Detecting hydrological and carbon-cycle change in high-latitude environments with compound-specific isotope analyses

地球上北极和亚北极地区的变暖速度比地球上其他地区快，这种气候变化可能会强烈影响这些地区的水资源，以及它们产生的天然碳温室气体排放量（如二氧化碳和甲烷）。然而，气候变化对北极地区水和碳循环的影响尚不清楚。拟议中的研究将通过研究北极环境在过去温暖气候时期的变化，以及收集关于今天水和碳如何在北极环境中移动的详细信息，寻求更好地了解北极环境变化的这些方面。这项研究是通过分析在湖泊沉积物中发现的单个有机分子中稀有同位素或比正常质量稍重的原子的自然丰度来进行的。当水或碳在不同的环境之间移动时，它们的同位素丰度会发生变化，因此，同位素测量可以提供环境变化的记录。这项研究将侧重于分析不同生物产生的单个有机分子中的同位素比率，这是一种新的方法，可以避免与其他同位素分析相关的不确定性。这项研究将有助于解决的具体问题包括：1)当气温变暖或变冷时，加拿大东北部的降雨量和湖泊水位是如何变化的；2)当碳从土壤转移到湖泊时会发生什么，它能长期储存在湖泊沉积物中吗？3)是什么控制着湖泊中产生了多少甲烷，又有多少甲烷逃逸到大气中。

Arctic and Subarctic regions of the Earth are warming faster than the rest of the planet, and this climate change will probably strongly affect water resources in these regions, as well as the amount of natural carbon greenhouse gas emissions (e.g. carbon dioxide and methane) they produce. However, the effects of climate change on water and carbon cycling in Arctic regions are not well understood. The proposed research will seek to gain a better understanding of these aspects of Arctic environmental change, both by studying how Arctic environments changed during past periods with warm climates, and by gathering detailed information about how water and carbon move through Arctic environments today. This research is performed by analyzing the natural abundance of rare isotopes, or atoms with slightly heavier-than-normal masses, in individual organic molecules found in lake sediments. When water or carbon moves between different environments the abundance of their isotopes changes, and because of this, isotope measurements can provide a record of environmental change. This research will focus on analyzing isotope ratios in individual organic molecules produced by different organisms, a novel approach that will avoid uncertainties associated with other isotope analyses. Specific questions this research will help address include: 1) How did rainfall and lake levels change in Northeastern Canada when temperatures became warmer or cooler; 2) What happens to carbon when it moves from soils to lakes, and can it be stored in lake sediments for long periods of time; 3) What controls how much methane is produced in lakes, and how much of that methane escapes to the atmosphere. This research is important because it will provide new data on how Arctic ecosystems responded to climate change in the past, and will help to predict how these ecosystems could change in the future. This is necessary for climate scientists and policymakers who need to understand how different parts of the world will respond to global warming. This research is also important to Canadians who live in northern regions, since it can help to explain the dramatic changes that are occurring in their home. This research will benefit Canadians by giving a clearer picture of both the future of water resources in northern regions and the risk that northern environments will begin to emit more greenhouse gases as the climate warms.