Exploring Dissolved Organic Carbon Variations in a High Elevation Tropical Peatland Ecosystem: Cerro de la Muerte, Costa Rica

RICARDO, SÁNCHEZ-MURILLO; PAOLA, GASTEZZI-ARIAS; ROLANDO, SÁNCHEZ-GUTIÉRREZ; GERMAIN, ESQUIVEL-HERNÁNDEZ; ROY, PÉREZ-SALAZAR; MARÍA, POCA

Frontiers in Water

FrontiersIn

Lugar: Lausanne; Año: 2022 vol. 3

Tropical peatlands are distributed mainly in coastal lowlands; however high elevationregions exhibit a large prevalence of small and fragmented peatlands that are mostlyunderstudied. Artificial drainage of peatlands to expand the area of cattle farming,horticulture, and urbanization is increasing carbon losses to the atmosphere andstreams worldwide. Here, we present an exploratory characterization of dissolved carbonoptical properties in ombrotrophic peat bogs of the Talamanca range of Costa Rica,across an altitudinal gradient (2,400?3,100m a.s.l.) during the rainy season. Dissolvedorganic matter (DOM) sources and decomposition processes were evaluated in thelight of dissolved organic and inorganic carbon (DOC and DIC), optical properties, andmajor water chemistry. DOC concentrations ranged from 0.2 up to 47.0 mg/L. DICconcentrations were below 2 mg/L and d13CDIC values indicated a mixture between soilorganic matter, CO2 in soil water, and to a lesser degree DIC derived from bacterialCO2. Absolute fluorescence intensity of humic-like peaks was 6?7 times greater thanfresh-like peaks across all sites. Fluorescence peak ratios coupled with the biologicaland humification indexes point to a greater relative contribution of recalcitrant soil-derivedDOM. Excitation/Emission matrices denoted a high prevalence of humic and fulvic acidsin the peat bogs, with moderate intensities in soluble microbial by-products-like andaromatic protein regions at three sites. Our data provides a baseline to underpin tropicalcarbon dynamics across high elevation peatlands.