@article{fdi:010077721,
  title = {{H}ydrological control, fractionation, and fluxes of dissolved rare earth elements in the lower {O}rinoco {R}iver, {V}enezuela},
  author = {{M}ora, {A}. and {M}oreau, {C}. and {M}oquet, {J}. {S}. and {G}allay, {M}. and {M}ahlknecht, {J}. and {L}araque, {A}lain},
  editor = {},
  language = {{ENG}},
  abstract = {{T}he monthly variation of dissolved rare earth elements ({REE}s) was assessed in the lower {O}rinoco {R}iver during a two year period (2007-2008) to determine the seasonal variability of {REE} concentrations, to identify the variables that exert the main control in their concentrations and fractionation, and to quantify the annual fluxes of dissolved {REE}s to the {O}rinoco estuary. {O}verall, the abundance of dissolved {REE}s is dominated by hydrological variations in the water discharge, wherein the lowest concentrations and greater fractionation occur during low water-discharge periods. {T}he p{H} and {A}l- and {F}e-mineral colloids are identified as the main variables that control both the abundance and fractionation of dissolved {REE}s. {A}n enrichment of heavy {REE}s ({HREE}s) relative to light {REE}s ({LREE}s) occurs at circumneutral and alkaline p{H} values. {H}owever, the logarithmic relationships between the {Y}bucc/{N}ducc ratios and {A}l and {F}e concentrations indicate that {A}l- and {F}e-mineral colloids are responsible for the progressive enrichment of {LREE}s relative to {HREE}s under acidic conditions. {T}he {C}e and {E}u anomalies are also dominated by variations in the water discharge. {N}egative {C}e-anomalies are observed during low flow periods. {T}his is probably due to the signature of the {A}ndean host rocks and/or the oxidation and co-precipitation of {C}e ({III}) to {C}e{O}2 at alkaline p{H}. {H}owever, the lesser {C}e fractionated values during flood/high-water periods may indicate less oxidized/more reduced source conditions during these periods. {C}onversely, positive {E}u anomalies are observed during low-water periods because of the preferential weathering of plagioclase in shield terranes and {E}u-bearing minerals in the {A}ndes. {T}he fluxes of dissolved {REE}s from the lower {O}rinoco {R}iver to the {O}rinoco estuary display strong inter-annual variations, which range from 45.6% for {L}u to 56.5% for {G}d. {T}hese results highlight the importance of performing monthly and inter-annual {REE} time series in order to develop a more precise quantification of the annual {REE} fluxes from large rivers to the oceans.},
  keywords = {{R}are earth elements ; {O}rinoco {R}iver ; {H}ydrological variation ; {A}tlantic ocean ; {N}d fluxes ; {VENEZUELA} ; {ORENOQUE} {COURS} {D}'{EAU} ; {ATLANTIQUE}},
  booktitle = {},
  journal = {{A}pplied {G}eochemistry},
  volume = {112},
  numero = {},
  pages = {art. 104462 [11p.]},
  ISSN = {0883-2927},
  year = {2020},
  DOI = {10.1016/j.apgeochem.2019.104462},
  URL = {https://www.documentation.ird.fr/hor/fdi:010077721},
}