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. 

Figure 6.11. A. Saturation state of seawater with respect to aragonite as a function of sulfate reduction. Based on general model of Ben-Yaakov (1973), updated by using pK a values and total ion activity coefficients of Millero (1982). B. Observed saturation state of Mangrove Lake, Bermuda pore waters with respect to calcite.

Orem, W.H., Hatcher, P.G, and Spiker, E.C. (1986) Dissolved organic matter in anoxic pore waters from Mangrove Lake, Bermuda. Geochim. Cosmochim. Acta 50, 609-618. 

Canfield D. E., Boudreau B. P., Mucci A., and Gundersen J. K. (1998) The early diagenetic formation of organic sulfur in the sediments of Mangrove Lake, Bermuda. Geochim. Cosmochim. Acta 62(5), 767-781. 

FIGURE 2. NMR spectra of humin isolated from various depth intervals in cores from two peats. The Everglades peat was collected from a sawgrass area in Conservation District lA west of Fort Lauderdale, Florida. The peat core from Mangrove Lake, Bermuda, was collected and described by Hatcher (1978). 

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. 

A similar resistance is noted with regard to diagenetic or microbial alteration. Recent studies of the whole sapropel and humin as a function of depth in Mangrove Lake have conclusively shown that the humin is selectively preserved during diagenesis and that labile substances such as lipids, carbohydrates, and proteins are decomposed and lost (Hatcher et al., 1983b). 

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. 

It is strikingly apparent that all spectra of aquatic kerogen are predominantly aliphatic with a major peak centered at 30 ppm. This peak is also the most intense peak in the spectrum of humin from Mangrove Lake also shown in Figure 9. Paraffinic structures of the type shown to be present in... 

FIGURE 9. C NMR spectra of algal kero-gens and boghead coals from locations described by Hatcher (1980). The spectrum of humin from Mangrove Lake, Bermuda, is also shown. 

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... 

Big Soda Lake, Mangrove Lake), interferring carotenols were removed via phase separation into 90% aqueous methanol (25-26). 

Figure 5. Electronic absorption spectra, (a) bacteriopheo-phytin-a(so1id) and the dioxy-dideoxo derivative (dashed) obtained following reduction with sodium borohydride and (b) the crude extract of Mangrove Lake (Bermuda) sapropel.

The content of aromatic carbon varies considerably in marine and estuarine humic acids, but is, in all cases, greater than that of Mangrove Lake humic acids. This is probably a reflection of the greater contribution of vascular plant-derived material which can be expected to provide lignin-like components rich in aromatic structures. Note that the humic acids from fluvial sediments of the Potomac River are the most aromatic. Peaks at 150 and 55 ppm are characteristic of oxygen-substituted aromatic carbons typically associated with lignin of vascular plants. Humic acids from New York... 

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. ... 

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