Date of Award
Master of Science
Ecology, Evolution, and Organismal Biology
William G. Crumpton
Nitrate loads from agricultural sources raise major water quality concerns for the US Corn Belt. Wetland restoration has been identified as a promising strategy to reduce nonpoint source nitrogen loads from agricultural watersheds. However, there is concern over increased nitrous oxide (N2O) emissions from wetlands subject to elevated nitrogen loads. The major purpose of this research was to quantify N2O and CH4 emissions from wetlands targeted to intercept and reduce nitrate loads in agricultural watersheds. We measured nitrate removal and N2O and CH4 emission rates at three wetlands subject to different nitrate loads. Nitrate loads and losses were estimated based on close interval monitoring of inflows and outflows. N2O and CH4 emissions were estimated using floating chambers during synoptic studies conducted from late spring through early fall in 2015-2016. N2O emission rates averaged 3.5 mg N2O-N m-2 day-1, similar to rates from cropland even though wetlands received more N per area than croplands. N2O emission rates were correlated to nitrate concentrations, loading rates, and loss rates. CH4 emission rates averaged 793 mg CH4 m-2 day-1, similar to rates for restored depressional wetlands in Iowa.
Hannah Leigh Hoglund
Hoglund, Hannah Leigh, "Greenhouse gas emissions from Iowa Conservation Reserve Enhancement Program wetlands" (2017). Graduate Theses and Dissertations. 16145.