Hydrogen isotopes in lignin: a new proxy for the Amazon hydrological cycle?

木质素中的氢同位素：亚马逊水文循环的新代理？

• 批准号: NE/X012921/1
• 负责人: Roel Brienen
• 金额: $ 10.3万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2022
• 资助国家: 英国
• 起止时间: 2022 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FX012921%2F1
• 关键词: Hydrogen; isotopes; lignin; new; proxy

The Amazon basin is the world's largest catchment and sustains the largest continuous rainforest on Earth. Global change is affecting the Amazon climate in uncertain ways, with recent decades seeing an increase in Amazon wet season rainfall, as well as, increasing drought frequency. To better understand the drivers behind these changes, long-term accurate records of the hydrological cycle are needed. In this project we will test a new climate proxy derived from hydrogen isotopes in tree rings that can contribute towards such reconstructions. In contrast to existing oxygen isotope proxies in the Amazon, hydrogen isotopes in lignin methoxyl groups are thought to preserve the signal of hydrogen isotopes in precipitation. We will test to what degree hydrogen isotopes growing along an elevational transect from the Amazon to the Andes indeed preserve variation in hydrogen in precipitation, and apply this new method for the tropical tree species Cedrela odorata at a dry and wet site to reconstruct precipitation oxygen isotopes for the past 50 to 150 years at annual resolution. If successful this new proxy can be used to generate insights in the response of the tropical hydrological to climate change. Reconstructions of hydrogen isotopes in the source water can further be useful to interpret long-term change in plant physiology to CO2 when used in combination with oxygen and carbon isotopes from tree rings.

亚马逊盆地是世界上最大的集水区，维持地球上最大的连续雨林。全球变化以不确定的方式影响了亚马逊气候，最近几十年的降雨量增加，并且干旱频率的增加。为了更好地了解这些变化背后的驱动因素，需要长期准确的水文周期记录。在这个项目中，我们将测试从树环中氢同位素衍生出的新气候代理，可以有助于这种重建。与亚马逊中现有的氧同位素代理相反，木质素甲氧基的氢同位素被认为可以保留沉淀中氢同位素的信号。我们将测试沿着从亚马逊到安第斯山脉的高程横切的氢同位素在降水中确​​实保留了氢的变化，并将这种新方法应用于热带树种在干燥和湿地的热带树种Cedrela odorata，以在过去的50至150年中以干燥和潮湿的位点重建降水氧同位素。如果成功，则可以使用这种新代理来在热带水文对气候变化的反应中产生见解。当与树环的氧和氧和碳同位素结合使用时，源水中氢同位素的重建对于解释植物生理的长期变化可能会进一步有用。