Hydrogen isotopes in lignin: a new proxy for the Amazon hydrological cycle?
Lead Research Organisation:
University of Leeds
Department Name: Sch of Geography
Abstract
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.
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.
Publications
GuimarĂ£es K
(2024)
Intra-annual stable isotopes in the tree rings of Hymenaea courbaril as a proxy for hydroclimate variations in southern Amazonia
in Dendrochronologia
| Description | We are unfortunately delayed in our project mainly due to a significant delay in isotope analysis by the Stable isotope laboratory by the university of Leicester. Over the summer, of 2024, Co-I Boom has made significant progress with the methodology that we said we would develop and has successfully created a fully automated method on the GC-IsoLink to measure methyl iodide hydrogen isotopes. According to our schedule Boom was going to analyse the samples after he returned from annual leave but during his annual leave the University of Leicester announced that the Bennett Building in which the laboratory is housed will be closed for a period of two years due to structural failings and safety. Fortunately, it is expected that Dr. Boom can get limited access to the original laboratory this spring and he will then prioritise the measurements of the methyl iodide for this project. While we have made progress and succeeded with the development of the analytical procedure we do currently not have any new measurement data we can share. |
| Exploitation Route | not yet |
| Sectors | Environment |