Concentrations of beta-carotene, astaxanthin, canthaxanthin, and diatoxanthine of ODP Leg 112 samples (Table 2)

The quantitative distribution of carotenoids in sediments of Pleistocene to Miocene age from the Peru upwelling area is reported. Major pigments include beta-carotene, diatoxanthin, caroteno-3,3'-diols from phytoplankton, astaxanthin and canthaxanthin from crustaceans, and spheroidenone from bacteria. beta-carotene epoxides are major consituents, representing transformation products in the degradation of beta-carotene to low molecular weight compounds. The absolute abundance of carotenoids reflects bottom-water oxicity at the time of deposition; highest concentrations of carotenoids were observed in laminated muds deposited within the oxygen-minimum zone, with reduced or negligible concentrations of pigments observed in bioturbated sequences deposited during periods of well-oxygenated bottom water. beta-carotene, the most abundant pigment in recently deposited sediments, slowly degrades through a sequence of transformation reactions initiated by epoxidation. The 4,4' dioxo-carotenoids, which are unable to form 5,6-epoxides, have been preferentially preserved in these sediments.