J. Villanueva et Dw. Hastings, A century-scale record of the preservation of chlorophyll and its transformation products in anoxic sediments, GEOCH COS A, 64(13), 2000, pp. 2281-2294
We have determined the chlorophyll pigment composition by liquid chromatogr
aphy (LC) and LC/MS/MS in a 1.45-m long freeze core, representing 157 years
of annually varved sedimentation, from Saanich Inlet, B.C, Canada. We inve
stigated the very early diagenetic processes of chlorophyll a alteration in
these anoxic sediments and the possible implications for palaeoproductivit
y studies. Excellent preservation of pigments is indicated by high total pi
gment concentrations, and the presence of labile compounds such as chloroph
yllide a. The lack of systematic down core changes in both the total pigmen
t concentration and the chlorin composition indicates that no detectable al
teration of the pigment composition has occurred during the past 157 years.
The sedimentary pigment composition is the result of processes occurring i
n the water column, or within few months after deposition. Chlorophyll deri
vatives corresponding to different diagenetic processes have distinct down
core profiles. Profiles of compounds related to grazing activity steryl pyr
ophaeophorbide esters (SPE) and pyrophaeophytin a, are very similar. In con
trast, dephytylated compounds (chlorophyllide a and phaeophorbide a), which
are related to chlorophyllase activity during the degradation of ungrazed
diatom cells, show an independent pattern. Quantifying pigment composition
in Saanich Inlet sediments can help constrain processes regarding the trans
port of algal pigments to the sediments. Copyright (C) 2000 Elsevier Scienc
e Ltd.