Open AccessInput of particulate organic and dissolved inorganic carbon from the Amazon to the Atlantic Ocean
Author(s) -
Druffel E. R. M.,
Bauer J. E.,
Griffin S.
Publication year - 2005
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1029/2004gc000842
Subject(s) - amazon rainforest , dissolved organic carbon , river mouth , remineralisation , plume , oceanography , total organic carbon , geology , particulates , organic matter , salinity , isotopes of carbon , carbon fibers , total inorganic carbon , environmental science , radiocarbon dating , hydrology (agriculture) , environmental chemistry , carbon dioxide , geomorphology , sediment , chemistry , paleontology , geography , materials science , fluoride , ecology , composite number , composite material , biology , geotechnical engineering , organic chemistry , meteorology , inorganic chemistry
We report concentrations and isotope measurements (radiocarbon and stable carbon) of dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POC) in waters collected from the mouth of the Amazon River and the North Brazil Current. Samples were collected in November 1991, when the Amazon hydrograph was at its annual minimum and the North Brazil Current had retroflected into the equatorial North Atlantic. The DIC Δ 14 C results revealed postbomb carbon in river and ocean waters, with slightly higher values at the river mouth. The low DIC δ 13 C signature of the river end‐member (−11‰) demonstrates that about half of the DIC originated from the remineralization of terrestrially derived organic matter. A linear relationship between DIC and salinity indicates that DIC was mixed nearly conservatively in the transition zone from the river mouth to the open ocean, though there was a small amount (≤10%) of organic matter remineralization in the mesohaline region. The POC Δ 14 C values in the river mouth were markedly lower than those values from the western Amazon region (Hedges et al., 1986). We conclude that the dominant source of POC near the river mouth and in the inner Amazon plume during November 1991 was aged, resuspended material of significant terrestrial character derived from shelf sediments, while the outer plume contained mainly marine‐derived POC.