High contribution of methane in greenhouse gas emissions from a eutrophic lake: a mass balance synthesis

Arianto B. Santoso, David P. Hamilton, Louis A. Schipper, Ilia S. Ostrovsky, Chris H. Hendy

Research output: Contribution to journalArticlepeer-review


Lakes are ‘hotspots’ for greenhouse gas (GHG) emissions, primarily carbon dioxide (CO2) and methane (CH4). Understanding the processes regulating GHG emissions from lakes, and their temporal variability, is essential for more accurately quantifying the role of lakes in global GHG cycles. In this study, we identified the processes that affect CO2 and CH4 concentrations in a small (0.3 km2) eutrophic monomictic lake (Okaro, New Zealand). A mass balance model was used to calculate changes in CO2 and CH4 storage in the lake as a result of internal cycling and atmospheric fluxes. To support model computations, CO2 and CH4 concentrations profiles were measured monthly over a one-year period, in addition to temperature, dissolved oxygen and chlorophyll a. Annually, Lake Okaro acted as a sink of CO2 from the atmosphere (425.4 mmol CO2 m−2 y−1) and a source of CH4 (553.4 mmol CH4 m−2 y−1) equating to a net GHG emission (diffusive fluxes of CO2 and CH4 combined) of 0.22 kg CO2-eq m−2 y−1. Although it may be viewed as conservative and applies only to diffusive fluxes, our study indicates that eutrophic lakes with high rates of primary production may act as a net source of GHGs.

Original languageEnglish
Pages (from-to)411-430
Number of pages20
JournalNew Zealand Journal of Marine and Freshwater Research
Issue number3
StatePublished - 2021
Externally publishedYes

Bibliographical note

Publisher Copyright:
© 2020 The Royal Society of New Zealand.


  • CH
  • CO
  • Lake
  • eutrophic
  • greenhouse gas
  • thermal stratification

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Aquatic Science
  • Ecology
  • Water Science and Technology


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