Humic material/substances chlorination

Some researchers pointed out that extracted humic materials might cause problems for the extraction and photolysis of probe (pollutant) molecules. First, the extraction efficiency may decrease, and second, humics are known to quench photochemical reaction. For example, Zepp R..G. et al. (1975) suggested that phenolic humic substances present on most inland waters could inhibit free radical chain reactions. Thus, quantum yields for direct photolysis of chlorinated compounds in the aquatic environment are not likely to exceed unity. 

Myneni SCB, Brown JT, Martinez GA, Meyer-Ilse W (1999b) Imaging of humic substance macromolecular structures in water and soils. Science 286 1335-1337 Myneni SCB (2000) X-ray and vibrational spectroscopy of sulfate in earth materials. Rev Min 40 113-172 Myneni SCB (2002) Formation of stable chlorinated hydrocarbons in weathering plant material. Science 295 1039-1041... 

The most important humic substances in water are the lower-molecular-mass fulvic acids. These species tend to chelate Fe " ion, producing a yellow material called gelbstoffe (German for yellow stuff), which is responsible for much of the undesirable color found in some water. Metal ions bound with fulvic acid are hard to remove from water and, since iron is a very undesirable water impurity, drastic measures such as destruction of the fulvic acid with chlorine may be required to remove the chelated iron. Figure 3.14 illustrates a typical fulvic acid molecule. 

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