POLLEN MINERALIZATION RATES: IS POLLEN A SUBSTANTIAL SOURCE OF CARBON AND NUTRIENTS INTO THE LAURENTIAN GREAT LAKES?

Pollen is a ubiquitous particulate regarded as recalcitrant organic matter (OM) in aquatic environments, seasonally introducing undetermined quantities of terrigenous OM to inland lakes, a fraction of which survives water column settling and sediment burial. Carbon (C) and nutrients have been shown to rapidly leach from pollen after aquatic deposition, ranging from a few days to weeks, with upwards of 50% carbon by weight leached into surrounding waters. The role of pollen as a carbon and nutrient delivery mechanism for Laurentian Great Lake (LGL) Superior has not been explored. Our recent study, as a part of the Great Lakes Sediment Surveillance Project, suggests that conifer pollen accounts for delivery of up to 0.19 Tg C to LGL Superior sediments annually. In this study, we examined the effects of pollen mineralization on organic C and nutrient availability in waters of LGL Superior to evaluate its potential as an unquantified perennial source of C, nitrogen (N), and phosphorus (P). Pollen standards were added to water collected from LGL Superior, incubated for up to 30 days, and measured for dissolved and particulate fractions of C, N, and P. Preliminary results show a 33% increase in dissolved organic carbon concentration within the first week of incubation, with subsequent nine-fold and two-fold increases in ammonium and phosphate concentrations, respectively. These results suggest pollen contains a labile fraction of OM that is a substantial source of C, N, and P that must be integrated into nutrient budgets of LGL Superior and, more broadly, low nutrient lakes.

Presentation Preference: Oral

Primary Presenter: Jake Zunker, University of Minnesota Duluth (zunke018@d.umn.edu)

Authors:

Jake Zunker, University of Minnesota Duluth  (zunke018@d.umn.edu)

Millenia Calvin, LeMoyne-Owen College  (mcalvin568@loc.edu)

Kathryn Schreiner, University of Minnesota Duluth  (kschrein@d.umn.edu)

Christopher Filstrup, University of Minnesota Duluth  (filstrup@d.umn.edu)

Chan Lan Chun, University of Minnesota Duluth  (chun0157@d.umn.edu)