A carbon mass balance for Lake Erie: sources and composition

Session: 62. - Distilling a Career: A Tribute to Doug Haffner?s Contributions to Environmental Research on Large Lakes

Christina Fasching, Trent University, christinafasching@trentu.ca
Stephen Oni, Trent University, soni@trentu.ca
Erin Hillis, University of Windsor- GLIER, hillise@uwindsor.ca
Paul Frost, Trent University, paulfrost@trentu.ca
G. Doug Haffner, Great Lakes Institute, Univ. of Windsor, haffner@uwindsor.ca
Todd Howell, Ontario Ministry of the Environment, Env. Monitoring & Reporting Br, todd.howell@ontario.ca
Marten Koops, Fisheries & Oceans Canada, marten.koops@dfo-mpo.gc.ca
Chris Marvin, Environment and Climate Change Canada, chris.marvin@canada.ca
Richard Vogt, Trent University, richvogt@gmail.com
Susan Watson, University of Waterloo, jkswatson@shaw.ca
Arthur Zastepa, Environment and Climate Change Canada, arthur.zastepa@canada.ca
Marguerite Xenopoulos, Trent University, mxenopoulos@trentu.ca

Abstract

Inland lakes are hotspots of carbon (C) storage and transformation, and play a disproportionately large role in the global carbon cycle considering their relative size. Knowledge and processes established for small to medium size lakes, may not extrapolate to large lake ecosystems due to their vast spatial scales, which may decouple landscape influences on carbon cycles. Here we present a first approximation for the Lake Erie carbon mass balance, considering C sources and composition. DOC and DIC at the lake’s outlet increased by 10% and 4% relative to the riverine inputs, respectively. Although lake inflow was characterized by humic and aromatic DOM, the lake exported 30% more protein-like fluorescence than riverine inputs, suggesting transformation by in-lake processes. In fact, carbon fixed from primary production was the biggest pool of C in Lake Erie at 9.12TgCyr^-1. In contrast, deeper lake water exhibited a humic-like DOM signature with high aromaticity, indicating a storage of terrestrial DOM derived from tributaries. Overall, DIC increased with aromaticity, suggesting the majority of CO₂ produced originated from imported terrestrial sources. Our findings highlight how in-stream processes contribute to DOM transformation processes and further constrains current estimates of lake contributions to the global C budget.

1. Keyword
biogeochemistry

2. Keyword
Lake Erie

3. Keyword
carbon cycle

4. Additional Keyword
Dissolved organic matter