Marine organic matter structure

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. 

The difference in aromaticity between coal and crude oil is, therefore, predominantly a result of the base materials marine organic matter (like fats and amino adds), as a consequence of the base structures present, are rich in hydrogen and form crude oil containing materials of predominantly aliphatic structure terrestrial plants, characterized by a higher carbon content and greater aromaticity, lead to coals with a high proportion of aromatics. 

Pulleman M, Jongmans A, Marinissen J, Bouma J (2006) Effects of organic versus conventional arable farming on soil structure and organic matter dynamics in a marine loam in the Netherlands. Soil Use Manage 19 157-165... 

The fate of organic matter in the marine environment is largely related to its molecular structure, as this determines chemical reactivity. Compoimds characterized by high concentrations in seawater and the sediments typically have slow loss rates relative to their production. These compounds tend to exhibit low chemical reactivity in the marine environment and can persist in seawater fiar thousands of years. Conversely, compounds with low concentrations typically have high loss rates relative to their production. Their high reactivity is generally due to rapid biotic uptake and transformation, leading to turnover times that are on the order of minutes to days. Thus, to imderstand... 

Marine chemists have had limited success in characterizing the molecular structure of organic matter, particularly for the dissolved compounds. Chemical analysis usually starts with the isolation of POM from DOM using a filter with a 0.2-p,m pore size. This is generally followed by elemental analysis. More sophisticated approaches involve structural analysis, but this is usually limited to detection of functional groups or broad classes of compounds. 

Johansson C, Pavasars I, Boren H, Grimvall A, Dahlman O, Morck R, Reimann A (1994) A Degradation Procedure for Determination of Halogenated Structural Elements in Organic Matter from Marine Sediments. Environ Int 20 103... 

As discussed in Section V, the spectrum of substrates and substrate proxies currently used to measure enzyme activities in marine systems is limited and most likely does not adequately represent the macromolecules actually available to aquatic microbial communities. Despite progress in recent years, our knowledge of the molecular structure and composition of dissolved organic matter is still only rudimentary. Although carbohydrates constitute an estimated 25-50% of DOC in seawater (Benner et al., 1992),... 

Brandes, J. A., Lee, C., Wakeham, S., Peterson, M., Jacobsen, C., Wirick,S., and Cody, G. (2004). Examining marine particulate organic matter at sub-micron scales using scanning transmission X-ray microscopy and carbon X-ray absorption near edge structure spectroscopy. Marine Chem. 92,107-121. 

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