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Environmental fate & pathways

Phototransformation in water

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Conclusion (direct photodegradation - water): Direct photolysis will not contribute to the degradation of DTDP in the aquatic environment because it does not absorb light at wavelengths >290 nm, i.e., in the range that contribute to this process.

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Direct photochemical degradation in water occurs through the absorbance of solar radiation by a chemical substance. If the absorbed energy is high enough, then, in the resultant excited state, the chemical may undergo a transformation. A prerequisite for direct photodegradation is the ability of one or more bonds within a molecule to absorb ultraviolet (UV)/visible light in the 290 to 750 nm range. Light wavelengths longer than 750 nm do not contain sufficient energy to break chemical bonds, and wavelengths below 290 nm are shielded from the earth by the stratospheric ozone layer. An approach to assessing the potential for DTDP to undergo direct photochemical degradation is to assume that degradation will occur in proportion to the amount of light wavelengths >290 nm absorbed by DTDP molecules (Zepp and Cline, 1977). DTDP does not absorb light within a range of 290 to 750 nm.