Please use this identifier to cite or link to this item:
Title: Factors controlling water-column respiration in rivers of the central and southwestern Amazon Basin
Authors: Ellis, Erin E.
Richey, Jeffrey E.
Aufdenkampe, Anthony K.
Krusche, Alex Vladimir
Quay, Paul D.
Salimon, Cleber Ibraim
Cunhae, Hilandia Brandão da
Keywords: Carbon Cycle
Concentration (composition)
Dissolved Oxygen
Organic Carbon
Oxygen Isotope
Particulate Organic Matter
Primary Production
Regression Analysis
Water Column
Amazon Basin
Issue Date: 2012
metadata.dc.publisher.journal: Limnology and Oceanography
metadata.dc.relation.ispartof: Volume 57, Número 2, Pags. 527-540
Abstract: We examined the factors controlling the variability in water-column respiration rates in Amazonian rivers. Our objectives were to determine the relationship between respiration rates and the in situ concentrations of the size classes of organic carbon (OC), and the biological source (C 3 and C 4 plants and phytoplankton) of organic matter (OM) supporting respiration. Respiration was measured along with OC size fractions and dissolved oxygen isotopes (δ 18O-O 2) in rivers of the central and southwestern Amazon Basin. Rates ranged from 0.034 μmol O 2 L -1 h -1 to 1.78 μmol O 2 L -1 h -1, and were four-fold higher in rivers with evidence of photosynthetic production (demonstrated by δ 18O-O 2,<24.2%) as compared to rivers lacking such evidence (δ 18O-O 2.24.2%; 1.35±0.22 vs. 0.30±0.29 μmol L -1 h -1). Rates were likely elevated in the former rivers, which were all sampled during low water, due to the stimulation of heterotrophic respiration via the supply of a labile, algal-derived substrate and/or the occurrence of autotrophic respiration. The organic composition of fine particulate OM (FPOM) of these rivers is consistent with a phytoplankton origin. Multiple linear regression analysis indicates that [FPOC], C:N FPOC ratios, and [O 2] account for a high amount of the variability in respiration rates (r 2=0.80). Accordingly, FPOC derived from algal sources is associated with elevated respiration rates. The δ 13C of respiration-derived CO 2 indicates that the role of phytoplankton, C 3 plants, and C 4 grasses in supporting respiration is temporally and spatially variable. Future scaling work is needed to evaluate the significance of phytoplankton production to basin-wide carbon cycling. © 2012, by the Association for the Sciences of Limnology and Oceanography, Inc.
metadata.dc.identifier.doi: 10.4319/lo.2012.57.2.0527
Appears in Collections:Artigos

Files in This Item:
There are no files associated with this item.

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.