Photooxidation and photoreduction on soil surfaces
- Univ. of Nevada, Reno (USA)
Photochemical reactions of xenobiotics on soil surfaces are restricted to the top 1-2 mm of soil. However, photolysis can be a significant transformation pathway in soils, particularly for those compounds which are deposited from the vapor phase. Photooxidation on soil surfaces can proceed either by direct photolysis, or by indirect reactions. Singlet oxygen, through an indirect process, is produced on irradiated soil surfaces and reacts with a variety of compounds, particularly sulfides. Other less well-defined oxidations are also observed which causes the irradiated air-soil interface to be highly oxidized. Photoreduction processes on soil surfaces, including dechlorination and nitroreduction, are also observed. Addition of organic solvents enhances this process, although movement of xenobiotics to the light-exposed surface from subsurface regions can also cause photolysis rate enhancements. 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), when irradiated on 0.5 mm deep soils degrades until the light exposed fraction (30%) is lost, and further loss is not observed. If 1% hexadecane is added to the soil prior to exposure, continued photochemical loss of TCDD from the soil is observed, suggesting that movement into the light exposed upper layer is occurring.
- OSTI ID:
- 7169544
- Report Number(s):
- CONF-8904176--
- Journal Information:
- American Chemical Society, Division of Environmental Chemistry, Preprints; (USA), Journal Name: American Chemical Society, Division of Environmental Chemistry, Preprints; (USA) Vol. 29:1; ISSN ACEPC; ISSN 0093-3066
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
540200* -- Environment
Terrestrial-- (1990-)
540210 -- Environment
Terrestrial-- Basic Studies-- (1990-)
CHEMICAL REACTIONS
CHEMISTRY
DATA
DATA ANALYSIS
EXPERIMENTAL DATA
INFORMATION
MEASURING INSTRUMENTS
MEASURING METHODS
NUMERICAL DATA
PHOTOCHEMISTRY
REDOX REACTIONS
SOIL CHEMISTRY
SOILS