Oxygen exposure time

Hartnett, H. E., Keil, R. G., Hedges, J. I., and Devol, A. H. (1998). Influence of oxygen exposure time on organic carbon preservation in continental margin sediments. Nature 391, 572-574. 

Due to the variability in redox conditions commonly found in nearshore systems, the term diagenetic oxygen exposure time was proposed as an indicator for organic matter preservation based on the amount of time sinking POM resides in the oxic porewaters of sediments. 

Fig. 3.25 Inverse relationship between carbon content of sediments (normalized to grain surface area) and exposure time to oxygen (after Gelinas et al. 2001). Oxygen exposure time (OET) = (depth of 02 penetration in sediment pore waters)/(sediment accumulation rate). Ctotaloiganic (mgm 2) = —0.161ogeOET + 1.28 and Cnoll protein (nignE2) = -0.0431ogeOET + 0.32 (r2 = 0.96 for both OET measured in years). Low OETs are typical of coastal sediments and high OETs of deep-sea sediments.

Hartnett, H.E., Keil, R.G. Hedges, J.I. and Devol, A.H. (1998) Influence of Oxygen Exposure Time on Organic Carbon Preservation in Continental Margin Sediments. Nature, 391, 572—574. 

This particularly interesting spectrum shows that, in this case, the oxygen exposure time causes the disappearance of a species, marked by a peak at 400°C, apparently to the benefit of the species corresponding to the peak located around 500°C. 

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