Oxidative mitigation of aquatic methane emissions in large Amazonian rivers

Author(s)

Sawakuchi, Henrique O. ^[1] ; Bastviken, David ^[2] ; Sawakuchi, Andre O. ^[3] ; Ward, Nicholas D. ^[4] ; Borges, Clovis D. ^[1] ; Tsai, Siu M. ^[1] ; Richey, Jeffrey E. ^[5] ; Ballester, Maria Victoria R. ^[1] ; Krusche, Alex V. ^[1]

Affiliation

^[1] Univ Sao Paulo, Ctr Nucl Energy Agr, Ave Centenario 303, BR-13400970 Piracicaba, SP - Brazil

^[2] Linkoping Univ, Dept Themat Studies Environm Change, SE-58183 Linkoping - Sweden

^[3] Univ Sao Paulo, Inst Geosci, Dept Sedimentary & Environm Geol, Rua Lago 562, BR-05508080 Sao Paulo, SP - Brazil

^[4] Univ Florida, Dept Geol Sci, Box 112120, Gainesville, FL 32611 - USA

^[5] Univ Washington, Sch Oceanog, Seattle, WA 98195 - USA

• Document type: Journal article
• Source: GLOBAL CHANGE BIOLOGY; v. 22, n. 3, p. 1075-1085, MAR 2016.
• Web of Science Citations: 18

Abstract

The flux of methane (CH4) from inland waters to the atmosphere has a profound impact on global atmospheric greenhouse gas (GHG) levels, and yet, strikingly little is known about the dynamics controlling sources and sinks of CH4 in the aquatic setting. Here, we examine the cycling and flux of CH4 in six large rivers in the Amazon basin, including the Amazon River. Based on stable isotopic mass balances of CH4, inputs and outputs to the water column were estimated. We determined that ecosystem methane oxidation (MOX) reduced the diffusive flux of CH4 by approximately 28-96% and varied depending on hydrologic regime and general geochemical characteristics of tributaries of the Amazon River. For example, the relative amount of MOX was maximal during high water in black and white water rivers and minimal in clear water rivers during low water. The abundance of genetic markers for methane-oxidizing bacteria (pmoA) was positively correlated with enhanced signals of oxidation, providing independent support for the detected MOX patterns. The results indicate that MOX in large Amazonian rivers can consume from 0.45 to 2.07 Tg CH4 yr(-1), representing up to 7% of the estimated global soil sink. Nevertheless, climate change and changes in hydrology, for example, due to construction of dams, can alter this balance, influencing CH4 emissions to atmosphere. (AU)

• FAPESP's process: 08/58089-9 - The role of rivers on the regional carbon cycle
• Grantee: Maria Victoria Ramos Ballester
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 11/14502-2 - Regulating factors of methane (CH4) emission in depositional environments of the Rivers Negro, Tapajos, Xingu and Amazonas
• Grantee: Henrique Oliveira Sawakuchi
• Support Opportunities: Scholarships in Brazil - Doctorate
• FAPESP's process: 12/17359-9 - Methane flux from rivers and different approaches for estimate methane production and oxidation from inland water systems
• Grantee: Henrique Oliveira Sawakuchi
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• FAPESP's process: 11/06609-1 - Provenance, transport and storage of sediments in Amazon rivers
• Grantee: André Oliveira Sawakuchi
• Support Opportunities: Regular Research Grants
• FAPESP's process: 08/58114-3 - Monitoring the microbial diversity and functional activities in response to land-use changes and deforestation under soybean and sugarcane cultivations
• Grantee: Tsai Siu Mui
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants