A methodology for the sampling and identification of microplastics in bird nests

Plastic pollution has significantly impacted terrestrial ecosystems and using bird nests to monitor microplastics in the environment is economical, uses green reagents, is relatively easy to sample, and is non-invasive. The plastics can generally be fragmented in the nests, giving rise to mesoplastics and later to microplastics. Microplastics (MPs) in nests can cause adverse effects on the chicks that ingest them by mistaking them for their food. In addition, chemical compounds such as pesticides, hydrocarbons, heavy metals, and flame retardants, among many others, can be adhered to the MPs. Therefore, applying green methodologies to determine microplastics in bird nests is of importance since it is an environmentally friendly manual technique due to the fact that no reagents or chemical substances are used during the nest-breaking procedures and MPs separation, and allows to perform other analyses. The methodology was applied to nests of Great-tailed grackle (Quiscalus mexicanus) from an urban area. The results of MPs in the nests of this study presented an average of 250.3 ± 221.3 items/nest. The mean (± SE) of MPs per kilogram of a nest was 2,535.3 ± 2,175.9 items/kg. The most abundant MPs were the synthetic fibers composed of polyethylene and polypropylene. The proposed step-by-step methodology does not use reagents, so it is considered a sustainable analytical method (Green chemistry).