Ｆｅ＾２＋这特征性成分用于某地榴辉岩中铁铝榴石的间接测定，获得结果与焙烧磁化－磁选法一致且精度好，较磁化法简便，快速。  相似文献   

遥感技术在化工环境保护中的应用     

邢耶  杨泽元 《化工矿产地质》1997,19(3):189-192

遥感技术获取的可见光、红外及微波信息，可以对化工企业及化学矿山环境污染（水、粉尘、大气、废渣污染等）及环境地质灾害（滑坡、泥石流、地面塌陷等）进行实时动态监测，并可获得较高的社会经济效益，达到地面环保及常规环境地质工作难以达到的效果。特别是对重点大中型化工企业及化学矿山建立环境遥感信息动态监测系统，可以为国家决策部门及时准确地提供环境治理和改造的依据。  相似文献   

论湖南柿竹园多金属矿床成岩成矿的化学模式─—与毛景文先生等商榷   总被引：2，自引：0，他引：2  

郑大中  郑若锋 《四川地质学报》1997,(4)

从湖南柿竹园多金属矿床成岩成矿的事实出发，用化学基本定律对其矽卡岩的形成，蚀变及成岩成矿的化学反应方程式进行研讨，建立了比较符合矿床实际与地球化学理论的化学模式。认为地球科学与化学是在相互交叉，相互渗透，相互促进中共同发展的。  相似文献