ABSTRACT
This chapter discusses the application of oxygen electrodes to determine rates of oxygen and consumption in wetland ecosystems. Depending on the hydrologic connectivity and regime and hydroperiod, wetland soils often alternate between drained and flooded soil conditions. Gas exchange between the atmosphere and soils is regulated by the hydrologic connectivity through surface and groundwaters and water table depth. The most important biogeochemical reactions involving gases include microbial and plant respiration that consume oxygen and produce carbon dioxide. Under flooded or saturated soil conditions, emergent aquatic vegetation develop physiological adaptations and transport oxygen through aerenchyma tissue into the root zone to support root respiration. Respiration by biota in the soil water column consumes oxygen and produces carbon dioxide during both night and day. In many wetlands and aquatic ecosystems, daytime oxygen production typically exceeds oxygen consumption. Depending on the hydroperiod and hydrologic connectivity, the water table in wetlands can fluctuate and at times leave the upper portion of the soil unsaturated.
