Nitrogen-fixation and Denitrification Rates in the Water Column and Sediments of Minnesota Lakes: Challenging assumptions on where these processes are important and how they contribute to the nitrogen budget of lakes

nitrogen fixation
Friday, Dec. 10th, 3pm

375 Borlaug Hall

Brianna Loeks-Johnson
WRS Doctoral Candidate

Abstract

 Understanding nitrogen cycling and budgets in lakes is important for management strategies around eutrophication. When studying these budgets, many scientists assume that the microbial mediated processes of denitrification (which removes nitrogen) occurs in the sediments and nitrogen fixation (which brings nitrogen in) occurs in the surface waters. We have set out to challenge these assumptions and quantify how important these processes are throughout the water column and sediments in lakes across Minnesota and Western Wisconsin. We have found that these assumptions are not always accurate and could result in detrimental miscalculations in lake nitrogen budgets, and a more thorough analysis of nitrogen inputs and outputs are required for accurate management.