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Environmental fate & pathways

Phototransformation in soil

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Reference
Endpoint:
phototransformation in soil
Type of information:
other: technical discussion
Adequacy of study:
supporting study
Study period:
not applicable
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data are gathered from several peer reviewed sources.
Qualifier:
no guideline followed
Principles of method if other than guideline:
A technical discussion is provided in the conclusion and executive summary.
Validity criteria fulfilled:
yes
Conclusions:
The direct photolysis of an organic molecule occurs when it absorbs sufficient light energy to result in a structural transformation. The absorption of light in the ultra violet (UV)-visible range, 110-750 nm, can result in the electronic excitation of an organic molecule. The stratospheric ozone layer prevents UV light of less than 290 nm from reaching the earth's surface. Therefore, only light at wavelengths between 290 and 750 nm can result in photochemical transformations in the environment.
A conservative approach to estimating a photochemical degradation rate is to assume that degradation will occur in proportion to the amount of light wavelengths >290 nm absorbed by the molecule. Hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics, <2% aromatics (D90) , contains hydrocarbon molecules that absorb UV light below 290 nm, a range of UV light that does not reach the earth's surface. Therefore, hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics, <2% aromatics, does not have the potential to undergo photolysis in water and soil, and this fate process will not contribute to a measurable degradative loss of this substance from the environment.
Executive summary:

The direct photolysis of an organic molecule occurs when it absorbs sufficient light energy to result in a structural transformation. The absorption of light in the ultra violet (UV)-visible range, 110-750 nm, can result in the electronic excitation of an organic molecule. The stratospheric ozone layer prevents UV light of less than 290 nm from reaching the earth's surface. Therefore, only light at wavelengths between 290 and 750 nm can result in photochemical transformations in the environment.

A conservative approach to estimating a photochemical degradation rate is to assume that degradation will occur in proportion to the amount of light wavelengths >290 nm absorbed by the molecule. Hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics, <2% aromatics (D90), contains hydrocarbon molecules that absorb UV light below 290 nm, a range of UV light that does not reach the earth's surface. Therefore, this substance does not have the potential to undergo photolysis in water and soil, and this fate process will not contribute to a measurable degradative loss of this substance from the environment.

Description of key information

Key value for chemical safety assessment

Additional information

The direct photolysis of an organic molecule occurs when it absorbs sufficient light energy to result in a structural transformation. The absorption of light in the ultra violet (UV)-visible range, 110-750 nm, can result in the electronic excitation of an organic molecule. The stratospheric ozone layer prevents UV light of less than 290 nm from reaching the earth's surface. Therefore, only light at wavelengths between 290 and 750 nm can result in photochemical transformations in the environment.

 

A conservative approach to estimating a photochemical degradation rate is to assume that degradation will occur in proportion to the amount of light wavelengths >290 nm absorbed by the molecule. Hydrocarbons, C12-C15, n-alkanes, isoalkanes, cyclics < 2% aromatics (D90) contains hydrocarbon molecules that absorb UV light below 290 nm, a range of UV light that does not reach the earth's surface. Therefore, this substance does not have the potential to undergo photolysis in water and soil, and this fate process will not contribute to a measurable degradative loss of this substance from the environment.