Fluvial carbon export from a lowland Amazonian rainforest in relation to atmospheric fluxes

Vihermaa, L. E., Waldron, S. , Domingues, T., Grace, J., Cosio, E. G., Limonchi, F., Hopkinson, C., Ribeiro da Rocha, H. and Gloor, E. (2016) Fluvial carbon export from a lowland Amazonian rainforest in relation to atmospheric fluxes. Journal of Geophysical Research: Biogeosciences, 121(12), pp. 3001-3018. (doi:10.1002/2016JG003464)

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Abstract

We constructed a whole carbon budget for a catchment in the Western Amazon Basin, combining drainage water analyses with eddy covariance measured terrestrial CO2 fluxes. As fluvial C export can represent permanent C export it must be included in assessments of whole site C balance, but is rarely done. The footprint area of the flux tower is drained by two small streams (~5-7 km2) from which we measured the dissolved inorganic carbon (DIC), dissolved organic carbon (DOC), particulate organic carbon (POC) export and CO2 efflux. The EC measurements showed the site C balance to be +0.7 ± 9.7 Mg C ha-1 yr-1 (a source to the atmosphere) and fluvial export was 0.3 ± 0.04 Mg C ha-1 yr-1. Of the total fluvial loss 34% was DIC, 37% DOC and 29% POC. The wet season was most important for fluvial C export. There was a large uncertainty associated with the EC results and with previous biomass plot studies (-0.5 ± 4.1 Mg C ha-1 yr-1), hence it cannot be concluded with certainty whether the site is C sink or source. The fluvial export corresponds to only 3-7 % of the uncertainty related to the site C balance, thus other factors need to be considered to reduce the uncertainty and refine the estimated C balance. However, stream C export is significant, especially for almost neutral sites where fluvial loss may determine the direction of the site C balance. The fate of C downstream then dictates the overall climate impact of fluvial export.

Item Type:Articles
Additional Information:This work relates to the NERC funded Amazonica project (NE/F005040/1) - held by University of Edinburgh, ended 30 June 2014.
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Waldron, Professor Susan and Vihermaa, Dr Leena
Authors: Vihermaa, L. E., Waldron, S., Domingues, T., Grace, J., Cosio, E. G., Limonchi, F., Hopkinson, C., Ribeiro da Rocha, H., and Gloor, E.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Journal of Geophysical Research: Biogeosciences
Publisher:American Geophysical Union
ISSN:2169-8953
ISSN (Online):2169-8961
Published Online:27 October 2016
Copyright Holders:Copyright © 2016 American Geophysical Union
First Published:First published in Journal of Geophysical Research: Biogeosciences 121(12):3001-3018
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
467662Amazon Integrated Carbon Analysis (AMAZONICA)Susan WaldronNatural Environment Research Council (NERC)NE/F005482/1SCHOOL OF GEOGRAPHICAL & EARTH SCIENCES