BOOK OF ABSTRACTS 207 IHSS&IWA26 / BRNO / CZECHIA / 23–28 August 2026 Hall A Poster Session / Soil Organic Matter, Caustobiolites, and Biochar P2.12 Linking Soil, Hydrology and Aquatic Carbon Dynamics: How Mineral Cover Depth Modulates Greenhouse Gas Emissions in Subtropical Agricultural Peatlands Shan-Li Wang1, Cheng-Chun He2, Po-Neng Chiang3, Yuh-Rong Guh4 1 Department of Agricultural Chemistry, College of Bioresources and Agriculture, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei City 10617, Taiwan, ROC; wangsl@ntu.edu.tw 2 Agricultural Net-Zero Carbon Technology and Management Innovation Research Center, College of Bioresources and Agriculture, National Taiwan University, Taipei City 10617, Taiwan, ROC 3 The Experimental Forest, College of Bio-Resources and Agriculture, National Taiwan University, Nantou County, Taiwan, ROC 4 Water Resource Planning Branch, Water Resources Agency, Ministry of Economic Affairs, Taichung City 413, Taiwan, ROC Peatlands store roughly one-third of the global soil organic carbon pool [1]. Driven by agricultural demand, artificial drainage and land development have disrupted this soil–water coupling, turning peatlands into major sources of greenhouse gases (GHGs) [2]. In subtropical Taiwan, the Toushe Basin peatland (~150 ha) has been extensively converted to upland loofah (Luffa cylindrica) cultivation and overlain by mineral soil of variable thickness; the effect of this overlay on soil–water– atmosphere fluxes and aquatic carbon cycling remains unresolved. Across 11 sites grouped into four cover-depth classes (none, thin <30 cm, medium 30–70 cm, thick >100 cm), we integrated soil profile characterization (0–100 cm; pH, bulk density, total carbon, C/N), closed-chamber GHG flux measurements (Li-7810 / Li-7820), and continuous groundwater-level monitoring (n = 253 paired observations) to bridge soil, hydrology, and aquatic biogeochemistry; Spearman and partial correlation analyses were applied to disentangle the interactions among water-table dynamics, temperature, and cover depth [3]. CH4 emissions occurred exclusively in uncovered peat, where the saturated matrix remained hydrologically and biogeochemically continuous with the underlying aquifer; CH4 correlated strongly with water-table height (ρ = 0.68, p < 0.001) and was ~6-fold higher during high-water periods. CO2 rose under medium-to-thick cover, reflecting aerobic oxidation of exposed peat humic carbon and amplified sensitivity to water-table fluctuations (ρ = 0.34–0.43). Thin cover (<30 cm) showed the lowest 100-year global warming potential (CO2 + 27 × CH4) [4] and was the only category statistically decoupled from both drivers. Partial
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