The sorption of persistent organic pollutants in microplastics from the coastal environment

Microplastic (MP) pellets were sampled from six sandy beaches around Taiwan in order to investigate the concentrations and compositions of POPs, including: PCDD/Fs, PBDD/Fs, PBDEs, PCBs, PBBs, and their congeners. The concentrations of PCDD/Fs on the surface (C_s) of MP pellets from the six sampling sites were from 1.9 to 14.6 pg∙g^-1, while the overall concentrations within MPs (C_t) were from 95.0 to 1110.6 pg∙g^-1. As PCDD/Fs were adsorbed into the inner part of MPs, a ratio of the total concentrations to surficial concentration of MPs (C_t/C_s) was as high as 355.2 times. The C_t/C_s of other POPs were also significant, such as PBDEs being found up to 8068 times, which could be attributed to artificial addition during manufacturing processes as flame-retardant substances. Primary compositions of PCDD/Fs, PBDD/Fs, and PBDEs on the MPs in our POP congener analysis were all found containing species with higher number of chlorine or bromine, which were adsorbed on the MP surface more easily due to their relative higher K_OW.