@article{8fa4a710fe624b6682c87d04ff1757bb,
title = "Erosion of organic carbon from the Andes and its effects on ecosystem carbon dioxide balance",
abstract = "Productive forests of the Andes are subject to high erosion rates that supply to the Amazon River sediment and carbon from both recently photosynthesized biomass and geological sources. Despite this recognition, the source and discharge of particulate organic carbon (POC) in Andean Rivers remain poorly constrained. We collected suspended sediments from the Kos{\~n}ipata River, Peru, over 1 year at two river gauging stations. Carbon isotopes (14C, 13C, and 12C) and nitrogen to organic carbon ratios of the suspended sediments suggest a mixture of POC from sedimentary rocks (POCpetro) and from the terrestrial biosphere (POCbiosphere). The majority of the POCbiosphere has a composition similar to surface soil horizons, and we estimate that it is mostly younger than 850 14C years. The suspended sediment yield in 2010 was 3500 ± 210 t km−2 yr−1, >10 times the yield from the Amazon Basin. The POCbiosphere yield was 12.6 ± 0.4 t C km−2 yr−1 and the POCpetro yield was 16.1 ± 1.4 t C km−2 yr−1, mostly discharged in the wet season (December to March) during flood events. The river POCbiosphere discharge is large enough to play a role in determining whether Andean forests are a source or sink of carbon dioxide. The estimated erosional discharge of POCpetro from the Andes is much larger (~1 Mt C yr−1) than the POCpetro discharge by the Madeira River downstream in the Amazon Basin, suggesting that oxidation of POCpetro counters CO2 drawdown by silicate weathering. The flux and fate of Andean POCbiosphere and POCpetro need to be better constrained to fully understand the carbon budget of the Amazon River basin.",
keywords = "Andes, biogeochemistry, carbon cycle, organic carbon, rivers, suspended sediment",
author = "Clark, {K. E.} and Hilton, {R. G.} and West, {A. J.} and {Robles Caceres}, A. and Gr{\"o}cke, {D. R.} and Marthews, {T. R.} and Ferguson, {R. I.} and Asner, {G. P.} and M. New and Y. Malhi",
note = "Funding Information: This paper is a product of the Andes Biodiversity and Ecosystems Research Group (ABERG). K.E.C. was funded by the Natural Sciences and Engineering Research Council of Canada (362718-2008 PGS-D3) and Clarendon Fund PhD scholarships. R.G.H. was supported by a NERC New Investigator Grant (NE/I001719/1) and a European Research Council Starting Grant ROC-CO2 (678779). A.J.W. was supported to work in the Kos{\~n}ipata catchment by NSF-EAR 1227192 and 1455352. Y.M. is supported by the Jackson Foundation and a European Research Council advanced investigator grant GEM-TRAITS (321131) under the European Union's Seventh Framework Programme (FP7/2007–2013). We thank ACCA Peru (Wayqecha) and Inkaterra (San Pedro) for the field support and L.V. Morales, R.J. Abarca Mart{\'i}nez, M.H. Yucra Hurtado, R. Paja Yurca, J.A. Gibaja Lopez, I. Cuba Torres, J. Huam{\'a}n Ovalle, A. Alfaro-Tapia, R. Butr{\'o}n Loayza, J. Farfan Flores, D. Oviedo Licona, and D. Ocampo for the field assistance. The Carnegie Airborne Observatory is made possible by the Avatar Alliance Foundation, Grantham Foundation for the Protection of the Environment, John D. and Catherine T. MacArthur Foundation, Gordon and Betty Moore Foundation, W.M. Keck Foundation, Margaret A. Cargill Foundation, Mary Anne Nyburg Baker and G. Leonard Baker Jr., and William R. Hearst III. We thank D. Knapp, T. Kennedy-Bowdoin, C. Anderson, and R. Tupayachi for the CAO data collection and analysis. We thank S. Waldron, S. Dadson, S. Lane, S. Feakins, and C. Ponton for their helpful discussions and comments prior to submission and V. Galy for suggesting the radiocarbon analysis of the poststorm samples. We thank Editor M. Goni and two anonymous reviewers for their comments on the paper which helped improve the manuscript. Data not included in the tables in this paper or its supporting information are available in association with cited publications, including discharge and stage height records [Clark et al., http://dx.doi.org/10.4211/hs.5f432a520370472683b543d493f136d1] and the Kos{\~n}ipata valley landslide inventory [Clark et al., http://dx.doi.org/10.4211/hs.90487bcf16e44c62a677ae33ef95e968]. Publisher Copyright: {\textcopyright}2017. American Geophysical Union. All Rights Reserved.",
year = "2017",
month = mar,
day = "1",
doi = "10.1002/2016JG003615",
language = "English (US)",
volume = "122",
pages = "449--469",
journal = "Journal of Geophysical Research: Biogeosciences",
issn = "2169-8953",
number = "3",
}