Doctoral Dissertation Research: Sunlight stimulates a spectrum of microbial CO2 production from permafrost carbon

博士论文研究：阳光刺激微生物从永久冻土碳中产生二氧化碳

• 批准号: 2228992
• 负责人: Rose Cory
• 金额: $ 2.05万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-02-15 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2228992&HistoricalAwards=false
• 关键词: Doctoral; Dissertation; Research; Sunlight; stimulates; Doctoral; Dissertation; Research; Sunlight; stimulates

We need to better understand and reduce greenhouse-gas emissions to meet the Paris Agreement goal of limiting global warming to a 1.5 ºC increase. The thawing of organic carbon stored in Arctic permafrost soils ultimately creates carbon dioxide (a greenhouse gas). Further, this process is predicted to amplify with additional global warming, however, to an unknown extent. Therefore, we need to quantify the extent to which carbon dioxide released from thawing permafrost will amplify global warming; this is one of the most urgent questions that Arctic scientists must answer. To address this, this project will make measurements to quantify how much carbon dioxide is produced when organic carbon from thawing permafrost soils flows into sunlit arctic surface waters. The project will also leverage an existing University of Michigan program called Earth Camp to engage high school students about environmental sciences through hands-on experiences and outdoor activities.As water moves through thawed soil it dissolves organic carbon. This dissolved organic carbon (DOC) then flows into streams, ponds, and lakes. Once in surface waters, both microbes and sunlight oxidize DOC to CO2. DOC exposed to sunlight is easier for microbes to oxidize to CO2 compared to the same DOC kept in the dark. However, the sunlight reaching surface waters spans a spectrum of wavelengths, from the high-energy ultraviolet (UV) to the lower-energy visible light. A critical unknown is which wavelengths of sunlight from the UV to the visible are most efficient at helping microbes to oxidize DOC to CO2. If visible light helps microbes oxidize more DOC to CO2 than currently assumed, the CO2 produced from this process could be double the current estimate because there is more visible light reaching surface waters than UV light. In addition, different wavelengths of sunlight may help microbes oxidize a fraction of DOC that, in the absence of sunlight, microbes would not be able to oxidize to CO2. This fraction of DOC that is difficult to oxidize may be some of the oldest carbon that has been frozen for thousands of years in permafrost soils. This project will test how efficiently sunlight helps microbes oxidize ancient permafrost DOC by measuring the amount and radiocarbon age of the CO2 produced from microbial oxidation of permafrost DOC exposed to UV and visible sunlight. Results from this project will enable predictions of the CO2 produced from ancient permafrost organic carbon thawed and exported to sunlit surface waters, which is critical knowledge needed to quantify arctic amplification of global warming.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

我们需要更好地理解和减少温室气体排放，以实现巴黎协议的目标，即将全球变暖限制为增加1.5ºC。储存在北极冻土土壤中的有机碳的解冻最终会产生二氧化碳（一种温室气）。此外，预计该过程将在未知的程度上随着其他全球变暖的速度扩大。因此，我们需要量化二氧化碳从融化多年冻土释放的程度将扩大全球变暖。这是北极科学家必须回答的最紧迫的问题之一。为了解决这个问题，该项目将进行测量，以量化有机碳从融化的多年冻土土壤中流入阳光北极的地表水时产生多少二氧化碳。该项目还将利用现有的密歇根大学计划，称为Earth Camp，通过动手体验和户外活动吸引高中生有关环境科学的知识。随着水通过融化的土壤移动，它溶解了有机碳。然后将其溶解的有机碳（DOC）流入溪流，池塘和湖泊。一旦进入地表水，微生物和阳光氧化物均以二氧化碳的形式。与在黑暗中保持相同的DOC相比，微生物暴露于阳光的DOC更容易氧化为CO2。然而，到达地表水的阳光跨越了一系列波长，从高能紫外线（UV）到低能量可见光。一个关键的未知是从紫外线到可见的阳光波长最有效地帮助微生物到氧化物DOC到CO2。如果可见光可以帮助氧化物对CO2的氧化物比目前所假设的更多，那么从此过程中产生的二氧化碳可能是当前估计值的两倍，因为与紫外线相比，到达地表水的可见光更多。此外，不同的阳光波长可能有助于微生物氧化一小部分文档，在没有阳光的情况下，微生物将无法氧化为CO2。难以氧化的DOC的一部分可能是在多年冻土土壤中冻结数千年的最古老的碳。该项目将通过测量暴露于紫外线和可见阳光的多种冻土DOC产生的二氧化碳的量和放射性碳年龄来测量微生物如何有效地帮助微生物氧化古代冻土DOC。 Results from this project will enable predictions of the CO2 produced from ancient permafrost organic carbon thawed and exported to sunlit surface waters, which is critical knowledge needed to quantify arctic amplification of global warming.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.