Globally, little is known about the dispersal of microplastics (MP) and anthropogenic particles (AP) via atmospheric deposition (AD) into water bodies. Correlating AD to the large number of MP in estuaries is challenging but an important first step toward reducing this form of pollution. A previously published model of the surface waters of the Indian River Lagoon (IRL, east central coast of Florida, USA) estimated it contained 1.4 trillion microplastics. To determine if AD could produce this much plastic deposition, we deployed passive AD collectors throughout a 145 km² area at three site types with assistance from citizen scientists. We predicted that the rate of deposition of MP and AP would be greatest in residential areas, intermediate within a national park, and lowest on intertidal oyster reefs. Moreover, we predicted Florida’s wet season and individual rain events would increase deposition based on the published literature. Over 14 months, deposition averaged 1224 MP/m²/d; extrapolated, this yields 1.1 trillion MP for the lagoon-wide total deposition estimate (95% CI: 0.86–1.39 trillion MP). This value suggests that AD may represent an important pathway for MP to enter this estuary. More MP were deposited during rain events and in the wet season, with no differences among sites. Overall, our results provide important data for understanding AD of MP and AP in estuaries.

Feral and domestic felines are continuously exposed to meso- (polymer length: 5–25 mm) and microplastics (polymer length < 5 mm) from environmental or household contaminants. Ingestion and inhalation are the primary pathways for internalization of plastic, non-plastic anthropogenic (e.g., rayon, AP), and natural cellulose particles. However, contamination information is limited for companion animals. This study focused on reproductive tissue of felines by obtaining samples from spay (ovary + uterus) and neuter (testes) procedures. The tissue was chemically digested and then analyzed via microscopy and Fourier-Transform Infrared Spectroscopy (FTIR) to detect and identify contamination. Overall, 71% of 100 individuals contained particles (meso- and microplastics, non-plastic anthropogenic particles, cellulose), of which 97.3% were fibers. Foreign particles were present in the uterus and ovaries of 100% of domestic females, while only 36% of feral males had particles in their testes. Overall, 25% of the FTIR-confirmed particles were plastic, 54% were AP, and 21% were cellulose. The most common plastic found was polyethylene terephthalate (PET), a common polymer used in packaging food and beverages, including manufactured cat food and bottled water. This study provides a baseline for understanding plastic and AP concentrations in the reproductive tissues of both feral and domestic felines.