Organic matter derived from different source materials has distinctive chemical characteristics associated with those materials. Interactions among organic matter and the minerals and inorganic constituents in soil can result in the removal and fractionation of organic matter, altering the composition and reactivity of the dissolved organic carbon (DOC). Hydrologic conditions define the flow path and control the rate of transport of DOC within the system. The nature, distribution, and reactivity of organic matter in a given system is determined, to a large extent, by the strength and nature of interactions among the various components of the environment. Includes 24 references, tables, figures.