title: Desorption kinetics of hydrophobic organic contaminants from marine plastic pellets.
abstract: This study investigated the desorption behavior of polychlorinated biphenyls (PCBs) from marine plastic pellets. Long-term desorption experiments were conducted using field-collected polyethylene (PE) pellets. The results indicate that the desorption kinetics highly depends on the PE-water partition coefficients of PCB congeners. After 128 d of the experiment, the smallest congener considered (CB 8) had desorbed nearly completely (98%), whereas major fractions (90-99%) of highly chlorinated congeners remained in the pellets. An intraparticle diffusion model mostly failed to reproduce the desorption kinetics, whereas an aqueous boundary layer (ABL) diffusion model well approximated the data. The desorption half-lives are estimated to 14 d to 210 years for CB 8 to CB 209 in an actively stirred solution (ABL thickness: 30 μm). Addition of methanol to water enhanced the desorption to a large extent. A need for further work to explore roles of organic matter in facilitating solute transfer is suggested.
authors.affiliation: Department of Analytical Environmental Chemistry, UFZ - Helmholtz Centre for Environmental Research, Permoserstrasse 15, D-04318 Leipzig, Germany. Electronic address: satoshi.endo@ufz.de.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Endo
authors.forename: Masaki
authors.initials: M
authors.lastname: Yuyama
authors.forename: Hideshige
authors.initials: H
authors.lastname: Takada
mesh_terms: D000327:Adsorption; D057927:Hydrophobic and Hydrophilic Interactions; D007700:Kinetics; D008956:Models, Chemical; D010969:Plastics / Q000737:chemistry*; D011078:Polychlorinated Biphenyls / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D010969:Plastics; D014874:Water Pollutants, Chemical; D011078:Polychlorinated Biphenyls
keywords: Aqueous boundary layer; Marine debris; Polychlorinated biphenyl (PCB); Polyethylene; Resin pellet