Methane flux from Missippi River deltaic plain wetlands

Methane emissions from three wetland habitats in the MississippiRiver deltaic plain were measured over a three year period. Fluxdata collected indicate that each habitat was a net source of methane to the atmosphere throughout the year. Average emissionfrom a Taxodium distichum / Nyssa aquatica (bald cypress / watertupelo) swamp forest was 146 ± 199 mgCH₄ m^-2d^-1 whileemissions from a Sagittaria lancifolia (bulltongue) freshwatermarsh averaged 251 ± 188 mg CH₄m^-2d^-1. Methane flux from a Spartina patens / Sagittaria lancifolia intermediate marsh was significantlyhigher, 912 ± 923 mg CH₄m^-2d^-1. Seasonal variation wassignificant with emissions being higher in the late summer andearly fall. Significant diurnal emissions were observed fromthe Sagittaria lancifolia marsh site. Soil temperature (5 and 10 cm depths) was found to be significantly correlated with methaneemission from the three sites.