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UP: Fachverband Umweltphysik

UP 6: Atmospheric Chemistry 2

UP 6.2: Vortrag

Mittwoch, 18. März 2020, 16:50–17:10, HSZ 105

Southeast Asian river CO2 emissions regulated by water pH — •Alexandra Klemme¹, Denise Müller-Dum¹, Moritz Müller², Justus Notholt¹, Tim Rixen³, and Thorsten Warneke¹ — ¹Institute of Environmental Physics (IUP), Bremen, Germany — ²Swinburne University of Technology, Faculty of Engineering, Computing Science, Kuching, Sarawak, Malaysia — ³Leibniz Center for Tropical Marine Research (ZMT), Bremen, Germany

Southeast Asian rivers have been recognized as a hotspot for carbon dioxide (CO2) outgassing. This is due to extensive peatlands in Southeast Asia, which represent a globally important carbon store that is destabilized by deforestation, drainage and conversion into plantations. Peatland degradation is assumed to have increased carbon leaching from peat soils by about 200%. Despite the enhanced mobilization of carbon, recent data based estimates suggest only moderate CO2 emissions from Southeast Asian rivers. We find that the cause for these limited CO2 emissions is the water pH, which decreases along with increasing dissolved organic carbon (DOC) concentrations and hampers DOC respiration. Inputs of carbonate derived from rock weathering and soil erosion upstream of the coastal peatlands can suspend these natural limits by rising the pH. This implies that deforestation in the hinterland but also liming, which is a common practice in e.g. palm oil plantations, could increase CO2 outgassing from peat draining rivers. Furthermore, the pH dependency needs to be considered with regard to enhanced weathering, which is discussed as a possible measure to bind atmospheric CO2 and would increase soil and water pH.