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Case Study in Environmental Chemistry....
Case Study 3: Photolysis of Terbufos
Authors: Sarunya Hengpraprom and Cindy Lee, Environmental Engineering and Science, Clemson University.
Abstract : This case study considers the rate at which exposure to sunlight can transform a pesticide known as terbufos. Transformation of a contaminant by photolysis will change its behavior in a given situation. In some cases, a product of photolysis is just as toxic or more toxic than the parent compound. In other cases, the products of photolysis are rendered nontoxic and the transformation can be considered beneficial. The experiment described in this case study produced some of the first basic kinetics data available to evaluate the importance of photolysis as a process to remove terbufos from the environment. For more detailed information about this research, see Lee, C. M.; Anderson, B.; and Elzerman, A. W. 1999. Photochemical oxidation of terbufos. Environmental Toxicology and Chemistry. 18(7):1349-1353.
For further detail choose the appropriate section
Quiz
1. Transformation of organic contaminants will always result in less toxic products.
True or false
2. The wavelength of light is defined by
a. the distance between minima.
b. the distance between maxima.
c. the distance between atoms in a bond.
3. The organisms most acutely affected by the toxicity of terbufos are
a. bees.
b. fish.
c. reptiles.
d. mammals.
4. The mathematical expression describing the kinetics of photolysis includes
a. indirect photolysis.
b. direct photolysis.
c. both a and b.
d. neither a nor b.
5. Which transformation processes can lead to a wide variety of products?
a. hydrolysis
b. oxidation
c. biodegradation
d. reduction
6. Terbufos is not likely to be found in groundwater because of its
a. use as a pesticide.
b. molecular weight.
c. hydrophobicity.
d. small Kow.
7. Photolysis is not a significant transformation process for terbufos because it has a slow photolysis rate.
True or false.
8. Direct photolysis requires the compound to
a. interact with an intermediate.
b. absorb radiation.
c. react with a photosensitizer.
d. react in the dark.
9. Quantum yield provides information about
a. molar absorptivity.
b. wavelength.
c. frequency.
d. efficiency
10. Which instrument is used to measure the absorption spectrum?
a. gas chromatograph
b. UV-visible spectrophotometer
c. atomic absorption spectrometer
d. mass spectrometer