What is RoBiMo-Trop?
Building on the RoBiMo project (Robotic Inland Waters Monitoring), which has been running since January 2020, the subsidiary project RoBiMo-Trop, which started in August 2021, is dedicated to studying tropical waters. Within the framework of five field campaigns and in close cooperation with the Brazilian research authority Embrapa, lakes in the Brazilian Amazon basin are visited for measurements of greenhouse gas exchange. The project is funded by the International Bureau of the Federal Ministry of Education and Research (BMBF) from 01.08.2021 to 31.12.2022, and by the Deutsche Bundesstiftung Umwelt (DBU) from 01.03.2022 to 31.08.2023.
Photo: Tropical primary forest environment (Reserva Ducke), 1st field campaign (MUSA)
Motivation and project description
The aim of RoBiMo-Trop is a) to put the technology to be developed in the RoBiMo project through its paces under the harsh conditions of the inner humid tropics and thus arrive at maximally robust and reliable technical solutions (part BMBF), and b) to sample tropical stillwaters of various types in order to record and quantify their source or sink function for carbon and nitrogen. The overall aim is to obtain more sustainable solutions for agriculture and to contribute to a better understanding of global material cycles (Part DBU). Water origin (clear water, black water and white water lakes) as well as trophic level (eutrophic, meso and oligotrophic) and lake type (artificial reservoirs, aquaculture and natural flood lakes) are taken into account.
Temporarily flooded ecosystems have become the focus of climatological studies in recent years due to their intensive exchange of the greenhouse gases carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O) with the atmosphere. Given the high speed and intensity of mass transfer processes and partly high temporal and spatial dynamics of water level changes, water bodies in the tropics are good research objects to better understand processes and feedbacks relevant for gas exchange. Since, in the medium term, a year-round warming of water temperatures of surface waters and strong water-level fluctuations can be assumed in temperate latitudes as result of climate change, findings from studies in tropical areas can provide valuable information on the future behaviour of water bodies in a temperate climate.
Photo 1: Balbina reservoir with Prof. Maximilian Lau and MSc Eric Röder. Photo 2: Fish farm near Rio Preto da Eva with Eric Röder. 1st field campaign with the platform in gas exchange mode. Photo 3: Measuring platform on a clearwater lake with heavy rain. Photo 4: MSc Eric Röder with multiparameter probe on a whitewater lake; both 1st campaign.
Technical development and applications in field campaigns
RoBiMo-Trop, like RoBiMo, follows the holistic approach to realise the measurement of greenhouse gas exchange in combination with sampling of the water column (in situ measurement with multiparameter probe as well as water sampling) and the sediment (sampling for subsequent determination of carbon and nitrogen stocks). For this purpose, the project offers the possibility to test the technology developed within the framework of RoBiMo for robustness and functionality under extreme temperature and humidity conditions.
The first field campaign in the Amazon basin was successfully carried out in September 2021 (dry season; news article on RoBiMo-Trop). During the two-week campaign, a version of the CO2-measuring bell (SEMACH-FGaqua), constructed at the TU Bergakademie Freiberg, was used for the first time for application in aquatic ecosystems. A total of 13 water bodies in the vicinity of Manaus were visited for the measurements: one clear water lake (Balbina reservoir), eight aquaculture ponds, two black water lakes and two white water lakes. At selected water bodies, it was also possible to test a measuring unit for position recording using GPS. Sending and receiving GPS data can be a challenge in temporarily flooded forest areas with dense canopies, but it provides a basis for the intended autonomous operation of the measuring platform.
The second campaign followed in March 2022 (rainy season) on five lakes (the same as before except for the pisciculture ponds). The modified chamber mechanism proved itself; even with stronger wind pressure or waves, air was no longer sucked in. Three Master's students (Leonore Dobrovsky, Oriana Blandón Pulido and Seán Adam) and PhD student Otto Dreier accompanied Prof. Jörg Matschullat. Photojournalist Eckardt Mildner accompanied the project and ensured remarkable press coverage. The new sensor node (miniaturised multi-parameter probe) for simultaneous recording of autonomous real-time signals of hydrographic profiles (pH, T, rH, EC, O2, NTU, etc.) at all depths has to be further modified; in each case, water penetrated the measuring chamber after a few metres of immersion. Currently, the data collected is being evaluated and the samples brought in are being analysed.
The third campaign will again take place in the dry season in September 2022. Planning for this has begun.
Prof. Dr. rer. nat. habil. Jörg Matschullat
Chairing Professor for Geochemistry and Geoecology
Director of Interdisciplinary Environmental Research Centre
Address: Werner-Bau, Brennhausgasse 14, Room 36
Phone: +49 3731 39-3399
Mail: joerg [dot] matschullatioez [dot] tu-freiberg [dot] de