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United States Department of Agriculture

Agricultural Research Service

Title: Sorption, Mobility and Fate of 1,4,7,8-Tetrachlorodibenzo-P-Dioxin in Soils

Authors
item Larsen, Gerald
item Zhaosheng, Fan - NORTH DAKOTA STATE UNIV
item Casey, Francis - NORTH DAKOTA STATE UNIV
item Hakk, Heldur

Submitted to: Organohalogen Compounds
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 16, 2004
Publication Date: June 16, 2004
Citation: Larsen, G.L., Zhaosheng, F., Casey, F., Hakk, H. 2004. Sorption, mobility and fate of 1,4,7,8-tetrachlorodibenzo-p-dioxin in soils. Organohalogen Compounds. 66:2292-2296.

Interpretive Summary: Batch experiments indicated that the relatively non-toxic dioxin, 1,4,7,8-TCDD readily moves from being dissolved in water to being absorbed to the various soil types tested (loam, clay loam, sandy clay loam, siltloam, and silty clay loam) and clay (kaolin and bentonite). Column studies showed limited amounts of the 1,4,7,8-TCDD moved through the clay loam (0.64%), sandy clay loam (0.16%), silty clay loam (0.04%), silt loam (0.99%), and loam (0.61%)soil columns. Except for the sandy clay loam column, the elution peak of the dioxin was very rapid (i.e. faster than something not being absorb by the soil), which indicated that 1,4,7,8-TCDD might have been bound to colloid particles which facilitated its movement through the various soil columns. This indicates that a limited amount of 1,4,7,8-TCDD may be leached to groundwater. It was found that 77.0%-95.2% of the applied 1,4,7,8-TCDD was retained by the various soils. Most of the 1,4,7,8-TCDD was distributed through first three centimeters of the various soil columns in the various soil columns (59.9-83.7%) with first centimeter of the various soils containing 33.2-67.2% of the 1,4,7,8-TCDD applied. Organic solvents could extract most of the dioxin (36.2-95.7%) from the top centimeter of soil. 1,4,7,8-TCDD was the only compound observed in any of the organic solvent extracts.

Technical Abstract: Batch experiments indicated that 14C labelled 1,4,7,8-TCDD readily partitioned out of the dissolved phase into the sorbed phase in the various soil types tested (loam, clay loam, sandy clay loam, silt loam, and silty clay loam) and clay (kaolin and bentonite) had Kd values ranging from 0.16-0.30 [(mg/g)/(mg/L)](Freundlich adsorption) and 0.40-0.68 [(mg/g)/(mg/L)] (Linear adsorption). Column studies showed limited 14C labelled 1,4,7,8-TCDD in the effluent for all the soil types (0.04-0.99%). Additionally, except for the sandy clay loam, the elution peak of 14C was very rapid (i.e. 0.25-0.35 pore volumes), which indicated that 1,4,7,8-TCDD might be binding to colloid particles allowing its rapid movement through the various soil columns. This indicates that a limitted amount of 1,4,7,8-TCDD may be leached to groundwater. After the combustion analysis for 14C, it was found that 77.0%-95.2% of the applied 1,4,7,8-TCDD was retained by the various soils. Most of the 14C was sorbed in the first three centimeters of the column of the various soil columns (59.9-83.7%). The first centimeter of the various soils contained 33.2-67.2% of the 14C. Toluene extracts of these first centimeters contained most of the 14C (57.6-99.0%). 1,4,7,8-TCDD was the only compound observed. These results indicate that 1,4,7,8-TCDD is strongly sorbed to soil and is resistant to transformation.

Last Modified: 4/18/2014
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