Biogeochemical Weathering Controls on Soil Formation and Landscape Development

摘要生物地球化学风化作用控制着土壤的形成和景观发育。土壤生产力定义为基岩(在本研究中为化学风化的花岗闪长岩)转化为可动层(土壤，由花岗岩质地损失定义)的速率。以往的研究已经建立了土壤生产率与土层厚度之间的反相关关系形式。然而，这些研究没有将侵蚀与景观降低期间的溶质流失进行比较，也没有详细考虑在土壤形成之前和通常之后必须进行的生物地球化学风化过程。在这个项目中，质量守恒方程将利用地球化学示踪结果和现有的宇宙成因测年信息来求解，以确定澳大利亚东南部Bempka花岗闪长岩在景观开发过程中由于侵蚀和溶质损失而造成的长期质量转移。将评估溶质与侵蚀通量随土壤厚度和景观位置的变化，并将研究风化花岗岩中溶质损失率(在土壤形成之前)、土壤厚度和微生物过程之间的可能关系。该分析还将得出单位时间单位面积陆地上大多数元素的长期侵蚀和溶质损失值。这项调查扩展了以前的地貌学方法，将生物地球化学以及生物物理风化对土壤形成和景观演变的贡献纳入其中。这项研究的更广泛影响将源于对控制土壤形成速度的因素的新见解，对地貌对扰动的反应过程的更好理解，以及对海洋长期沉积物和溶质通量的量化。

AbstractBiogeochemical weathering controls on soil formation and landscape development.The soil production rate is defined as the rate at which bedrock, in this study chemically weathered granodiorite, converts to a mobile layer (soil, defined by loss of granitic texture). Previous studies have established the form of the inverse relationship between soil production rates and soil thickness. However, these studies have not compared erosion to solute losses during landscape lowering, or incorporated detailed consideration of the biogeochemical weathering processes that must precede, and generally follow, soil formation. In this project, conservation of mass equations will be solved using geochemical tracer results and existing cosmogenic dating information to determine long-term mass transfers due to erosion and solute loss during landscape development on the Bemboka Granodiorite in SE Australia. Variation in solute versus erosional fluxes with soil thickness and landscape position will be evaluated, and possible relationships between the solute loss rates (prior to soil formation), soil thickness, and microbial processes in the weathered granite will be examined. The analysis will also yield values for long-term erosion and solute losses for most elements per unit area of land surface per unit time. This investigation extends prior geomorphological approaches to incorporate biogeochemical as well as biophysical weathering contributions to soil formation and landscape evolution. Broader impacts of the research will stem from new insights into factors controlling rates of soil formation, improved understanding of the processes by which landscapes respond to perturbation, and the quantification of long-term sediment and solute fluxes to the oceans.