Volatilization of polychlorinated biphenyls from sediment during drying at ambient conditions

Air drying sediment from a Federal Superfund Site for 24 hours at ambient conditions (T=20°C; RH=25%) resulted in PCB volatilization losses of 14–23%, with 80–90% of the total loss occurring within the first eight hours. A sample dried for 24 hours lost 21.3% of PCBs via volatilization and an additional 7.5% during a second 24 hour drying period after rewetting. PCB loss was positively correlated with water loss (R2 > .99). Sediment samples ( 0.25 grams) suspended in 100 milliliters of double deionized water that was allowed to evaporate over a 7 day period lost 74–76% of their initial PCB concentration. Lower orthochlorinated congeners volatilized preferentially. These data indicate PCB loss through volatilization during drying at ambient conditions is more significant than previously recognized, particularly for sediments that have undergone extensive anaerobic microbial PCB dechlorination.