| Abstract
| - This paper represents a successful laboratory-scalephotolysis of soil-bound tetra- to octachlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in olive oil. Theirradiation source consisted of two blacklight lamps emittinglight at a near-ultraviolet range. Samples used in theexperiments included pure 1,2,3,4,6,7,8-heptachlorodibenzofuran, PCDD/F extract made of a wood preservative(chlorophenol product Ky 5), and soil that was highlycontaminated with PCDD/Fs. Degradation of 1,2,3,4,6,7,8-heptachlorodibenzofuran dissolved in olive oil proceededrapidly with a first-order reaction half-life of 13 min. Irradiationof a soil sample resulted in an 84% reduction in PCDD/Ftoxicity equivalent (I-TEQ) in 17.5 h. A more completedegradation of soil-bound PCDD/Fs was achieved afterextraction of the soil with olive oil. The oil was effectivein solubilizing PCDD/Fs. After one extraction at roomtemperature, only 9% of I-TEQ remained in soil. Irradiationof the resulting extract reduced toxicity of the extract by99%, and even the highly chlorinated congeners octachlorodibenzo-p-dioxin and octachlorodibenzofurandegraded easily (97 and 99% degradation, respectively).Photodegradation byproducts found included diphenyl etherand small amounts of dechlorination products, whichwere mainly nontoxic PCDD/Fs. Degradation was probablymediated by light absorption of unsaturated fatty acidsand phenolic compounds in olive oil, leading to sensitizedphotolysis of PCDD/Fs.
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