Influence of Topography on Soil Acidity and Hydrogen Ion Budgets in an Arctic Landscape

将研究阿拉斯加冻土带地形影响土壤酸度和沿海拔梯度的H收支的机制。该提议的一个中心假设是，苔原海拔梯度上的H.生产和消费主要受地下化学和微生物过程的调节，这些过程依赖于地形引起的氧化还原电位的变化。为了研究土壤酸度的地形变化并验证中心假设，将研究布鲁克斯山脉以北萨加瓦尼尔克托克河岸海拔约300米处的六个生态系统。研究的一部分将是描述性的。酸度的模式将通过测量游离态H、可滴定的酸度、可交换阳离子和交换络合物的酸强度来确定。此外，还将估计人力资源预算的主要组成部分，包括大气投入、内部生态系统生产和消费以及出口。这项研究还将包括实验操作，以测试沿海拔梯度的六个生态系统中的三个生态系统的H.生产控制。将使用标准方法的组合来衡量人力资源预算的各个组成部分。其中包括：1)利用乙炔阻滞法进行厌氧实验室测定的反硝化作用；2)采用埋袋法进行硝化作用；以及3)通过生物量积累过程进行植物离子平衡。预算用于验证我们对生态系统中生物地球化学循环的理解。需要更好地了解冻土带中的生物地球化学循环，才能对其进行明智的管理。宾利博士是一位多产的研究人员，他在制定氢离子预算方面拥有丰富的经验。他可以得到的机构支持非常好。

>The mechanisms by which topography influences soil acidity and H.+ budgets along an elevation gradient in the Alaskan tundra will be studied. A central hypothesis of the proposal is that H.+ production and consumption in a tundra elevation gradient are regulated primarily by belowground chemical and microbial processes that depend on topographically induced variation in redox potentials. To examine the topographic variation in soil acidity and test the central hypothesis, six ecosystems along an elevation gradient of about 300m on the banks of the Sagavanirktok River, north of the Brooks Range, will be examined. Part of the study will be descriptive. Patterns of acidity will be determined by measuring free H.+, and titratable acidity, exchangeable cations, and the acid strength of the exchange complex. In addition, estimations will be made of the major components of H.+ budgets, including atmospheric inputs, internal ecosystem production and consumption, and export. The study will also include experimental manipulations to test the controls of H.+ production in three of the six ecosystems along the elevation gradient. A combination of standard methods will be used to measure the various components of the H.+ budget. Among these are: 1) denitrification by anaerobic laboratory assays using the acetylene block procedure; 2) nitrification by the buried bag procedure; and 3) plant ion balance by the biomass accumulation procedure. A H.+ budget serves to validate our understanding of biogeochemical cycling in an ecosystem. Better understanding of biogeochemical cycling in the tundra is needed for its wise management. Dr. Binkley is a productive researcher who has substantial experience in developing H.+ ion budgets. The institutional support available to him is very good.