Humic material/substances marine

Other studies of humic substances using pyrolysis were done for evaluating the seasonal variations in humic materials [10] in different soils, for the analysis of marine deposits [11], the analysis of composts [12] or of degraded lignins [3]. 

Gillam, A. H. and Wilson, M. A. (1983). Application of C NMR spectroscopy to the structural elucidation of dissolved marine humic substances and their phytoplankton precursors. In Aquatic and Terrestrial Humic Materials (R. F. Christman and E. T. Gjessing, eds.) Ann Arbor Science, Ann Arbor, MI, pp. 25-36. 

X-ray spectra of phosphorus in natural organic molecules. The P NEXAFS spectroscopic studies conducted on isolated humic substances and soil organic molecules indicate that the primary form of P is phosphate and phosphonate (Fig. 24 Myneni and Martinez 1999). When compared to humic substances from soil systems, the fluvial humic substances exhibit phosphonate as one of the important components. However, phosphonate constitutes only a minor fraction of total P in humic substances. Soil samples also exhibit features that correspond to polyphosphate. Another study conducted using NEXAFS spectroscopy at the P absorption edge suggested that marine sediments and humic materials do not exhibit phosphonate and the P NEXAFS spectra of these samples more closely resembled that of hydroxyapatite (Vairavamurthy 1999). 

Sieburth, J. McN. and Jensen, A., 1968. Studies on algal substances in the sea. I. Gelb-stoff (humic material) in terrestrial and marine waters. J. Exp. Mar. Biol. Ecol., 2 174-189. 

Figure 3 summarizes the inputs and cycling of DOM in the sunfit upper layer of the surface ocean, the photic zone. Possible sources of DOM in the ocean include both river inputs and in situ production by phytoplankton. DOM in the marine environment was originally regarded as a complex mixture of both terrestrial material and marine-derived humic substances from phytoplankton... 

Burdon542 has surveyed the current hypotheses for the structure of humic substances and has concluded that the various products from chemical degradations and NMR data are all consistent with their being mixtures of plant and microbial materials and their microbial degradation products. The examination of soil carbohydrates, proteins, lipids, and aromatics supported this view the presence of colour, fluorescence, ESR signals, mellitic acid, and other features do not contradict it. Regarding the Maillard reaction, some free monosaccharides and the necessary amino species are present in soil, so it may proceed, but only to a small extent it is not a major process. However, in marine environments, the relative abundance of carbohydrates and proteins makes them more probable precursors of humic substances than lignin or polyphenols. 

Further work on differentiating marine and coastal runoff humic substances was hindered by the lack of suitable isolation techniques for the marine material since concentrations in the open sea rarely exceed 0.25 mg/ L. Sorption of marine humic substances from seawater onto solid phases is now a standard technique and can be used to extract gram quantities of marine humic substances for chemical and physical studies (see Aiken, Chapter 14). Sieburth and Jensen (1968) first used rolled nylon stockings as an adsorbant but the method suffered from contamination. Kerr and Quinn (1975) used a specially treated charcoal and obtained quantitative recovery of the dissolved colored substances in seawater. Riley and Taylor (1969) introduced the use of cross-linked polystyrene resins, specifically Amberlite XAD-2. This polymer is now the most widely used for open-ocean work (Stuermer and Harvey, 1974 Bada et al., 1982 Harvey et al., 1983) and in estuaries (Mantoura and Riley, 1975). These isolation methods have made available sufficient quantities of seawater humic substances for detailed chemical studies. 

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