PCB volatile loss and the moisture content of sediment during drying

PCB volatile loss shows a positive correlation with sediment moisture content during drying. Small amounts (0.25 g) of St. Lawrence River sediment were allowed to dry for periods of 24 hours under ambient conditions and lost up to 4μg of PCBs by volatilization. Submerged sediment lost the greatest amount of PCBs (26.9%), while dry sediment lost 0.3% of total PCB concentration. Four, entirely orthochlorinated congeners (2; 2/2; 2/6; 26/2), produced by anaeorbic degradation, account for 54–76% of the PCB total volatilized in each experiment with added moisture. With the complete evaporation of water or depletion of lower orthochlorinated congeners, the rate of volatile loss slows substantially. These results have numerous implications for the analysis, potential exposure pathways, and global fate and transport processes of persistent organic pollutants.