Brian Grebulinas

Ph.D. Candidate, Illinois State University

Conference Travel Grant Type 2 (North American Benthological Society)

Enhancing Denitrification in Constructed Wetlands Through Manipulation of Nutrient Stoichiometry

“Agricultural tile drains transmit water laden with heavy nitrate (NO3-N) loads and relatively lower levels of phosphorus (PO4-P) and carbon (C). Reducing nitrate loading to streams using wetlands may be limited by tile water stoichiometry. We examined how nutrient stoichiometry of tile drainage affects denitrification rates. If successful this may provide a new method for enhancing wetland efficiency. Within our study site, each of the three wetland complexes receive tile drainage from a single agricultural field, however denitrification varies significantly between each complex. NO3-N availability limits denitrification, but limitation by PO4-P and C may further limit denitrification rates. Using a combination of laboratory and replicate treatment wetlands as an experimental system, we can test the effects of nutrient stoichiometry on denitrification potential in the laboratory and then apply the results to replicate experimental wetland systems. A preliminary study using several ratios of PO4-P in relation to NO3-N has shown the addition of P to enhance denitrification rates significantly. If PO4-P or C is found to be limiting, managing for the stoichiometric requirements of denitrifiers may ensure enhanced NO3-N removal.“