University thesis:
Dissertation, Universität Bremen, 2021
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Description:
Carbon dioxide (CO2) and methane (CH4) are the two most important anthropogenic greenhouse gases. Due to human influences, their concentrations in the atmosphere have increased over the past 150 years, causing increased warming of the Earth’s surface. For the global budgets of CO2 and CH4, it is not only important to assess anthropogenic emissions of CO2 and CH4 but also to understand the response of their natural fluxes to a changing climate. Wetlands are one of the world's largest carbon pools. While natural wetlands represent a CH4 source to the atmosphere, slow decomposition processes due to anaerobic conditions in their waterlogged soils lead to net carbon accumulation in wetlands. Especially peat soils, which consist of dead and decaying plant material, sequester large amounts of carbon from the atmosphere and, in their natural state, represent an atmospheric carbon sink. The objective of this study is to constrain carbon emissions from tropical wetland regions and to understand what drives these emissions. The study is structured into three major research topics. The first research topic focuses on tropical rivers that drain peatlands. It aims to explain moderate CO2 fluxes observed from peat-draining rivers and to improve CO2 emission estimates from these rivers. The second research topic aims to quantify the response of CO2 emissions from tropical peat regions to the application of enhanced weathering. To achieve this, the CO2 emission response from peat soils, peat-draining rivers, and coastal areas to enhanced weathering induced pH changes are derived based on a case study for Sumatra. The third research topic aims to constrain CH4 emissions from tropical wetland regions. For this, different emission datasets are evaluated by use of an atmospheric chemistry and transport model and satellite retrievals.