@article{fdi:010061964,
  title = {{S}ource, transport and fluxes of {A}mazon {R}iver particulate organic carbon : insights from river sediment depth-profiles},
  author = {{B}ouchez, {J}. and {G}aly, {V}. and {H}ilton, {R}. {G}. and {G}aillardet, {J}. and {M}oreira {T}urcq, {P}atricia and {P}erez, {M}. {A}. and {F}rance-{L}anord, {C}. and {M}aurice, {L}aurence},
  editor = {},
  language = {{ENG}},
  abstract = {{I}n order to reveal particulate organic carbon ({POC}) source and mode of transport in the largest river basin on {E}arth, we sampled the main sediment-laden tributaries of the {A}mazon system ({S}olimoes, {M}adeira and {A}mazon) during two sampling campaigns, following vertical depth-profiles. {T}his sampling technique takes advantage of hydrodynamic sorting to access the full range of solid erosion products transported by the river. {U}sing the {A}l/{S}i ratio of the river sediments as a proxy for grain size, we find a general increase in {POC} content with {A}l/{S}i, as sediments become finer. {H}owever, the sample set shows marked variability in the {POC} content for a given {A}l/{S}i ratio, with the {M}adeira {R}iver having lower {POC} content across the measured range in {A}l/{S}i. {T}he {POC} content is not strongly related to the specific surface area ({SSA}) of the suspended load, and bed sediments have a much lower {POC}/{SSA} ratio. {T}hese data suggest that {SSA} exerts a significant, yet partial, control on {POC} transport in {A}mazon {R}iver suspended sediment. {W}e suggest that the role of clay mineralogy, discrete {POC} particles and rock-derived {POC} warrant further attention in order to fully understand {POC} transport in large rivers. {T}o examine the source of {POC} in the {A}mazon {B}asin in more detail, we use radiocarbon ({C}-14) content and the stable isotope composition (delta {C}-13) of {POC}. {C}-14 activity demonstrates that rock-derived {POC} is a significant component of river bed sediments and contributes to {POC} across the river depth-profiles of suspended sediments. {W}e estimate that the flux of rock-derived {POC} may reach similar to 10% of the total {POC} export by the {A}mazon {R}iver. {A}fter correcting for rock-derived {POC} input, we find that {POC} from the terrestrial biosphere (biospheric {POC}) is mostly sourced from {C}3-plants. {H}igher biospheric {POC} delta {C}-13 values in the {M}adeira {R}iver (by similar to 0.5-1 parts per thousand) are best explained by a small (<5%) contribution of {C}4-grasses from {B}olivian savannas. {F}inally, we use {C}-14 to estimate the mean age of biospheric {POC} exported from the {A}mazon {B}asin. {T}he data show that biospheric {POC} is younger in the {S}olimoes {R}iver (1120 years) than in the {M}adeira {R}iver (2850 years). {T}hese ages are much younger than the corresponding estimates of sediment residence time in the basin, suggesting that lowland areas and/or young {POC} from above-ground biomass may contribute disproportionately to the biomarker signals in terrigenous sediments of the {A}mazon delta.},
  keywords = {{AMAZONE} {BASSIN}},
  booktitle = {},
  journal = {{G}eochimica et {C}osmochimica {A}cta},
  volume = {133},
  numero = {},
  pages = {280--298},
  ISSN = {0016-7037},
  year = {2014},
  DOI = {10.1016/j.gca.2014.02.032},
  URL = {https://www.documentation.ird.fr/hor/fdi:010061964},
}