Studying dissolved organic carbon in tropical rivers of Malaysia using in-situ and satellite observations

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Climate is intimately linked to the concentration of the greenhouse gas carbon dioxide (CO2) in the atmosphere. A priority amongst scientists worldwide is therefore to quantify fluxes of carbon within the Earth system, and to understand how mankind is altering these fluxes. Researchers have assessed terrestrial biomes (i.e. tropical forests, temperate forests, and boreal peatlands) as well as aquatic ecosystems (i.e. lakes and oceans), however very seldom connected both biomes or studied the pathway between the two, i.e. rivers. While peatlands only cover approximately 3% of Earth’s land area, they store a significant amount of carbon, and play an important role in the global carbon cycle. In the tropics, peat swamp forests and the underlying peat deposits constitute one of the largest near-surface reservoirs of organic carbon. South-East Asian peats contain ~70 Gt C, mostly on Sumatra and Borneo. The rivers draining these peatlands are very rich in DOC derived from peat: Indonesia alone may account for 10% of the global DOC flux, but this estimate is based on data from only two rivers. In South-East Asia, the land-to-ocean DOC flux may also have risen significantly following the recent conversion of peatlands for agriculture, but owing to the paucity of data here, this has not yet been properly confirmed. Both collaborators have pioneered studies on the release of greenhouse gases from peat-draining rivers in Borneo over the past 4 years. The proposed project will focus on establishing long-term measurements of dissolved organic carbon to quantify annual variations of DOC transport in a representative peat draining river in a region where many peatlands are being converted to agricultural lands. In an extension and complimentary to our ongoing work, we will include satellite remote sensing data to estimate the concentration of soil-derived organic carbon in larger coastal seas to cover the whole of Borneo. The proposed project involves two short visits by A/P Müller to the University of Bremen to install in-situ logger and analyse field data collected in autumn 2017 (WP1) and comparing it to satellite data at the University of Bremen (WP2). Following the first visit, two field expeditions will be conducted in Malaysia (before and after the next north-east monsoon in October 2018 and March 2019), followed by a second short visit by A/P Müller to the University of Bremen to consolidate collected data, finalise manuscript for publication, and discuss long-term continuation in person (WP3).