Sedimentary chlorophyll derivatives

Sedimentary Chlorophyll Derivatives. In order to unravel the bio-geochemistry of chlorophyll, a variety of depositional environments, each representing potentially different fossilized counterparts, require study. Though the present investigation stresses marine sediments, collected well beneath the photic zone in order to divorce detrital from viable photoautotrophic material, photic zone sapropels and peats have also been examined. 

The losses of magnesium and phytol through the combined effects of cellular senescence and predation (i.e. aerobic heterotrophy) in the water column lead to pheophytin-a and pheophorbide-a becoming the primary chlorophyll-a derivatives deposited in marine sedimentary environments. Though it is not known at present, the heterotrophic processes which cleave phytol more than likely also affect the 10-carbomethoxy group. Studies are underway to investigate the amounts of pyro-pheophorbides in water column detritus and surface sediments. 

Fig. 5. 9 Major anoxic sedimentary diagenetic routes for chlorophyll-a derivatives subsequent to those in Fig. 5.6 (after Barwise Roberts 1984 Baker Louda 1986 Louda et al. 1998, 2000).M= cations (e.g.Ni2+,V02+, Cu2+, GaOH2+).

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