Denitrification and a Nitrogen Budget of Created Riparian Wetlands
- Jacqulyn A. Batsonac,
- Ülo Manderb and
- William J. Mitsch *ad
- a Wilma H. Schiermeier Olentangy River Wetland Research Park, The Ohio State Univ., 352 W. Dodridge St., Columbus, OH 43202
c current address: U.S. Geological Survey, 12201 Sunrise Valley Dr., MS 430, Reston, VA 20192-0002
b Dep. of Geography, Institute of Ecology and Earth Sciences, Univ. of Tartu, Estonia
d current address: Everglades Wetland Research Park, 110 Kapnick Center, Florida Gulf Coast Univ., 4940 Bayshore Dr., Naples FL 34112. Assigned to Associate Editor Pierre-Andre Jacinthe
Riparian wetland creation and restoration have been proposed to mediate nitrate-nitrogen (NO3−–N) pollution from nonpoint agricultural runoff. Denitrification by anaerobic microbial communities in wetland soils is believed to be one of the main sinks for NO3−–N as it flows through wetlands. Denitrification rates were quantified using an in situ acetylene inhibition technique at 12 locations in three wetland/riverine sites at the Olentangy River Wetland Research Park, Columbus, Ohio for 1 yr. Sites included two created flow-through experimental wetlands and one bottomland forest/river-edge site. Points were spatially distributed at inflows, center, and outflows of the two wetlands to include permanently flooded open water, intermittently flooded transitions, and upland. Annual denitrification rates (median [mean]) were significantly higher (p < 0.001) in permanently flooded zones of the wetlands (266  μg N2O–N m−2 h−1) than in shallower transition zones (58 [37.5] μg N2O–N m−2 h−1). Median wetland transition zone denitrification rates did not differ significantly (p ≥ 0.05) from riverside or upland sites. Denitrification rates peaked in spring; for the months of April through June, median denitrification rates ranged from 240 to 1010 μg N2O–N m−2 h−1 in the permanently flooded zones. A N mass balance analysis showed that surface water flux of N was reduced by 57% as water flowed through the wetland, but only about 3.5% of the N inflow was permanently removed through denitrification. Most N was probably lost through groundwater seepage. Comparison with denitrification rates measured previously in these wetlands suggests that these rates have remained steady over the past 4 to 5 yr.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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