Organic compounds associated with microplastic pollutants in New Jersey, U.S.A. surface waters

Extensive manufacturing and ubiquitous use in every sector of today’s society has resulted in plastics being detected in all terrestrial and aquatic environments examined to date. However, the pervasiveness of small, potentially invisible, microplastics, their associated chemical additives, and organic compounds that absorb to plastic substrates are the topics of recent investigations. These micro- to nano- size plastic particles that are deliberately manufactured or were fragmented from larger plastic products are now ending up in food webs and worldwide environmental systems. Using a pyrolysis GC-MS method, plastic polymer composition was determined in samples obtained from freshwaters in urban New Jersey. Three polymers dominated the samples: polyethylene (43%), polypropylene (33%), and polystyrene (13%). The dominant polymers differed in each river. To identify Persistent Organic Pollutants sorbed to microplastic particles, headspace solid phase micro extraction coupled with gas chromatography/ion trap mass spectrometry was employed. In the majority of upriver sampling locations, Tentatively Identified Compounds were associated with both the microplastic and the water column fractions in roughly equal proportions. However, in the tidal portion of the Passaic River and in samples from Newark and Raritan Bays, the majority of organic compounds were associated with the microplastic fraction only. Based on a search of chemical databases, the possible source/use of 180 of the 223 compounds identified, whose total mass was 1 ng or more, was determined. Forty one percent of the identified compounds were natural substances, thirty five percent were identified as laboratory/research chemicals and seven percent were pharmaceutical or biomedical compounds. Twelve identified compounds are used for industrial purposes, including a plasticizer and an insecticide. Six compounds are used as cosmetic additives. The findings of this study illustrate the diversity of organic compounds associated with the presence of microplastics in aquatic media.