XVI International Botanical Congess

Methane d13C patterns vary between plants using convective throughflow ventilation relative to those which employ molecular diffusion. In diffusive plants, methane sampled from lacunal air was 13C-enriched by 10.6 ± 3.7 o/oo relative to sedimentary CH4. In plants possessing the convective flow system, differences between plant lacunal methane collected in daylight and sediment methane were not apparent, and averaged -0.9 ± 2.1 o/oo. At night, as convection gave way to molecular diffusion, the isotopic distributions in convective-flow plants became similar to distributions observed in diffusive plants. Methane concentrations within lacunal air also vary markedly between convective plants and diffusive plants and within convective plants on a diel basis.