Coastal Ecosystems: Climate Change and Anthropogenic Impacts

盐沼，被海潮淹没的草甸，是特殊的碳汇，因为它们的植被固定了大气中的二氧化碳，并将其储存在土壤中数千年。我的研究项目将量化加拿大两个盐沼的碳汇规模。与此同时，我将研究甲烷和一氧化二氮的潜在排放，这两种温室气体可以从沼泽排放出来。这些气体的排放抵消了储存碳的价值，因为就全球变暖而言，它们比二氧化碳更有效。通过比较碳储量和温室气体排放量的比率，我们可以评估盐沼的潜在气候反馈，以及它们在过去或未来的损失如何影响气候。正在进行的湿地施肥实验将被纳入这项研究，以确定释放到沿海土地和水域的过量营养物质将如何影响气体排放，从而影响气候反馈。这项研究将对保护具有直接价值，因为它将使我们能够估计防止盐沼损失或恢复沼泽在碳储存及其气候影响方面的价值。事实上，储存在盐沼中的碳被称为“蓝碳”，现在正被考虑用于碳抵消计划，期望出售蓝碳信用额度将刺激沿海沼泽的保护和保护。然而，我们还没有准确地记录整个沼泽中储存的碳的数量或速率。我们也没有对可能降低碳经济价值的温室气体排放潜力进行全面评估。我的研究试图通过回答以下问题来填补这一空白：1)沼泽中的碳储量和储存率如何变化；什么是控制因素，什么是存储的最佳预测因素？3)温室气体排放变化有多大，控制因素是什么，哪些变量是这些排放率的最佳预测指标？4)养分富集如何影响贮藏潜力和气体排放？这些问题的答案对沿海管理的规划也很有价值。

Salt marshes, grassy meadows flooded by ocean tides, are exceptional carbon sinks as their vegetation fixes carbon dioxide from the atmosphere and stores it in the soil for millennia. My research program will quantify the magnitude of this sink in two Canadian salt marshes. At the same time I will examine the potential for emissions of methane and nitrous oxide, two greenhouse gases that can be emitted from marshes. Emissions of these gases counter the value of stored carbon as they are more potent than carbon dioxide in terms of global warming. By comparing the rates of carbon stored and greenhouse gases emitted we can assess the potential climate feedbacks of salt marshes and how their loss in the past, or future, might affect climate. Ongoing experiments of fertilized marshes will be incorporated into this study to see determine how excess nutrients released to coastal lands and waters will affect gas emissions, thus climate feedbacks. This research will have immediate value to conservation because it will enable us to estimate the value of preventing salt marsh loss or restoring marshes in terms of carbon storage and its climate ramifications. In fact, the carbon stored in salt marshes, called "Blue Carbon", is now being considered for carbon offset programs with expectation that sale of Blue Carbon credits will stimulate preservation and conservation of coastal marshes. However, we have yet to accurately document the amount the amount or rate of carbon stored within an entire marsh. Neither have we performed a comprehensive assessment of the potential for greenhouse gas emissions that could reduce the economic value of the carbon. My research seeks to fill this void by answering the following questions: 1) How do carbon stocks and storage rates vary within a marsh; what are the controls, and what are best predictors of the storage? 3) How much do greenhouse gas emissions vary, what are the controls, and what variables are best predictors of those rates? 4) How does nutrient enrichment affect the storage potential and gas emissions? Answers to these questions will be valuable to planning for coastal management as well.