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.

河流和小溪连接着陆地和海洋，不仅是生物的主要运输通道，也是植物、土壤、动物和人类的化学物质的主要运输通道。内陆水域，包括溪流、河流、池塘、湖泊和水库，也是这些物质被消耗和转化的动态生态系统。水生环境中的主要化合物是溶解在水中的有机分子，它们包括单个分子的复杂溶液，这些分子可以影响水的颜色、饮用水质量、光的可用性、溶解氧水平和生态系统功能。然而，对这些有机分子如何被处理的理解仍然有限，特别是对于像主要河流或整个排水网络这样的大型系统。这个问题在这个研究生研究项目中得到解决，因为学生试图发现在新英格兰的三条河流中有多少有机分子被生物和非生物过程去除。本研究建立在现有研究的基础上，采用了一种新的现场方法，以可扩展的方式表征溶解有机物（DOM）的去除，并假设溶解有机物的生物吸收是总去除的一个相对较小的组成部分。这一假设是根据一种方法的初步数据提出的，其中由于异养引起的氧还原只占溪流中溶解有机物去除的一小部分。这种新颖的现场方法包括将过滤后的枫叶渗滤液脉冲注入康涅狄格州、马萨诸塞州和佛蒙特州的三条不同的溪流中，在这些溪流中，随着有机物质的脉冲流向下游，溪流被多探头探头不断监测，以检测电导率、DOM浓度和氧气水平的变化。然后利用实验中获得的溶质输运数据和抓取样品计算DOM的总去除量、异养引起的摄氧量和异养引起的有机质质量变化。除了主要假设之外，初步数据还暗示了一种新的启动机制，即溪流中有机物脉冲的流内利用通过释放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“自启动”，旨在验证这个新概念的存在和机制。