Sapropel from Mangrove Lake

Knicker, H., and Hatcher, P. G. (2001). Sequestration of organic nitrogen in the sapropel from Mangrove Lake, Bermuda. Org. Geochem. 32, 733-744. 

A similar selective preservation was observed in peat as discussed earlier where an additional component, lignin, was also preserved selectively. However, the major component of humin from Everglades peat was the paraffinic component that also appeared to be selectively preserved relative to the polysaccharides. It is interesting to note the similarity between the spectra of delignified humin at the 15-16 cm interval in peat (Fig. 5) and that of the algal sapropel from Mangrove Lake at the 272-290 cm interval. The similarity between these two spectra infers that similar structural entities are present in these two depositional environments, and it is probable that the two similar structural components are from a common source, namely, algal and microbial remains. 

Humic isolates from different layers of an organic matter rich algal sapropel from Mangrove Lake, Bermuda, have been analyzed using solid-state N NMR in order to reveal chemical structural interrelationships that allow delineation of diagenetic pathways. ... 

The similarity between the various spectra in Figure 9 should be underscored because such spectral similarities reinforce arguments concerning the origin and formation of algal kerogen. In many respects, the spectrum of the Miocene sapropelic coal is nearly identical to that of humin from Mangrove Lake, Bermuda. The only differences appear to be in the relative amounts of... 

FIGURE 6. C NMR spectra of samples of whole sapropel, humin, and hydrolyzed humin from a core of Mangrove Lake, Bermuda. The whole sapropels are from a core collected in 1982. The humin was from a core collected in 1971 (Hatcher, 1978) and is characteristic of humin from all depths in the sapropel. 

Figure 11. This graph shows how both the concentrations and isotopic compositions of snlfate and snffide evolve with sediment depth in the sapropelic sediments of Mangrove Lake, Bermnda. Whereas the isotopic compositions of snlfate and sulfide appeared to evolve as in a Rayleigh distillation model (see Fig. 10), snch a model is inappropriate for determining fractionations. This is because marine sediments are open with respect to the exchange of chemical species. See text for details. Data are replotted from Canfield et al. (1998b).

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