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

>将研究地形对阿拉斯加冻土带沿海拔梯度影响土壤酸度和h +收支的机制。该提案的一个中心假设是，冻土带海拔梯度中h +的生产和消耗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诱导的氧化还原电位变化。为了检查土壤酸度的地形变化并检验中心假设，将对布鲁克斯山脉北部萨加瓦尼克托克河沿岸海拔梯度约300米的六个生态系统进行检查。研究的一部分将是描述性的。酸度的模式将通过测量自由h +、可滴定酸度、可交换阳离子和交换络合物的酸强度来确定。此外，还将估算h +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。该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对h +生产的控制。将使用标准方法的组合来衡量H.+预算的各个组成部分。其中包括：1)使用乙炔块程序进行厌氧实验室试验的反硝化；2)埋袋法硝化；3)通过生物量积累过程实现植物离子平衡。h +预算有助于验证我们对生态系统中生物地球化学循环的理解。更好地了解冻土带的生物地球化学循环对其进行明智的管理是必要的。他是一位富有成效的研究人员，在开发h +离子预算方面拥有丰富的经验。他能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.