The Role of Hydrologic Inputs in the Balance of Carbon Dioxide in Small Lakes

湖的表层水不断地，有时是湍急的，与上面的大气层接触。这种接触使溶解在水中的气体与大气中的气体保持平衡。尽管有这种气体交换，但湖泊表面水域中的某些气体始终与大气失去平衡。例如，在大多数湖泊中，二氧化碳的分压往往比人们预期的与大气平衡时高出几倍。由于二氧化碳是生物呼吸的最终产物，许多研究人员认为湖泊中二氧化碳的过饱和是新陈代谢的结果。也就是说，这些研究人员假设水体中的呼吸作用超过光合作用。要做到这一点，湖泊的新陈代谢必须得到来自陆地分水岭的有机碳的补贴。然而，其他过程也可能导致二氧化碳过饱和。这包括：高过饱和地下水的输入；或铁或硫等还原化学物种的输入，这些化学物种的氧化产生酸度并将重碳酸盐转化为二氧化碳。这项研究旨在确定哪些过程是导致湖泊二氧化碳升高的最重要因素。研究人员建议通过研究镜湖来确定水文输入作为湖水二氧化碳升高的原因所起的作用。镜湖是哈伯德布鲁克生态系统研究的一部分，研究非常深入。这个湖的初步二氧化碳预算表明，大气中的二氧化碳损失比所有已知过程的总和大几倍。这项提议的主要目标是平衡这种二氧化碳质量平衡。研究人员假设，二氧化碳的重大直接或间接输入被低估了，因为水文事件的作用和地下水输入的空间变化尚未纳入输入计算。研究人员将创建一个空间上明确的水文模型，以确定二氧化碳、DOC和消耗碱度的氧化还原成分的输入。镜湖的这项工作是可能的，因为与美国地质勘探局的水文学家和镜湖流域的一系列连续监测井的持续合作，以及持续监测地表水和地表水化学的输入和输出。一名研究生和两名本科生将在该项目中接受水文学和湖湖学之间的培训。此外，这项工作将与哈伯德·布鲁克生态系统研究的更大教育推广计划相联系，这是一个LTER网站。镜湖的研究将成为科学链接的新焦点。为中学生准备的节目。

0309257ColeThe surface waters of lakes are in constant, and sometime turbulent, contact with the overlying atmosphere. This contact allows gases dissolved in the water to equilibrate with those in the atmosphere. Despite this gas exchange, certain gases in the surface waters of lakes are consistently out of equilibrium with the atmosphere. The partial pressure of carbon dioxide, for example, tends to be several-fold higher in most lakes than one would expect from equilibrium with the atmosphere. Because CO2 is an end-product of biological respiration, many researchers have assumed that this CO2 supersaturation in lakes is the result of metabolism. That is, these researchers assume that respiration exceeds photosynthesis in the water body. For this to occur the lake's metabolism must be subsidized by organic C from the terrestrial watershed. Other processes, however, can also lead to carbon dioxide supersaturation. These include: the input of highly supersaturated ground water; or the input of reduced chemical species such as iron or sulfur, the oxidation of which generates acidity and converts bicarbonate to carbon dioxide. The research here is designed to determine which processes are most important in causing elevated CO2 in lakes.The researchers propose to determine the role of hydrologic inputs as a cause for elevated CO2 in lake water by studying, Mirror Lake, a very-well studied lake which is part of the Hubbard Brook Ecosystem Study. The preliminary CO2 budget for this lake suggests that the loss of CO2 to the atmosphere is several-fold larger than can be accounted for by the sum of all known processes. The major goal of this proposal is to balance this CO2 mass balance. The researchers hypothesize that significant direct or indirect inputs of CO2 have been underestimated because the role of hydrologic events, and spatial variation in ground water inputs have not yet been incorporated into the input calculations. The researchers will create a spatially explicit hydrologic model to determine the inputs of CO2 , DOC, and alkalinity-consuming redox constituents. This work is possible at Mirror Lake because of an ongoing collaboration with hydrologists at USGS and an extensive series of continuously monitored wells in the Mirror Lake watershed, and continuously monitored inputs and outputs of surface waters and surface water chemistry.One graduate and two undergraduate students will receive training at the interface between hydrology and limnology in the program. Additionally, this work will be linked to the larger educational outreach program of the Hubbard Brook Ecosystem Study, an LTER site. The Mirror Lake research will be a new focus of the Science Links. Program for middle school students.