@article{fdi:010048253,
  title = {{I}nterplay between sedimentary organic matter and dissolved oxygen availability in a coastal zone of the {H}umboldt {C}urrent {S}ystem; {M}ejillones {B}ay, {N}orthern {C}hile},
  author = {{V}aldes, {J}. and {S}ifeddine, {A}bdelfettah and {O}rtlieb, {L}uc and {P}ierre, {C}.},
  editor = {},
  language = {{ENG}},
  abstract = {{G}eochemical and petrographical analyses were done in 26 surficial sediment samples from {M}ejillones {B}ay (northern {C}hile) to investigate the processes that participate in the preservation of sedimentary organic matter. {A}nnual variability of chlorophyll-a and {DIC} delta {C}-13 measured in surface waters of three different parts of {M}ejillones {B}ay did not show any significant spatial variability in biological productivity. {O}n the other hand, bottom dissolved oxygen showed strong changes associated with water depth and season. {S}urface sediment composition was statistically analyzed displaying organic facies, which are in agreement with the principal zones of bottom oxygenation (annual mean condition) identified in this bay. {I}n the oxic coastal zone (>1 ml l(-1)) the total carbon ({TC}), total nitrogen {JN}), total organic carbon ({TOC}), hydrogen index ({HI}) and oxygen index ({OI}) were 1.3%, 0.1%, 0.4%, 355.8 mg {HC}/g {TOC} and 237.6 {M}g {CO}2/g {TOC}, respectively. {T}hese results and the presence of almost exclusively dispersed amorphous organic matter suggest an environment where most metabolizable organic matter is degraded within the water-column and/or in the sediment water interface. {I}n the microxic hemipelagic zone (<0.1 ml l(-1)), located deeper than 65 m, the {TC}, {TN}, {TOC}, {HI} and {OI} were 10.5%, 1.0%, 6.6%, 529.7 mg {HC}/g {TOC} and 103.1 {M}g {CO}2/g {TOC}, respectively. {T}hese values and the presence of abundant agglomerated amorphous organic matter suggest a better preservation of metabolizable and non-metabolizable compounds. {W}e can conclude that biological productivity and dissolved oxygen exert a similar influence on the sedimentary organic matter, but the characteristics and quantity of organic material preserved in bottom sediments of this bay are controlled, principally, by the availability of dissolved oxygen at the sediment-water interface. {A}ccording to this conclusion, we suggest that the sedimentary record of {M}ejillones {B}ay must be interpreted in paleoceanographic terms primarily in relation to the temporal variability of dissolved oxygen, more than biological productivity. {T}he {OI} seems to be a good proxy of paleoxygenation in this coastal system.},
  keywords = {geochemistry ; petrography ; marine sediment ; {H}umboldt system ; {C}hile},
  booktitle = {},
  journal = {{M}arine {G}eology},
  volume = {265},
  numero = {3-4},
  pages = {157--166},
  ISSN = {0025-3227},
  year = {2009},
  DOI = {10.1016/j.margeo.2009.07.004},
  URL = {https://www.documentation.ird.fr/hor/fdi:010048253},
}