Identification and Role of Low Molecular Weight Organic Acids in a Subalpine Ecosystem

将在太平洋西北部的针叶生态系统中研究土壤中低分子有机酸的来源和鉴定。在这些生态系统中，这些酸与富里酸一起可能会推动土壤形成过程，即豆腐化。其中一些酸可能控制土壤溶液中钙和铝对植物的有效性。这项工作可以很大程度上解释针叶树对高铝土壤的耐受性，以及在这些条件下根际有效钙的维持。这项工作对于理解是什么控制着从土壤到森林景观中溪流中溶解的有机碳和铝的浓度也具有重要意义。本课程将研究三种可能的有机酸来源：根分泌物、腐烂的有机质和菌根真菌。将对有机酸来源进行实地和实验室研究。实地研究将包括比较无根地和对照地土壤中的有机酸。土壤溶液将通过蒸馏法和萃取法进行采样。将使用各种最先进的技术来识别低分子量酸。这些技术包括气相色谱、高压液相色谱和GC/MS，将使用一种特殊的电子显微镜应用来确定土壤-根基质中铝的存在形式。乌戈利尼博士在这一领域有着杰出的研究记录。他在华盛顿大学获得的机构支持是一流的。

The origin and identity of low molecular weight organic acids in soils will be studied in coniferous ecosystems in the Pacific Northwest. These acids along with fulvic acids may drive the soil formation process, podsolization, in these ecosystems. Some of these acids may control the availability of Ca and Al to plants from soil solution. The work could go a long way toward explaining the tolerance of conifers to high Al soils and to the maintenance of available Ca in the rhizosphere under these conditions. The work is also significant to understanding what controls the concentrations of dissolved organic carbon and Al that move from the soil to streams in the forested landscape. Three potential sources of organic acids will be examined; root exudates, decaying organic matter, and mycorrhizal fungi. Both field and laboratory studies of organic acid sources will be undertaken. Field research will include comparison of organic acids in soils of root-free and control plots. Soil solutions will be sampled by lysimetry and extractions. A variety of state-of-the-art techniques will be used to identify low molecular weight acids. These techniques include gas chromatography, high pressure liquid chromatography and GC/MS. The forms in which Al exist in the soil-root matrix will be determined using a special application of electron microscopy. Dr. Ugolini has an outstanding research record in this area. The institutional support available to him at the University of Washington is first-rate.