Carbone organique dissous dans des lagons d'atoll, par combustion catalytique à haute température et par spectrophotométrie

Abstract : Two surveys were carried out on ten atolls in the Tuamotu archipelago (French Polynesia, Pacific Ocean). In vitro UV (250–400 nm) spectra of water samples gave absorption at 254 nm, A254, and spectrum slope, S⋆ (computed from In Aλ versus λ).These two descriptors are negatively correlated, and data points are arrayed along a hyperbola spanned between an oceanic pole (high S⋆, low A254) and a confined pole (low 5⋆, high A254). Dissolved organic carbon (DOC) concentrations, [C], as assessed by HTCO, exhibit a narrow range (0.7–1.0 mg C.L−1 for most lagoons) contrasting with the wide diversity of optical characteristics. [C] and A254 are positively correlated, with a significant intercept (0.5 mg C.L−1) representing non-chromophoric DOC. Carbon-specific absorption, ε254 increases (from 0.4 to 1.3 m2.g−1) with increasing [C], mainly according to the literature) owing to increased average molecular weight (MW) of the chromophoric DOC fraction, which also lowers S⋆. Our optical data thus illustrate a gradient of confinement (or residence time) that corresponds to a continuum in DOC nature, especially in MW and hence in bioavailability. Optical methods are confirmed as quick and effective means of assessing DOM distribution.
Document type :
Journal articles
Complete list of metadatas

https://hal-amu.archives-ouvertes.fr/hal-02062734
Contributor : Richard Sempere <>
Submitted on : Saturday, March 9, 2019 - 6:57:27 PM
Last modification on : Tuesday, March 26, 2019 - 11:29:18 AM
Long-term archiving on : Monday, June 10, 2019 - 4:55:56 PM

Licence


Distributed under a Creative Commons Attribution 4.0 International License

Identifiers

Citation

Jean Pagès, Jean-Pascal Torreton, Richard Sempere. Carbone organique dissous dans des lagons d'atoll, par combustion catalytique à haute température et par spectrophotométrie. Comptes Rendus Géoscience, Elsevier Masson, 1997, 324 (11), pp.915-922. ⟨10.1016/S1251-8050(97)82505-0⟩. ⟨hal-02062734⟩

Share

Metrics

Record views

74

Files downloads

51