Processes and mechanisms controlling consumption of CFC-11 and CFC-12 by peat from a conifer-swamp and black spruce-tamarack bog in New York State

We evaluated the potential consumption of chlorofluorocarbons CFC-11 and CFC-12 by peat soil from a conifer swamp and a temperate bog in New York State in order to assess whether extensive northern peatlands might serve as a sink for atmospheric CFCs. Intact peat cores maintained with an anoxic headspace over the peat surface consumed CFC-11 and minor amounts of CFC-12. The consumption of CFC-11 showed a first-order rate constant of 0.122 d−1; hence, molecular diffusion transports CFCs through vegetation to consumption sites in the peat. Peat samples from the 0–10 cm depth in the swamp site showed higher microbial activity and consumed both CFC-11 and CFC-12 at higher rates than deeper peat samples (20–30 cm depth). Conversely, deeper peat from the bog showed higher consumption rates for CFCs than peat samples from the 0–10 cm depth corresponding to the higher microbial activity deep in the peat profile. For both CFCs, consumption by incubated peat samples followed the series: anoxic> anoxic with carbon added autoclaved> OXIC = anoxic methanogen inhibited> oxic with CH4. The results suggest that anaerobic soil in northern peatlands have the capacity to serve as a sink for atmospheric CFCs.