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United States Department of Agriculture

Agricultural Research Service

Title: Sorption, Mobility and Fate of 1,3,7,8-Tetrachlorodibenzo-P-Dioxin in Soils and Sand

Authors
item Hakk, Heldur
item Casey, Frances - NORTH DAKOTA STATE UNIV.
item Larsen, Gerald

Submitted to: Organohalogen Compounds
Publication Type: Proceedings
Publication Acceptance Date: June 12, 2002
Publication Date: September 1, 2002
Citation: Hakk, H., Casey, F., Larsen, G.L. 2002. Sorption, mobility and fate of 1,3,7,8-tetrachlorodibenzo-p-dioxin in soils and sand. Organohalogen Compounds. 57:301-304.

Interpretive Summary: Batch experiments indicated that the relatively non-toxic dioxin, 1,3,7,8-TCDD readily moves from being dissolved in water to being absorbed to the various soil types tested (loam, sandy loam, silt loam, clay loam, and sand) and clay (kaolin and bentonite). Column studies showed only limited amounts of the dioxin can move through these various soils types, including the sand (0-1.4%). However, significant amounts did move through the loam (26.8%) and silt loam (24.9%) soil columns. Additionally, except for the sand, the elution peak of the dioxin was very rapid (i.e. faster than something not being absorb by the soil), which indicated that 1,3,7,8-TCDD might have followed preferred pathways (e.g. macropores, cracks, root channels, worm holes, funnel flow, and instability of wetting front) in its movement through the various soil columns. This indicates that 1,3,7,8-TCDD can be leached to groundwater. Generally, the 1,3,7,8-TCDD was significantly redistributed through the soil column profile of the various soil types. It was found that 39.6%-101% of the applied 1,3,7,8-TCDD was retained by the various soils. Most was absorbed to the top three cm (78.8¿99.7%), except for the clay loam where it was distributed throughout the column. The first centimeter of the various soils contained 11.0-95.4% of the dioxin. Organic solvents could extract most of the dioxin (54.9-87.1%) from these first centimeters, while 2.2-11.9% of the dioxin remained nonextractable.

Technical Abstract: Batch experiments indicated that 14C from 1,3,7,8-TCDD readily partitioned out of the dissolved phase into the sorbed phase in the various soil types tested (loam, sandy loam, silt loam, clay loam, and sand) and clay (kaolin and bentonite). Column studies showed only limited 14Cin the effluent for most of the soil types including the sand (0-1.4%). However, significant amounts 14C were eluted from the loam (26.8%) and silt loam (24.9%) soil columns. Additionally, except for the sand, the elution peak of 14C was very rapid (i.e. 0.2-0.32 pore volumes), which indicated that 1,3,7,8-TCDD might have followed preferred pathways (e.g. macropores, cracks, root channels, worm holes, funnel flow, and instability of wetting front) in its movement through the various soil columns. This indicates that 1,3,7,8-TCDD can be leached to groundwater. Generally, 14C from 1,3,7,8-TCDD was significantly redistributed through the soil column profile of the various soil types. After the combustion analysis for 14C, it was found that 39.6%-101% of the applied 1,3,7,8-TCDD was retained by the various soils. Most of the 14Cwas sorbed to the top three cm (78.8¿99.7%), except for the clay loam where 14C was distributed throughout the column. The first centimeter of the various soils contained 11.0-95.4% of the 14C. Toluene extracts of these first centimeters contained most of the 14C (54.9-87.1%), while 2.2-11.9% of the 14C was nonextractable. 1,3,7,8-TCDD was virtually the only compound observed by TLC(1,3,7,8-TCDD, Rf=0.69).

Last Modified: 4/18/2014
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