In aquatic ecosystems and soil interstitial waters, dissolved organic material (DOM) is comprised of a heterogeneous mixture of organic compounds derived from plant and soil decomposition and leachate, degradation of microbial biomass, and microbial exudates. Organic material present in the solid phase of soils and sediments (SOM) is similarly complex, with variations not only in chemical composition, but also in the extent to which organic molecules are bound to minerals. The chemical characteristics and distribution of classes of organic compounds within DOM can be dynamic. For example, DOM quality can change seasonally with hydrologic drivers, such as snowmelt, or due to summertime algal blooms in lakes and streams. In contrast, changes in SOM may occur more slowly as soils and sediments age, a process historically referred to as humification.
Gabor, R., A Baker, D. McKnight, *M. Miller (2014): Fluorescence Indices and their Interpretation . In Aquatic Organic Matter Fluorescence, Coble, P.G., Lead, J., Baker, A., Reynolds, D.M., and Spencer, R.G.M., eds., Cambridge University Press , p. 303-339, isbn: 9781139897907.
This Paper/Book acknowledges NSF CZO grant support.