Breathing in – breathing out: Scientists of TU Freiberg trace the Amazon rainforest’s respiration

Measuring robot on a lake in the Amazon region. Dark clouds in the background.
On March 3, a team of geoscientists at TU Bergakademie Freiberg will travel to Manaus carrying with them a 120 centimetres long measuring device. With the newly developed robot they aim to analyse the gas exchange of carbon dioxide of 13 lakes and ponds in the Amazon Basin.

Back in their laboratory, they will also identify the gas flow of methane and nitrous oxide. Having travelled to Manaus in October 2021 during the dry season, the team will now study the same waters again during the rainy season.

"The gas exchange of the waters we visited appears representative of standing bodies of water typical in the Amazon basin in the dry season," says project leader Prof. Jörg Matschullat of TU Bergakademie Freiberg. There is a difference of up to 30 meters between the minimum water level of the dry season and the maximum water level of the rainy season. If the level rises or falls, the pressure of the water column on the soil changes, its ability to store carbon is affected and climate-relevant gases can be released. That is why, in March 2022, the researchers will study the same waters again during the rainy season. "We are particularly interested in what effects the water level fluctuations have on gas exchange, because this can serve as a model for extreme weather conditions in Europe, as well," explains Prof. Jörg Matschullat.

Forests awash: Understanding tropical waters

Once the results from the comparison of soil respiration in the dry and rainy seasons are available, the team will be able to draw important conclusions for existing climate models in the Amazon region: "Understanding and correctly determining the storage, sink and source functions of tropical waters is an essential prerequisite for targeted water management - also in terms of adaptation to climate change," explains the Freiberg geoecologist. "Thanks to the new findings, however, we also expect answers to the question of what future climate realities might look like," says Prof. Matschullat. "Studies under tropical and seasonally changing climate conditions are extremely helpful in order to better assess future behavior of the environmental system and to respond to it."

Newly developed measuring device acquires and visualizes data
The scientists obtained the data on the Amazon's respiration using a newly developed measuring platform attached to a measuring robot. "The platform is also equipped with several sensors that can simultaneously record other water parameters at different depths. In addition, a sonar detects underwater structures; other sensors detect obstacles in and on the water body, thus laying the foundation for the automatic path planning of the measurement system," Prof. Yvonne Joseph from the Institute of Electronic and Sensor Materials explains.

During the measuring campaigns in Brazil, the scientists are testing how effectively the measuring robot can collect data under humid tropical conditions. "In order to prepare the robot for an autonomous operation, initial technical tests of the robot's localization by satellite navigation in the Amazon's maze of trees as well as the quality of the depth measurement have now been run. What’s more, the warm, humid climate places its own demands on the installation and electronics of the system," reports Prof. Sebastian Zug of the Chair of Software Technology and Robotics of TU Bergakademie Freiberg. In the future, the measuring robot will be able to travel autonomously even under challenging conditions and collect data either in the area or at specific points. "Depending on the scientific scope, the data can then be used to derive a two- or three-dimensional model of the water body and the environment under and above water, which can be visualized and analysed in virtual reality applications," says Prof. Zug.

Background information

Research project within EU-funded junior research group
The project is included in the interdisciplinary research group Robot-assisted inland water monitoring supported by the German Federal State of Saxony with resources from the European Social Fund until the end of December 2022.

The research project aims to investigate the exchange behavior of greenhouse gases from tropical lakes over a period of three years in several measurement campaigns. The two research trips of the Freiberg team are supported by the German Federal Ministry of Education and Research and the German Federal Environmental Foundation. On site, the researchers are collaborating with the Brazilian research institution EMBRAPA Amazonas Ocidental. EMBRAPA is contributing local infrastructure and logistics to the project. The measuring technology that is being developed could later on be used by Brazilian authorities for water and wetland monitoring.

Fragen beantwortet / Contact: 
Prof. Dr. rer. nat. habil. Jörg Matschullat, joerg.matschullat@ioez.tu-freiberg.de