Submitted by: Thomas Butler M.S. Cornell University and Institute of Ecosystem Studies tjb2@cornell.edu
Abstract:
Reduced forms of nitrogen are readily taken up by cyanobacteria which can lead to harmful algae blooms (HABs) and increase their toxicity. These blooms have become more widespread, and have appeared in all of the NY State Finger Lakes Region in the last 10 years, including oligotrophic Skaneateles Lake. Wet and dry atmospheric nitrogen (N) inputs in the eastern USA have increasingly been dominated by reduced forms of nitrogen. Wet atmospheric deposition of NH4+ is well documented, but dry deposition of gaseous NH3 is less well characterized. To better understand the importance of landscape and direct surface NH3 deposition to Skaneateles Lake, we continuously monitored atmospheric NH3 concentrations from May 2021 to June 2022 using passive samplers with 2-week exposure times, and the protocols of the National Atmospheric Deposition Program, Ammonia Monitoring Network (NADP/AMoN). We have estimated deposition of NH3 into the terrestrial watershed using two different modeling approaches, TDep/EQUATES and STAGE, and onto the lake surface which is equal to 23% of the watershed area. We estimate that dry fluxes of NH3 represent 60% to 65% of the dry N deposition, and 20% to 30% of the total (wet + dry) N deposition. NH3 direct deposition to the lake surface accounts for an estimated 4% of the total N loading input to the lake, with an additional NH3 loading of 8% from the terrestrial watershed. If precipitation NH4+ is included, 29% of the total N load to the lake is from reduced forms of N (NH3 + NH4+). These labile N inputs may add to the formation of HABS in what is considered a very clean lake and an unfiltered drinking water source for a major metropolitan area.
Primary Session Choice: SS120 What Drives Harmful Algal Blooms in Freshwater Ecosystems and How Can We Prevent, Control, and Mitigate their Impacts?
Authors:
Thomas Butler, Cornell University and the Institute of Ecosystem Studies (tjb2@cornell.edu)
Robert Howarth, Cornell University (howarth@cornell.edu)
Dennis Swaney, CornellUniversity (dps1@cornell.edu)
Roxanne Marino, Cornell University (rmm3@cornell.edu)
Colleen Baublitz, US EPA, Office of Air Quality Planning, (Baublitz.Colleen@epa.gov)
Gregory Beachley, US EPA Clean Air Marrkets Division (Beachley.Gregory@epa.gov)