Transport of polycyclic aromatic hydrocarbons and polychlorinated biphenyls in a landfill: A novel equilibrium passive sampler to determine free and total dissolved concentrations in leachate water

Equilibrium passive sampling devices consisting of 17-μm thick polyoxymethylene (POM) were in situ deployed as a novel technique for landfill groundwater leachate water sampling of freely dissolved polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs). POM was deployed in two groundwater leachate wells (flow around 100 m y−1) and an effluent leachate tank. The dissipation of >90% of spiked performance reference compounds and comparison between 60 d and 140 d of equilibration confirmed that POM–water equilibrium was reached for all PAHs and most PCBs within 60 d. Comparison of total and freely dissolved concentrations yielded dissolved organic carbon–water distribution ratios that were on average 0.4 log-unit below amorphous organic carbon–water distribution ratios and in accordance with literature values. Particle-bound fractions ranged from 50% (small PAHs) to 99.9% (large PCBs), and were >95% for most compounds. It was concluded that POM-17 equilibrium passive samplers provide a facile method to measure freely dissolved concentrations of PAH and PCB in groundwater leachate, which will yield valuable information on its ecotoxicological risk for aquatic and benthic organisms.