PROCESSES AND MECHANISMS CONTROLLING CONSUMPTION OF CFC-11 AND CFC-12BY PEAT FROM A CONIFER-SWAMP AND BLACK SPRUCE-TAMARACK BOG IN NEW-YORK-STATE

We evaluated the potential consumption of chlorofluorocarbons CFC-11 a nd CFC-12 by pear soil from a conifer swamp and a temperate bog in New Yark Stare in order to assess whether extensive northern peatlands mi ght serve as a sink for atmospheric CFCs. Intact peat cores maintained with an anoxic headspace over the peat surface consumed CFC-11 and mi nor amounts of CFC-12 The consumption of CFC-11 showed a first-order r ate constant of 0.122 d(-1); hence, molecular diffusion transports CFC s through vegetation to consumption sites in the peat. Peat samples fr om the 0-10 cm depth in the swamp site showed higher microbial activit y and consumed both CFC-11 and CFC-12 at higher rates than deeper pear samples (20-30 cm depth). Conversely, deeper peat from the bog showed higher consumption rates for CFCs than pear samples from the 0-10 cm depth corresponding to the higher microbial activity deep in the pear profile. For both CFCs, consumption by incubated pear samples followed the series: anoxic > anoxic with carbon added much greater than, auto claved > oxic;anoxic methanogen inhibited > oxic with CH4. The results suggest that anaerobic sail in northern peatlands have the capacity t o serve as a sink for atmospheric CFCs.