| Abstract: | A portable gas chromatograph was employed in the Vestfold Hills, Antarctica, during the austral summer of 1979-80 for determining nitrogenase activity of the blue-green alga Nostoc commune Vaucher by the acetylene reduction assay. Acetylene reduction was measured in samples taken along a transect where the vegetation changed with respect to differing topography and water availability. Submerged colonies of Nostoc recorded the highest fixation rates (6.89 nmol C2H4. cm-2 h-1). Damp mosscyanophyte associations growing on shallow slopes showed moderate rates of acetylene reduction (1.99 nmol C2H4. cm-2 h-1) whilst the drier vegetation of the steeper terrain was the least active (0.19 nmol C2H4. cm-2 h-1. The employment of a high sensitivity portable gas chromatograph provided an accurate and reliable method of measuring acetylene reduction. |
