THE BIOGEOCHEMISTRY OF INTACT, DEGRADED, AND DEFORESTED IRISH BLANKET BOG

Peatlands are carbon-rich wetlands that account for ~3% of global land area and store ~30% of global soil carbon. These ecosystems are sensitive to water table fluctuations caused by seasonal rainfall and anthropogenic degradation. Anticipated temperature and precipitation changes may alter peatland biogeochemistry in ways that are not yet understood. To contextualize these processes, our research team is investigating the chemistry of a stream draining intact, degraded, and deforested Irish blanket bog subcatchments to characterize seasonal and event‒specific biogeochemical processes. Blanket bogs are a type of globally rare ombrotrophic peatland that account for one eighth of Ireland’s land area. We collected samples to quantify major ion, nutrient, dissolved organic carbon (DOC) fluxes, and to identify sources of dissolved constituents in the blanket bog system. Preliminary results from dry conditions in July 2022 showed surface water DOC concentrations were greatest in surface pools (>1300 μM) and lowest in the stream draining the forested bog subcatchment (<700 μM). Surface water inorganic N concentrations ranged from <1 to 14 μM for NO₂+NO₃ and <1 to 34 μM for N-NH₄. Soluble reactive phosphate concentrations were <1 μM at all stream and surface pool locations. The fluctuating inorganic N concentrations in the stream suggested a change in stream redox conditions, and increased concentrations of rock-derived chemical constituents, like Ca, Mg, H₄SiO₄, indicated greater contribution of groundwater mixing with peat porewater downstream. Samples collected from stream, surface waters, and peat porewaters in March 2023 provide context for nutrient and DOC cycling patterns in wet conditions. Data from these samples will also be used to calculate nutrient and DOC fluxes from the three subcatchments to identify source areas of dissolved nutrient and chemical export.