Transfer of Microplastics in Terrestrial and Aquatic Food Webs: The Impact of E-Waste Debris and Ecological Traits

Factors affecting the trophic transfer of microplastics (MPs) in aquatic and terrestrial ecosystems remain to be clarified. Here, we determined the abundances of MPs in multiple terrestrial and aquatic species, including insects, snails, crustaceans, fishes, snakes, birds, and voles, from an abandoned e-waste recycling site. Approximately 80% of MPs were within the size range 20-50 μm. In wildlife, the MP abundances per individual and per body weight were found to be positively and negatively correlated with body weight, respectively. Herein, terrestrial vertebrates, primarily birds, exhibited more complex compositions of polymer types than other organisms owing to the wide foraging areas and diverse food sources. However, according to the MPs modeled and the observed results in bird food chains, MPs do not appear to be preferentially retained in the bird gastrointestinal tract. The species-specific polymer types identified indicate the influences of habitat on MP pollution in organisms, which is further supported by significant correlations between the abundance of MPs and δ13C in the terrestrial food web (p < 0.05). In the analyzed bird species, the low MP abundance detected in birds compared with the amount of food ingested indicates that MPs constitute a negligible factor in the bioaccumulation of chemical pollutants.