Studying the carbon balance of the Amazon by measuring the 17O anomaly of CO2

Getachew A. Adnew

The Amazon is a major player in the global carbon cycle. Recent measurements showed a widespread loss of carbon from the terrestrial biosphere there during severe droughts, which suggests a large sensitivity of the Amazon carbon balance to a more intense drought regime in the next decades. However, there is no scientific consensus on the most basic metrics of Amazonian carbon exchange: the gross primary production (GPP) and its response to moisture deficits in the soil and atmosphere.

The goal of this project is to develop a new isotope tool for determining the GPP of the Amazon. We will use the 17O isotope anomaly in CO2, which is affected by the interaction of CO2 with leaf water in plant stomata. Hence, the isotope signal depends directly on the magnitude of GPP. The challenge is to measure the 17O isotope anomaly with high precision because the expected signal is small. In the project we will set up the analytical technique and carry out a large number of measurements on air samples from an established aircraft monitoring program in Brazil.