Passive sampling of DDT, DDE and DDD in sediments: accounting for degradation processes with reaction–diffusion modeling

• DOI: 10.1039/c7em00501f
• Publication Date: 2017-12-11T19:33:45Z
• Authors: A. Patricia Tcaciuc; Raffaella Borrelli; Luciano M. Zaninetta; Philip M. Gschwend
• Keywords: Degradation; Reactivity

Passive sampling is becoming a widely used tool for assessing freely dissolved concentrations of hydrophobic organic contaminants in environmental media. For certain media and target analytes, the time to reach equilibrium exceeds deployment time, such cases, loss performance reference compounds (PRCs), loaded sampler before deployment, one common ways assess fractional equilibration analytes. The key assumption behind use PRCs that their release solely diffusion driven. But this work, we show PRC transformations sediment can have measurable impact on releases even allow estimation compound's transformation rate environment interest. We found both field lab incubations, 13C 2,4'-DDT from polyethylene (PE) passive deployed at sediment-water interface was accelerated compared other (13C-labeled PCBs, 13C-labeled DDE DDD). DDT also accompanied by accumulation PE its degradation product, 2,4'-DDD. Using 1D reaction-diffusion model, deduced situ rates measured loss. increased with depth into bed (0.14 d-1 0-10 cm 1.4 30-40 cm) although they could not be independently validated, these favorably literature values. This work shows users should cautious when choosing PRCs, as processes affect some PRC's sampler. More importantly, opens up opportunity novel applications samplers, particularly regard investigating rates, pathways, products legacy emerging contaminants. However, further needed confirm model fitting are true reflection sediments.