DISSERTATION RESEARCH: Biological Uptake of Dissolved Organic Matter in Streams and Self-Priming Effect

论文研究：河流中溶解有机物的生物吸收和自吸效应

• 批准号: 1601155
• 负责人: Peter Raymond
• 金额: $ 2.13万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1601155&HistoricalAwards=false
• 关键词: DISSERTATION; RESEARCH; Biological; Uptake; Dissolved

Rivers and streams connect the land and the sea, and serve as the main transport channels for not only living organisms but also for chemical substances derived from plants, soils, animals, and humans. Inland waters, which include streams, rivers, ponds, lakes, and reservoirs, are also dynamic ecosystems where these substances are consumed and transformed. Among the major compounds in aquatic environments are organic molecules dissolved in the water, and they include a complex solution of individual molecules that can affect water color, drinking water quality, light availability, dissolved oxygen levels, and ecosystem function. Nevertheless, the understanding of how these organic molecules are processed remains limited, and this is especially true for larger systems like major rivers or entire drainage networks. This issue is addressed in this graduate student research project as the student seeks to discover how much of the organic molecules are removed by biological and non-biological processes in three streams in New England. This study builds upon existing research, applies a novel field method that characterizes the removal of dissolved organic matter (DOM) in a scalable manner, and hypothesizes that biological uptake of dissolved organic matter is a relatively minor component of the total removal. This hypothesis is postulated upon the preliminary data from a method where oxygen reduction due to heterotrophy accounted for only small portion of dissolved organic matter removal in streams. The novel field method involves pulse injection of filtered maple leaf leachate into three different streams in Connecticut, Massachusetts, and Vermont where streams are constantly monitored with multi-probe sondes to detect changes in conductivity, DOM concentration, and oxygen level as the pulse of organic matter travels downstream. The solute transport data and grab samples acquired during the experiments are then used to calculate the total DOM removal, oxygen uptake due to heterotrophy, and organic matter quality change due to heterotrophy. In addition to the primary hypothesis, the preliminary data also hints at a novel priming mechanism where in-stream utilization of organic matter pulse in streams leads to boosted bioavailability by unlocking previous unavailable labile organic matter. The second hypothesis, aptly named "self-priming," aims to verify the presence and mechanism of this novel concept.

河流和溪流连接土地和大海，不仅是生物的主要运输通道，而且还可以作为植物，土壤，动物和人类衍生的化学物质。内陆水域包括流，河流，池塘，湖泊和水库，也是动态的生态系统，在这些生态系统中，这些物质被消耗和转化。在水生环境中的主要化合物中，有机分子溶于水中，其中包括一个复杂的单个分子解决方案，这些分子可以影响水颜色，饮用水质量，光的可用性，溶解的氧气水平和生态系统功能。 然而，对这些有机分子的处理方式的理解仍然有限，对于大河流或整个排水网络等较大的系统尤其如此。该问题在该研究生研究项目中解决了这个问题，因为学生试图发现新英格兰三个流的生物学和非生物学过程消除了多少有机分子。这项研究以现有研究为基础，采用了一种新型的现场方法，该方法以可扩展的方式表征了溶解有机物（DOM）的特征，并假设生物学摄取溶解有机物是总去除的相对较小的组成部分。该假设是在从一种方法的初步数据上进行假设，在这种方法中，由于杂物造成的氧气减少仅占溪流中溶解有机物的一小部分。新型野外方法涉及将过滤后的枫叶浸出物脉冲注入康涅狄格州，马萨诸塞州和佛蒙特州的三个不同的流中，在那里不断使用多探针sondes来监测流，以检测有机物脉搏的电导率，DOM浓度和氧气水平的变化。然后，使用在实验期间获得的溶质传输数据和获取样品来计算总DOM去除，由于异质营养而引起的氧气吸收以及由于异植物而引起的有机物质量变化。除了主要假设外，初步数据还暗示了一种新颖的启动机制，在这种机制中，流中有机物脉冲的流化利用会通过解锁先前不可用的不稳定有机物来提高生物利用度。第二个假设恰当地命名为“自我宣传”，旨在验证这一新颖概念的存在和机制。