The Application Of Scaling Rules To Energy Flow In Stream Ecosystems

摘要卡普兰0109122，研究人员建议估计运输中的溶解有机物(DOM)对河流生态系统新陈代谢的支持作用。该项目的具体目标是估计DOM的质量通量(例如，从水柱到河床的通量的速率)，将其表示为几个不稳定类的通量之和，并表征每个不稳定类中DOM的各自的浓度和吸收长度系数。吸收长度很容易通过涉及深度和水流速度的比例关系转换为传质系数或周转率。量化河流中天然DOM的吸收类似于描述磷或铵的吸收(或螺旋式上升)，但由于天然DOM的多样性(即，它由一系列不同稳定性的化合物组成)以及无法获得同位素标记的天然DOM的事实，使其变得复杂。该项目将使用13C标记的DOM，这些DOM是在13C的大气中生长植物产生的。13C-DOM的纵向吸收将被分解为多个吸收长度(对应于多个稳定级别)，估计为指数曲线的总和。此外，实验室生物反应器中天然(12C)DOM的吸收动力学将与标记的13C-DOM的动力学进行比较，这种比较将被用来衡量13C-DOM注射的结果，以适当地描述天然DOM在溪流中的吸收。

Abstract Kaplan 0109122 The investigators propose to estimate the contribution of dissolved organic matter (DOM) in transport to the support of stream ecosystem metabolism. The specific objective of this project is to estimate the mass flux of DOM (e.g., the rate of flux from the water column to the streambed), to represent this as the sum of fluxes from several lability classes, and to characterize the respective concentration and uptake length coefficient of DOM in each lability class. Uptake length converts easily to mass transfer coefficient or turnover rate through scaling relationships involving depth and water velocity. Quantifying the uptake of natural DOM in the stream is analogous to describing the uptake (or spiraling) of phosphorus or ammonium, but is complicated by the diversity of natural DOM (i.e. it consists of an array of compounds of varying lability), and the fact that isotopically-labeled natural DOM is not available. This project will use 13C-labeled DOM generated by growing plants in a 13C atmosphere. The longitudinal uptake of 13C -DOm will be resolved into multiple uptake lengths (corresponding to multiple lability classes), estimated as the sum of exponential-curves. In addition, the uptake kinetics of natural (12C) DOM in laboratory bioreactors will be compared to those of the labeled 13C-DOM, and this comparison will be used to scale the results of the 13C-DOM injection, to appropriately describe the uptake of natural DOM in the stream.