METHANE DISTRIBUTION AND PRODUCTION IN GEORGIA SALT-MARSH

Bacterial action in the anaerobic sediments of Spartina [S. alterniflora] salt marsh [in Georgia, USA] produce large quantities of CH4. Water in contact with the marsh has CH4 concentrations 200-300 times normal oceanic concentrations. The CH4 content of the water varies from a maximum of 1.2 .mu.l CH4 l-1 in the summer to a minimum of 0.005 .mu.l CH4 l-1 in the winter. CH4 production appears to be temperature dependent. CH4 content of the sediment generally increases with depth to maximum observed concentrations of 2.8 ml CH4 l-1 interstitial water. The flux of CH4 from the sediment is estimated by a variety of techniques to be about 0.21 ml CH4 m-2 h-1 (1 g CH4-C m-2 year-1). CH4 flux is higher in the high marsh than the low marsh.