Velocity-amplified microbial respiration rates in the lower Amazon River

Author(s):Show less -

Ward, Nicholas D. ; Sawakuchi, Henrique O. ; Neu, Vania ; Less, Diani F. S. ; Valerio, Aline M. ; Cunha, Alan C. ; Kampel, Milton ; Bianchi, Thomas S. ; Krusche, Alex V. ; Richey, Jeffrey E. ; Keil, Richard G.

• Document type: Journal article
• Source: LIMNOLOGY AND OCEANOGRAPHY LETTERS; v. 3, n. 3, p. 10-pg., 2018-06-01.

Abstract

Most measurements of respiration rates in large tropical rivers do not account for the influence of river flow conditions on microbial activity. We developed a ship-board spinning incubation system for measuring O-2 drawdown under different rotation velocities and deployed the system along the lower Amazon River during four hydrologic periods. Average respiration rates in incubation chambers rotated at 0.22 m s(-1) and 0.66 m s(-1) were 1.4 and 2.4 times higher than stationary chambers, respectively. On average, depth-integrated respiration rates in chambers spun at 0.22 m s(-1) and 0.66 m s(-1) accounted for 64%+/- 622% and 104%+/- 636% of CO2 outgassing rates, respectively, in mainstem sites. Continuous measurements of in situ pCO(2) were also made along with cross-channel profiles of river velocity. A positive correlation between river velocity and pCO(2) was observed along the lower river (r(2)=0.67-0.96) and throughout a tidal cycle. (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