@article{PAR00002988,
  title = {{C}ontrasted distributions of triterpene derivatives in the sediments of {L}ake {C}a{\c{c}}ó reflect paleoenvironmental changes during the last 20,000 yrs in {NE} {B}razil},
  author = {{J}acob, {J}. and {D}isnar, {J}.{R}. and {B}oussafir, {M}. and {S}padano {A}lbuquerque, {A}.{L}. and {S}ifeddine, {A}bdelfettah and {T}urcq, {B}runo},
  editor = {},
  language = {{ENG}},
  abstract = {{L}ipid fractions extracted from sediment layers deposited in a small {B}razilian lake during the last 20,000 yrs were investigated by gas chromatography-mass pectrometry. {C}onsiderable differences in the distribution and the amount of triterpene derivatives in the aliphatic as well as in the aromatic fractions were observed all along the series. {A}lthough no precise identification of these compounds was undertaken, our interpretation of mass spectral data allowed us discriminating between des-{A}-triterpenes, mono- and triaromatic derivatives of pentacyclic triterpenes and a series of compounds tentatively identified as diaromatic derivatives of tetracyclic triterpenes. {T}he largest compound diversity was found in the lowest levels of the series dated back to the end of the {L}ast {G}lacial {M}aximum when good preservation of terrestrial plant debris was ensured by rapid burial in a semi-arid climate. {T}hen, except for a period corresponding to the {Y}ounger {D}ryas, only des-{A}-lupane was detected in significant amounts. {T}he high predominance of des-{A}-lupane is interpreted as resulting from the development of a belt of {E}leocharis sp. (spike-rush) that filtered most of organic inputs from the catchment and was the site of des-{A}-lupane production and exportation towards the lake centre. {D}uring the {Y}ounger {D}ryas, a strong influx of des-{A}lupane is attributed to the destruction of the spike-rush belt consecutive to the lowering of the lake level under drier conditions. {T}he temporary destruction of this barrier allowed other triterpene derivatives to reach the lake. {T}he distinct dynamics of des-{A} and aromatic triterpenes derivatives under variable medium conditions led us to hypothesise that these two families of compounds derive from distinct pools that contributed differently to the sediment depending on environmental and climatic conditions. {D}es-{A}-lupane was most probably produced in sub-aquatic conditions within the belt of spike-rush. {R}eversely, aromatic derivatives of triterpenes could have resulted from the degradation of their biological precursors within reducing micro-environments in the catchment.},
  keywords = {{BRESIL}},
  booktitle = {},
  journal = {{O}rganic {G}eochemistry},
  volume = {38},
  numero = {},
  pages = {180--197},
  year = {2007},
  DOI = {10.1016/j.orggeochem.2006.10.007},
  URL = {https://www.documentation.ird.fr/hor/{PAR}00002988},
}