Masterarbeit
Hydrology, Temperature, and the Atmospheric Tide as Controlling Factors of Methane Dynamics at a Tropical Palm Swamp
Toni Schott (01/2025-09/2025)
Betreuer: Christoph Thomas
Tropical wetlands are among the largest natural sources of atmospheric methane (CH4), yet their contribution to the global CH4 budget remains to a large degree uncertain. This is due to scarce monitoring in the tropics and limited understanding of environmental controls in these systems. This study addresses this gap by analysing one year of high-resolution CH4 concentration data from a seasonally flooded palm swamp in the Peruvian rainforest. Comparison with the surrounding forest highlights the relevance of wetlands in revealing methane dynamics. This study used 12 months of data from a novel monitoring setup with a multi-inlet gas sampling system. Diurnal and seasonal CH4 dynamics, as well as potential environmental drivers, were investigated. The results show that the palm swamp consistently exhibited higher CH4 concentrations throughout the year compared to the forest. Ebullition events, detected using a spike detection algorithm, followed a distinct semi-diurnal cycle, with a major peak during the afternoon. This peak was strongly correlated with rising temperature and atmospheric pressure perturbations, suggesting a cumulative effect of increased methanogenic activity, reduced CH4 solubility, and pressure release from the sediment. Soil hydrological conditions play a central role in controlling CH4 concentration patterns on a seasonal scale. When water levels were below the soil surface, CH4 concentrations increased with soil water content, indicating a waterlimited system. However, when the water table was above the soil, an increase in hydrostatic pressure due to an increase in the height of the water table led to a reduction in ebullition events and an overall reduction in CH₄ concentration. This study demonstrates the strength of high-resolution and long-term monitoring for revealing patterns and identifying drivers of CH4 dynamics in tropical wetlands.