Black carbon-dominated PCDD/Fs sorption to soils at a former wood impregnation site.
The influence of black carbon (BC) on the sorption of 17 native polychlorinated-p-dibenzodioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) was studied in five soil samples from a sawmill site where wood used to be impregnated with chlorophenol preservatives. The presence of BC caused measured total organic carbon (TOC)-water distribution ratios (K(TOC)) to be a median factor of 51 (interquartile range 18-68, n=85) higher than modeled amorphous organic carbon (AOC)-water distribution ratios (K(AOC)). K(TOC) was a factor of 73+/-27 above K(AOC) for PCDFs (n=10) and a factor of 20+/-13 (n=7) for PCDDs. The reason for this difference is probably that attaining a planar configuration after sorption to BC is less thermodynamically favorable for PCDDs than for PCDFs. BC-water distribution ratios were calculated from K(TOC), K(AOC) and BC contents, and ranged from 10(9.9) (2,3,7,8-Tetra-CDD) to 10(11.5) l kg(-1) (Octa-CDF). More than 90% of the PCDD/Fs in the soil was calculated to be BC-sorbed. Dissolved organic carbon (DOC)-water distribution ratios were measured to be in the same order of magnitude as K(AOC). This study shows that strong sorption to BC should be included when assessing ecotoxicological risk or modeling transport to groundwater of PCDD/Fs in soil.
Department of Applied Environmental Sciences (ITM), Stockholm University, 10691 Stockholm, Sweden; Norwegian Geotechnical Institute (NGI), P.O. Box 3930 Ullevaal, N-0806 Oslo, Norway. Electronic address: gerard.cornelissen@itm.su.se.
Gerard
G
Cornelissen
Department of Applied Environmental Sciences (ITM), Stockholm University, 10691 Stockholm, Sweden.
Ian T
IT
Cousins
Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden.
Karin
K
Wiberg
Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden.
Mats
M
Tysklind
Geological Survey of Sweden (SGU), P.O. Box 16247, SE-10324 Stockholm, Sweden.
Henning
H
Holmström
Department of Applied Environmental Sciences (ITM), Stockholm University, 10691 Stockholm, Sweden.
Dag
D
Broman
D000327:Adsorption; D001572:Benzofurans / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins / Q000031:analogs & derivatives* / Q000737:chemistry; D012987:Soil / Q000032:analysis*
D001572:Benzofurans; D000072338:Dibenzofurans, Polychlorinated; D000072317:Polychlorinated Dibenzodioxins; D012987:Soil; D002244:Carbon