Source, Production, and Fractions of Dissolved Organic Matter

SOURCE, PRODUCTION, AND FRACTIONS OF DISSOLVED ORGANIC MATTER 

Organic forms of carbon, nitrogen, sulfur, and phosphorus (typically less than 0.7 pm in diameter) contribute to bulk DOM. Humic substances, 

FIGURE I Molecular weight distribution (thousands of daltons) of dissolved organic carbon in wet precipitation, throughfall, A and B horizon soil solution, and stream water at Hubbard Brook, New Hampshire. Source Adapted from McDowell (1982) and Cole et al. (1984). 

Concentration and Flux of Dissolved Organic Carbon and Nitrogen 

Synthesis of concentrations and fluxes of DOC and DON in precipitation, throughfall, and soil organic and mineral horizons are often reported in the published literature (Willey et al., 2000 Michalzik et al., 2001 Neff and Asner, 2001 Neff et al., 2002). Dissolved organic matter from these sources contributes DOM to groundwater and surface water. Leaf litter leachate is documented as a major source of DOC in the soil water of forested watersheds (Hongve, 1999) and in surface waters (Wetzel and Manny, 1972 McDowell and Fisher, 1976). However, specific quantitative allocation of DOC and DON from roots, leaf litter, and the forest floor in soil solution remains uncertain. 

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II. Source, Production, and Fractions of Dissolved Organic Matter 28... 

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