Structural comparison of algal microfossils with extant algaenans using ruthenium tetroxide degradation

Abstract

Algaenans are non-hydrolysable biopolymers present in the cell walls of specific freshwater and marine microalgae. As a consequence of their high resistance algaenans are selectively preserved upon sedimentation and burial in the sediments. Upon chemical analysis of algaenan isolated from some green microalgae it was shown that most algaenans share the same chemical features i. e. highly aliphatic and probably cross-linked by ether linkages. Analysis of the Ru04 product mixtures derived from the sediments and comparison with the Ru0₄ degradation products from algaenans isolated from cultured algae showed that the algaenans present in these sediments are virtually identical to those from cultured algae and did not undergo severe alterations upon sedimentation and subsequent burial in the sediments. The differences between the sedimentary material and algaenans are probably mainly caused by the presence of other micrafossils and because manomers that are only ester-linked to the polymer matrix in the case of T. minimum and P. botyanum algaenan are removed from the algaenan during diagenesis. These findings clearly illustrate that selective preservation of resistant algaenans can be an important process in the preservation of sedimentary organic matter in lacustrine sediments.