Chromophoric dissolved organic matter CDOM

Humic substances represent a large fraction of what is termed chromophoric dissolved organic matter (CDOM) in aquatic systems around the world. Aquatic humic substances can be further categorized as fulvic acids, humic acids, and humin based on theis solubility in acid and base solutions. 

DOM, and in particular dissolved humic substances give, depending on their concentration, a yellowish or brown colour to the natural waters. To underline the fact that the light-absorbing components, and, thus, those that are photochemically active, are also responsible for the colour, the term coloured (or chromophoric) dissolved organic matter (CDOM) [24,25] has been proposed for use in environmental photochemistry literature, and will be used here. 

Steinberg, D. K., Nelson, N. B., Carlson, C. A., andPrusak, A. (2004). Production of chromophoric dissolved organic matter (CDOM) in the open ocean by zooplankton and the colonial cyanobacterium Trichodesmium spp. Mar. Ecol. Prog. Ser 267, 45—56. 

N.V. Blough, R. Del Vecchio (2002). Chromophoric dissolved organic matter (CDOM) in the coastal environment. In D.A. Hansell and C.A. Carlson (Eds). Biogeochemistry of Marine Dissolved Organic Matter (pp. 509-546), Academic Press. 

The depth of vertical mixing may also be directly affected by increased UVR. In many systems (particularly fresh waters), the major component responsible for determining UVR penetration, chromophoric dissolved organic matter (CDOM), is also the primary absorber of visible radiation. Absorption of solar radiation by CDOM results in near-surface heating and shallow stratification [10,11]. However, CDOM absorbance is not constant, due to photobleaching by UVR [12]. As CDOM bleaches, there is deeper penetration of solar radiation and less pronounced surface heating, allowing deeper mixed layers to develop ([13] also see Chapters 3 and 6). 

Kieber, R. J., Whitehead, R.F., Reid, S. N., Willey, JD., and Seaton, P.J. (2006). Chromophoric dissolved organic matter (CDOM) in rainwater, southeastern North Carolina, USA. J. Atmos. Chem., 54,21 1. 

Kieber, R.J., WiUey, J.D., Whitehead, RJ and Reid, S.N. (2007). Photobleaching of chromophoric dissolved organic matter (CDOM) in rainwater. /. Atmos.Chem., 58, 219-235. 

Chen, R.F., Gardner, G.B., Huang, W., and Peri, F. (2007). Chromophoric dissolved organic matter (CDOM) dynamics in the Hudson River Plume. ASLO, Santa Fe, February... 

Clark, C.D., Litz, L.R, and Grant, S.B. (2008). Salt marshes as a source of chromophoric dissolved organic matter (CDOM) to Southern California coastal waters. Limnol. Oceanogr., 53(5), 1923-1933. 

---