Redox conditions, reconstruction

The preservation of organic matter in coastal and estuarine sediments is believed to be principally controlled by productivity, sedimentation accumulation rate, bottom water and sediment redox conditions, and sorption as a function of specific surface area of sediments (see review, Hedges and Keil, 1995). In this section the focus will be primarily on factors controlling preservation or organic matter in estuarine sediments the use of chemical biomarkers for historical paleo-reconstruction of past estuarine environments is discussed in chapter 15. 

Repeta et al., 1989 Chen et al., 2001), while bacteriochlorophylls-c and d can be found in other Chlorobium spp. As a result of their linkages to environmental redox conditions bacteriochlorophylls have been successfully used as an index for reconstructing paleore-dox in aquatic systems (Chen et al., 2001 Squier et al., 2002, 2004)—more details on this in chapter 15. 

Surface reconstruction has been earlier observed and reported in the literature [116]. Sequential reductive and oxidative thermal treatment usually leads to bulk transition from CoOx + La203 to LaCo03, respectively. On the other hand, the restoration of the perovskite structure is not observed under severe conditions at higher temperature. In those temperature conditions, the sintering of Co crystallites leads to irreversible redox cycle with the preferential formation of Co304 under lean conditions. 

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