Adsorption of perfluoroalkyl substances on microplastics under environmental conditions

Plastic debris has become an environmental problem during recent years. Among the plastic debris, microplastics (<5 mm; MPLs) imply an extra problem due to their capacity to enter into the fauna through ingestion. In this work, we study the capacity of three MPLs, that include high-density polyethylene (HDPE), polystyrene (PS) and polystyrene carboxylate (PS-COOH), to sorb 18 perfluoroalkyl substances (PFASs; including carboxylic acids, sulphonates and one sulphonamide) from the surrounding waters (freshwater and seawater). Conclusions drawn from the results are that perfluoro sulphonates and sulphonamides have more tendency to be sorbed onto MPLs. In addition, PS and PS-COOH have more affinity for PFASs than HDPE. Finally, the increment of conductivity and pH of the water decreases the exposure time that is necessary to reach equilibrium. However, the presence of salts decreases the tendency of PFASs to be sorbed onto plastic surfaces. These results highlight the problem associated with the presence of MPLs in inland and marine waters since toxic compounds can be sorbed onto surrounding plastics that could be ingested by aquatic fauna.

This work has been supported by INTEGRA-COAST project (CGL2014-56530-C4-1-R). It was also partly supported by the Generalitat de Catalunya (Consolidated Research Groups “2014 SGR 418-Water and Soil Quality Unit”, “2014 SGR 291- Catalan Institute for Water Research 2014 SGR 291”). GS acknowledges PhD scholarship (BES-2015-072281) and ML acknowledges her Juan de la Cierva – Incorporación research fellowship (JdC-2014-21736) both from the Spanish Ministry of Economy, Industry and Competitiveness.

Peer reviewed