4th UF Water Institute Symposium Abstract

Submitter's Name Jing Hu
Session Name Poster Session: Managing water for people and the environment
Poster Number 57
Author(s) Jing Hu,  University of Florida (Presenting Author)
  Kanika Inglett,  University of Florida
  Alan Wright, University of Florida
  Mark Clark, University of Florida
  Ramesh Reddy, University of Florida
  Influence of flooding and draining cycles on greenhouse gas emissions from peatlands
  Climate change has been predicted to cause changes in precipitation patterns, which directly affect the duration of flooding and draining cycles and hydrologic conditions of peatlands. Fluxes of greenhouse gases (GHGs), including carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O), from soils are affected by the frequency and duration of flood-drained cycles. Objectives of this study were to: (1) determine the different responses of CO2, CH4, and N2O fluxes to various combinations of flooding and draining duration; and (2) determine the total global warming potential (TGWP) of GHGs fluxes from soils. A laboratory study was performed using intact soil cores (40 cm in depth) collected from peatlands of the Everglades Agricultural Area (EAA) in south Florida. Soil cores were subjected to different duration of flood periods (1 cm water table above soil surface) and drained periods (30 cm water table below soil surface) alternately for 6 months. Four cyclic treatments were included in this study: short-term draining + short-term flooding (SS), short-term draining + long-term flooding (SL), long-term draining + short-term flooding (LS), and long-term draining + long-term flooding (LL). Short-term and long-term duration refer to 2 weeks and 4 weeks time periods. Two controls, one continuously flooded (F) and the other drained (D), were also included. The preliminary results showed that, for all treatments, CO2 fluxes during drained periods were much higher than during flood. Fluxes of CH4 and N2O did not vary between drained and flood periods but flux pulses were observed after re-flooding events for both CH4 and N2O. Throughout the study, the treatment with a longer total drained period had higher cumulative CO2 flux, whereas cumulative CH4 and N2O fluxes were higher in the treatment with higher frequency of flood-drained cycle. Carbon dioxide was the major contributor to TGWP irrespective of the treatments.