Origin, Composition, and Microbial Utilization of Dissolved Organic Matter

Abstract

There are two principal sources of organic matter in aquatic environments, living (biomass) and nonliving (detritus) (Odum and Cruz, 1963; Wetzel, 1983). It has long been noted that nonliving organic matter plays an important role in the structure and function of aquatic ecosystems (Krogh and Lange, 1932; Birge and Juday, 1934; Ohler 1934; Odum, 1963; Saunders, 1977). The detritus food chains were established along parallel lines with the classical phytoplankton-zooplankton grazing food chains. Wetzel et al. (1972) have developed a detailed scheme and model for the detritus food chain and have emphasized its fundamental differences from the classical grazing food chain. The nonpredatory loss of organic matter was found to be essential for understanding the whole aquatic ecosystem. Detrital organic matter tends to accumulate in aquatic environments until a quasi equilibrium is attained. This equilibrium is regulated by many environmental processes, such as decomposition, utilization, aggregation, and sedimentation.