Dissolved organic matter autochthonous sources

Recent investigations provide new insight on the structural chemistry of dissolved organic matter (DOM) in freshwater environments and the role of these structures in contaminant binding. Molecular models of DOM derived from allochthonous and autochthonous sources show that short-chain, branched, and alicyclic structures are terminated by carboxyl or methyl groups in DOM from both sources. Allochthonous DOM, however, had aromatic structures indicative of tannin and lignin residues, whereas the autochthonous DOM was characterized by aliphatic alicyclic structures indicative of lipid hydrocarbons as the source. DOM isolated from different morphoclimatic regions had minor structural differences. 

Supply of Dissolved Organic Matter to Aquatic Ecosystems Autochthonous Sources... 

Bertilsson, S., and Jones, J. B., Jr. (2003). Supply of dissolved organic matter to aquatic ecosystems Autochthonous sources. In Aquatic Ecosystems—Interactivity of Dissolved Organic Matter, Findlay, S. E. G., and Sinsabaugh, R. L., eds., Academic Press, Amsterdam, pp. 3-24. 

Figure 8.6 Major sources of dissolved organic matter (DOM) to estuaries, primarily composed of riverine inputs, autochthonous production from algal and vascular plant sources, benthic fluxes, groundwater inputs, and exchange with adjacent coastal systems. (Modified from Hansell and Carlson, 2002.)...

Detritus includes non-living particulate, colloidal, and dissolved organic matter, and metabolically size only affects rates of hydrolytic attack [31]. Inland aquatic ecosystems collect organic matter, particularly in dissolved forms, from terrestrial, wetland, and littoral sources in quantities that supplement if not exceed those produced autochthonously. Rates of utilization of that organic matter are slowed by a combination of chemical recalcitrance as well as displacement to anoxic environments. As a result, inland aquatic ecosystems are hetero-trophic and functionally detrital bowls, not algal bowls. 

The general pools of organic matter in estuaries can be divided into particulate (>0.45 pm) and dissolved (<0.45 pm) fractions (POM and DOM). The dominant living and nonliving (detritus) sources of organic matter to estuaries can be divided into allochthonous and autochthonous pools—sources produced outside and within the boundaries of the estuary proper, respectively. These pools can further be divided into heterotrophs and autotrophs. 

Riverine fluxes. Approximately 0.2 Gt each of dissolved and particulate OC are carried from land to sea annually by rivers (Ludwig et al., 1996). Much of this riverine organic matter appears to be soil derived based on its chemical characteristics (Meybeck, 1982 Hedges et al., 1994), although autochthonous sources may be important for the dissolved fraction (Repeta et al., 2002). It is now recognized that, on a global basis, riverine... 

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