Dissertation Research: Nitrogen Transformation and Transportation Along a Gradient in Soil Texture

输入生物圈的化学活性氮化合物，即活性氮，正在增加。 这些投入物具有有益的影响，包括增加作物产量，也具有有害的影响，如养分污染。 森林土壤可作为活性氮的汇和源。 确定森林土壤保持这种氮的机制是一个重要的研究目标。 这项研究将提高我们的理解，活性氮保持结合土壤碳和土壤质地到森林土壤氮保持的分析。 土壤碳能促进活性氮向非活性态转化。 相反，粗糙的土壤质地可以促进活性氮向地表和地下沃茨的运输。 这些过程的相对重要性将被评估沿着梯度的土壤碳和土壤质地在切萨皮克湾流域。 结果将被整合，以确定如何氮转化和运输相互作用，以控制生态系统的活性氮损失。 对促进氮保留的机制的进一步理解有助于确定活性氮何时、何地以及为什么被输送到地表和地下沃茨。 土壤质地为解释这些关系提供了一个广泛适用的框架。 由于土壤质地在地球仪上绘制得很好，因此这项研究的结果将使管理人员能够利用现有的土壤质地图来预测开放沃茨特别容易受到非点源营养物污染的地点和时间，并相应地管理景观。 一名本科生将参加这个项目，高中生将受益于从这项研究开发的教育材料。

Inputs to the biosphere of chemically active compounds of nitrogen, known as reactive nitrogen, are increasing. These inputs have beneficial effects including increased crop production, and deleterious effects such as nutrient pollution. Forest soils can serve as sinks and sources for reactive nitrogen. The identification of mechanisms that allow forest soils to retain this nitrogen is an important research goal. This research will improve our understanding of reactive nitrogen retention by incorporating soil carbon and soil texture into an analysis of forest soil nitrogen retention. Soil carbon can promote the transformation of reactive nitrogen into non-reactive forms. In contrast, coarse soil texture can promote the transportation of reactive nitrogen to surface and ground waters. The relative importance of these processes will be evaluated along gradients of soil carbon and soil texture in a Chesapeake Bay watershed. The results will be integrated to determine how nitrogen transformation and transportation interact to control ecosystem losses of reactive nitrogen. An improved understanding of the mechanisms promoting nitrogen retention can help to determine when, where and why reactive nitrogen is transported to surface and ground waters. Soil texture offers a broadly applicable framework for interpreting these relationships. Because soil texture is well-mapped across the globe, results from this research will enable managers to use existing soil texture maps to predict places and times where open waters are particularly susceptible to non-point nutrient pollution and to manage landscapes accordingly. An undergraduate student will participate in this project, and high school students will benefit from educational materials developed from this research.