Biogenic gases in tropical floodplain river

Analysis of the distribution of biogenic gases in the floodplain of the Mog i-Guacu River (Sao Paulo, Brazil) enabled the establishment of a "redox hie rarchy", in which the main channel was the most oxidizing environment, foll owed by Diogo Lake, with Infernao Lake having the most reducing conditions of the subsystems evaluated. Diogo Lake exported about 853.4 g C.m(-2) year (-1), of which, 14.6% was generated from methanogenesis and 36.7% by aerobi c respiration. For Infernao Lake, these values were 2016 g C.m(-2) year(-1) , 1.8% and 41.5%, respectively. Carbon export by these systems was predomin antly in the form of CO2, which was responsible for the release of 728.78 g C.m(-2) year(-1) at Diogo Lake and 1979.72 g C.m(-2). year(-1) at Infernao Lake. Such patterns may result from the nature of the hydrological conditi ons, the action of the hydroperiod, and morphological characteristics of th e environment.