High rates of methane oxidation in an Amazon floodplain lake

• Published in: Biogeochemistry Vol. 137; no. 3; pp. 351 - 365
• Main Authors: Barbosa, Pedro M., Farjalla, Vinicius F., Melack, John M., Amaral, João Henrique F., da Silva, Jonismar S., Forsberg, Bruce R.
• Format: Journal Article
• Language: English
• Published: Cham Springer Science + Business Media 01-02-2018; Springer International Publishing; Springer Nature B.V
• Subjects: Annual variations; Biogeosciences; Earth and Environmental Science; Earth Sciences; Ecosystems; Environmental Chemistry; Floodplains; Lakes; Life Sciences; Methane; ORIGINAL PAPERS; Oxidation; River basins; Rivers; Surface water; Water levels; Methane emission; Carbon isotope fractionation; Methane oxidation; Floodplain lake; Amazon floodplain
• ISSN: 0168-2563; 1573-515X
• DOI: 10.1007/s10533-018-0425-2

Methane (CH₄) oxidation may consume large amounts of dissolved CH₄ in lakes and wetlands. Here, we estimated CH₄ oxidation rates in an Amazonian floodplain lake during periods representative of the annual variations in water level, using incubations and measurements of δ¹³C-CH₄. A large fraction of the CH₄ produced was oxidized (from 34 to ~ 100%, average = 80%), with volumetric CH₄ oxidation rates ranging from 1 to 132 mg C m⁻³ d⁻¹. Heavier values of δ¹³C-CH₄ in surface waters when compared to bottom waters and sediment bubbles corroborates the high CH₄ oxidation rates observed. The depth-integrated oxidation rates were of the same magnitude as the calculate CH₄ evasion to the atmosphere, which indicates that methane oxidation is an important sink of CH₄ and is likely to be important in the many similar lakes encountered in the Amazon River basin.