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模拟不同气候条件下碳酸盐岩风化作用的淋溶实验研究

ISSN号：1001-4810
期刊名称：中国岩溶
时间：2012
页码：361-376
分类：P599[天文地球—地球化学;天文地球—地质学]
作者机构：[1]南华大学核资源与核燃料工程学院,湖南衡阳421001, [2]中国科学院地球化学研究所/环境地球化学国家重点实验室,贵州贵阳550002
相关基金：国家自然科学基金项目（40973070）;国家基金委创新团队项目（40721002）;中国科学院战略性先导科技专项（XDA05070400）致谢：刘志明与孙承兴在野外采样过程中给予了大力帮助,审稿专家及编辑对论文提出了建设性的修改意见,在此一并致谢.
相关项目：西南喀斯特流域物质循环的生物地球化学过程与生态环境效应

关键词：碳酸盐岩风化壳, 岩-土界面, 岩粉层, 风化作用, 淋溶模拟, 贵州, weathering crust of carbonate rock, rock-soil interface, rock powder layer, weathering, leaching simulation, Guizhou Province

中文摘要：

通过模拟干热、湿热与干冷3种气候条件，以饱和CO2水作为淋溶液，对黔中岩溶区3条碳酸盐岩风化壳岩一土界面的岩粉层试样进行了淋溶实验（其中干热、湿热条件下淋溶到残余酸不溶物阶段），对淋出液的pH值以及主要造岩元素的浓度进行了动态分析。结果表明，碳酸盐岩风化壳岩-土界面由岩到土的转变过程中，伴随碳酸盐的溶蚀，酸不溶物已表现出明显的风化倾向。碳酸盐的溶蚀强度表现为干冷〉干热〉湿热的变化趋势。温度低，碳酸盐的溶解速率大；排水条件好，碳酸盐溶解释放的Ca、Mg易随风化流体排出体系。对于酸不溶物组分，淋溶实验中有：（1）K、Na、Mg、Si、P的载体矿物风化强度在干热条件下最大（至于Ca，由于方解石与白云石均是其主要的载体矿物，酸不溶物相中的Ca难以在淋出液中有效识别）。在干冷与湿热之间，K、Na、Mg等盐基离子的溶出能力大多表现为湿热〉干冷，指示了温度对盐基离子释放强度的重要制约作用；而Si和P未表现出一致的变化趋势，可能源于淋溶体系微环境的差异。（2）Fe与Mn表现出弱迁移性。其中，Fe在干冷环境下淋出强度最弱，说明温度是制约含Fe矿物分解速率的重要因素。而Fe在干热与湿热之间，以及Mn在3种淋溶条件下，未呈现出一致的变化趋势。（3）Al和Ti在碳酸盐岩风化过程中表现出强烈的惰性。

英文摘要：

By simulating dry-hot, wet-hot and dry-cool climate respectively and taking water saturated with CO2 as leaching solution, a leaching experiment is carried out （of them, leaching experiment simulating dry- hot and wet-hot climate reached acid-insoluble residue stage） on rock powder layer samples from rock-soil in- terface in 3 weathering profiles in central Guizhou karst region. The results indicate that acid-insoluble resi- dues have shown significant weathering tendency along with carbonate dissolution at rock-soil interface of weathering profiles. In three kinds of different leaching conditions, the dissolution intensity of carbonate dis- plays the trend of dry-cool〉dry-hot〉wet-hot. When the temperature is low, the dissolution rate of carbon- ate is high, and as the drainage condition is good, Ca and Mg released by carbonate dissolution are easy to be discharged from the system. Concerning the acid-insoluble residues in carbonate rocks, firstly, the weathe- ring intensity of carrier minerals of K, Na, Mg, Si and P is the strongest in dry-hot condition （as for Ca, for both calcite and dolomite are its major carrier minerals in carbonate rocks, it is different to effectively identi- fy Ca deriving from acid-insoluble phase in leaching sloution）. Between dry-cool and wet-hot, the release a- bility of K, Na and Mg, i.e. base cations, from the system, in most cases, is for wet-hot, dry-cool, and it is indicated that the temperature severely constrains the release strength of base cations; the release ability of Si and P is not demonstrated a consistent trend in three samples, and it may be caused by the differences in microenvironment of the leaching system. Secondly, Fe and Mn are weak migration elements. Among them, the leaching intensity of Fe in dry-cool condition is the weakest, and it indicates that the temperature is an important factor to constrain the decomposition rate of Fe-containing minerals. While leaching intensity of Fe between dry-hot and wet-hot and Mn among three kinds of different le

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