METHANE AT THE ZERO CURTAIN

在北极秋季有很长一段时间，大部分土壤剖面在0°C附近悬浮。研究人员提出，一年中的这个时候可能拥有更好地了解北极生态系统如何受到气候变化影响所需的关键信息。研究人员假设，存在专门的适应寒冷的微生物，它们会产生甲烷，这是一种强有力的温室气体，这些微生物在大部分土柱处于冰点的这段时间里活动。研究人员还认为，每年从北极土壤排放到大气中的甲烷中，很大一部分可能是由这些专门的微生物造成的。这项研究将测试这种专门的冷适应甲烷产生微生物在这段时间内是否活跃，如果是，它们对每年土壤甲烷通量的贡献有多大。为了验证这一假设，这项研究将采用田间、实验室和计算机模型模拟。该项目旨在预测北极将如何应对当前和未来的气候变化，并为决策者提供更好的信息。该项目还将继续一个由阿拉斯加北坡和圣迭戈的当地社区和学生参与的精心开发的外展项目。通量塔的测量表明，在北极秋季，土壤剖面在零摄氏度时几乎是等温的，甲烷排放量稳定而显著。研究人员认为，这种秋季的通量是由专门的适应寒冷的产甲烷微生物群落维持的，这些微生物生活在土柱中。这项研究将测试这种适应寒冷的专门产甲烷群落在这段时间是否活跃，如果是的话，它们对每年土壤甲烷排放的贡献有多大。拟议的研究包括野外同位素工作、实验室孵化、甲烷通量监测和建模。这项工作的建模方面是作为对前一个小组建议的回应而添加的。

There is a long period during the Arctic fall, when much of the soil profile is suspended near 0°C. The investigators propose that this time of year may hold key information needed to better understand how Arctic ecosystems can be affected by climate change. The investigators hypothesize that there exist specialized cold-adapted microbes, which produce methane, a potent greenhouse gas, and that these microbes are active during this period when much of the soil column is at the freezing point. The investigators also argue that these specialized microbes may be responsible for a large fraction of the annual methane released from Arctic soils to the atmosphere. The study will test whether such specialized cold-adapted methane producing microbes are active during this period, and if so, how much they contribute to the annual soil flux of methane. To test this hypothesis, this study will bring to bear, field, laboratory, and computer model simulations.This project aims to predict how the Arctic will respond to current and future climate change, and to better inform decision makers. This project will also continue a well-developed outreach program involving local communities and students from the North Slope of Alaska and San Diego.Flux tower measurements have shown steady and significant methane emissions well into the Arctic fall, when the soil profile is nearly isothermal at zero degrees celsius. The investigators argue that this fall flux is maintained by specialized cold-adapted methanogenic microbial communities that live in the soil column. The study will test whether such specialized cold-adapted methanogenic communities are active during this period, and if so, how much they contribute to the annual soil efflux of methane. The proposed study includes field isotope work, laboratory incubations, methane flux monitoring, and modeling. The modeling aspect of the work was added as a response to suggestions from a previous panel.