Large increases in emissions of methane and nitrous oxide from eutrophication in Lake Erie [article]

Julianne M. Fernandez, Amy Townsend-Small, Arthur Zastepa, Susan B. Watson, Jay A. Brandes
2019 bioRxiv   pre-print
Eutrophication is linked to greenhouse gas emissions from inland waters. Phytoplankton blooms in Lake Erie, one of Earth's largest lakes, have increased with nutrient runoff linked to climate warming, although greenhouse gas emissions from this or other large eutrophic lakes are not well characterized. We measured greenhouse gases around Lake Erie in all four seasons and found that CH4 and N2O emissions have increased 10 times or more with re-eutrophication, especially during and after
more » ... and after phytoplankton blooms. Lake Erie is a positive source of CH4 throughout the entire year and around the entire lake, with the highest emissions in spring and summer near the mouth of the Maumee River. While Lake Erie is an overall N2O source, it is an N2O sink in winter throughout the lake and in some locations during large phytoplankton blooms. We estimate that Lake Erie emits ~6300 metric tons of CH4-C yr-1 (± 19%) and ~600 metric tons N2O-N yr-1 (± 37%): almost 500,000 metric tons CO2-eq yr-1 total. These results highlight the gravity of eutrophication-related increases in large lake GHG emissions: an overlooked, but potentially major feedback to global climate change.
doi:10.1101/648154 fatcat:4um5xbpe6jeepebuv6ytfenecy