Marine organic matter extraction

Our explanation for the absence of odd-carbon preference in marine organic matter is based on the fact that this absence is also seen in extracts of marine organisms and of bacterial cells. Our evidence from slope sediments suggests that the strong bacterial impression on normal marine, deep water sedimentary organic matter produces both features. 

After several decades of research, fundamental aspects of the chemical composition and structure of marine organic matter remain elusive. Advances in the chemical characterization of marine organic matter are, in large part, dependent on the development of quantitative methods for its concentration and isolation from seawater. Each of the major methods currently used for the isolation of marine DOM recovers around one-third of the DOM in seawater (solid-phase extractions, using XAD resins or C18 adsorbents, and ultrafiltration). A coupled reverse osmosis-electrodi-alysis method has recently been used to recover an average of 75% 12% of marine DOM from 16 seawater samples however, the method has emerged too recently to have been well tested at this time. 

Mopper, K., Stubbins, A., Ritchie, J. D., Bialk, H. M., and Hatcher, P G. (2007). Advanced instrumental approaches for characterization of marine dissolved organic matter Extraction techniques, mass spectrometry, and nuclear magnetic resonance spectroscopy. Chem. Rev. 107,419-442. 

Slauenwhite, D. E., and Wangersky, P. J. (1996). Extraction of marine organic matter on XAD-2 Effect of sample acidification and development of an in situ pre-acidification technique. Mar. Chem. 54,107-117. 

A variety of spectroscopic techniques have been applied to DOC isolated from seawater by cross-flow ultrafiltration or adsorption onto XAD resins. The two techniques isolate very different organic fractions from seawater. Hydrophobic fractions (such as marine humic material) are isolated on XAD resins [48], whereas the organic matter extracted by ultrafiltration is retained primarily on the basis of its molecular size and shape [49], resulting in isolates rich in nitrogen and carbohydrates (polysaccharides). Nuclear magnetic resonance (NMR) spectroscopy has proven successful in distinguishing between the specific structures of XAD-bound humics and the carbohydrates concentrated into colloidal size fractions. 

Pierce RH Jr, Felbeck GT Jr (1972) A comparison of three methods of extracting organic matter from soils and marine sediments. In Povoledo D, Golterman HL (eds) Humic Substances. Center for Agriculture Publication and Documentation, Wageningen, Netherlands, pp 217-232... 

At present, soil derived humic matter and fulvic acids extracted from freshwater are available commercially and are commonly used to test techniques for DOM detection and also used as model compounds for trace metal chelation studies. The results obtained using these model compounds are frequently extrapolated to the natural environment and measurements on "real" samples provide evidence that this DOM is a good model compound. In the past, some investigators also made available organic matter isolated from marine environments using C18 resins. While these compounds come from aquatic sources, this isolation technique is chemically selective and isolates only a small percentage of oceanic DOM. Reference materials are not currently available for these compounds, which inhibits study of the role they play in a variety of oceanographic processes. 

Simjouw, J-P., Minor, E. C., and Mopper, K. (2005). Isolation and characterization of estuarine dissolved organic matter Comparison of ultrafiltration and Cig solid-phase extraction techniques. Marine Chemistry 96(3—4), 219—235. 

The ASE technique has also been compared — to a lesser extent, however — with ultrasound-assisted extraction (USE) and found to provide better [49,59,81] or at least similar results [31,85,109] in most cases. The advantages of ASE over USE are similar to those of the former in relation to Soxhlet extraction, i.e. increased throughput, automatability and decreased solvent consumption. While ASE extraction times are also short relative to USE, this is not the most salient advantage as USE times are also fairly short. The reduced consumption of solvents is indeed a major advantage, particularly in cases such as the extraction of organic pollutants from marine particulate matter, where... 

In addition to direct extraction of humic substances, the amount of humic substances has been estimated by subtracting the amount of biochemicals (sum of lipids, amino acids or proteins, and carbohydrates) from the total organic matter in the sediments (Kemp and Johnston, 1979). In this chapter, this difference is called nonbiochemicals, although no doubt there is much overlap between nonbiochemicals and extracted humic substances. As shown in Table 2, nonbiochemicals amount to 42-58% of the total organic matter in two Japanese lake sediments, but in the Great Lake (North America) sediments nonbiochemicals amount to 70-79% of the total organic matter on average. The latter values are close to those observed for marine sediments (Ishiwatari, 1979). 

The amounts of hydrolyzable organic matter and humic substances extracted by alkaline aqueous solutions decrease with the burial depth of a sediment. This is demonstrated by Hue et al. (1980) on Black Sea sediments where the organic matter is mainly autochthonous (Fig. 12). Boudou (1981), who studied diagenesis of terrestrial organic matter deposited in marine deltaic sediments, also noted this decrease (Table 8). The amount of hydrolyzable organic matter decreases very rapidly as a function of depth. Humic substances disappear more slowly, and their decrease can be followed dur-... 

In this chapter, we consider humin to be the residue after successive extraction of sediments by benzene/methanol to remove lipids, dilute acid IN HCl), and 0.5N NaOH. In marine sediments, further treatment with concentrated HF/HCl (1 1 v/v) is required to concentrate the organic matter by removal of mineral matter. This treatment will partially or totally hydrolyze polysaccharides and proteins while probably having little effect on the humic material (Hatcher et al., 1983a). 

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