The Accumulation of Microplastics in Different Estuaries

Abstract

Microplastics are primarily produced by the fragmentation of larger plastic materials via physical, chemical, or biological means. They are carried by wind and water to various marine environments, such as estuaries, and deposited into sediments. Estuaries are microplastic sinks and can provide information about dominant plastic types and microplastic retention in marine environments. Various studies have produced inconsistent results when comparing microplastics and their sediments. The amount of microplastics accumulated in the sediments is thought to depend on grain size. Samples were collected from two locations along the western coast of North America (Craigs Bay and Netarts Bay) to determine if different depositional environments affect the accumulation and retention of microplastics. Approximately 12.5g of each sample was sifted through various sieves (4000, 2000, 1000, 500, 250, 125, and 63µm, respectively) to determine their grain size distributions and dominant grain size. Microplastics were extracted from an unsorted portion of each sample using a density floatation and enzyme digestions. They were also classified by shape: fragment, fiber, film, and pellets. The overall quantity in each sample was combined with each samples’ grain size distribution to determine if the different depositional environments affect the accumulation and retention of microplastics. The work is part of a new and emerging research area within sedimentology that focuses on the correlation between sediments and microplastics.

Department: Physical Sciences

Faculty Mentors: Dr. Matthew Ross and Dr. Hilary Corlett