ARS | Publication request: SORPTION, MOBILITY AND FATE OF 1,2,7,8-TETRACHLORODIBENZO-P-DIOXIN IN SOILS AND SAND.

Submitted to: Organohalogen Compounds
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 1, 2003
Publication Date: January 1, 2003
Citation: Larsen, G.L., Casey, F., Fan, Z., Hakk, H. 2003. Sorption, mobility and fate of 1,2,7,8-tetrachlorodibenzo-p-dioxin in soils and sand. Organohalogen Compounds. 61:397-400.

Interpretive Summary: Batch experiments indicated that the relatively non-toxic dioxin, 1,2,7,8-TCDD readily moves from being dissolved in water to being absorbed to the various soil types tested (loam, clay loam, sandy clay loam, siltloam, silty clay loam, and sand) and clay (kaolin and bentonite). Column studies showed significant amounts did move through the clay loam (22%), sandy clay loam (41.2%), silty clay loam (15%), and silt loam (18%) soil columns. Limited amounts of the dioxin moved through the loam (0.2%) and sand soil columns(0.4%). Except for the sand and 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 1,2,7,8-TCDD might have been bound to colloid particles which facilitated its movement through the various soil columns. This indicates that 1,2,7,8-TCDD can be leached to groundwater. It was found that 41.7%-117% of the applied 1,2,7,8-TCDD was retained by the various soils. Most of the 1,2,7,8-TCDD was distributed throughout the column in the various soil columns except for the loam column where most was sorbed to the top three cm (110%). Organic solvents could extract most of the dioxin (36.2-95.7%) from these first centimeters, while 2.1-32.1% of the dioxin remained nonextractable. 1,2,7,8-TCDD was virtually the only compound observed, but minor metabolites were detected (0.1-10.1%).

Technical Abstract: Batch experiments indicated that 14C from 1,2,7,8-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, silty clay loam, and sand) and clay (kaolin and bentonite). Column studies showed significant 14Cin the effluent for most of the soil types including the sand (15.1-41.2%). Limited amounts of 14C were eluted from the loam (0.6%) and sand (0.4%) soil columns. Additionally, except for the sand and sandy clay loam, the elution peak of 14C was very rapid (i.e. 0.18-0.30 pore volumes), which indicated that 1,2,7,8-TCDD might be binding to colloid particles allowing its rapid movement through the various soil columns. This indicates that 1,2,7,8-TCDD can be leached to groundwater. After the combustion analysis for 14C, it was found that 41.7%-117% of the applied 1,2,7,8-TCDD was retained by the various soils. Most of the 14C was distributed throughout the column in the various soil columns except for the loam column where most of the 14C was sorbed to the top three cm (110%). The first centimeter of the various soils contained 9.9-67.5% of the 14C. Toluene extracts of these first centimeters contained most of the 14C (36.2-95.7%), while 2.1-32.1% of the 14C was nonextractable. 1,2,7,8-TCDD was virtually the only compound observed, although, minor metabolites present (0.1-10.1%)as determined by TLC.