A new small device made of glass for separating microplastics from marine and freshwater sediments.

Ryota Nakajima,Tomohiko Fukushima,Tomo Kitahashi,Katsunori Fujikura,Masashi Tsuchiya,Dhugal J Lindsay

doi:10.7717/peerj.7915

Abstract

Separating microplastics from marine and freshwater sediments is challenging, but necessary to determine their distribution, mass, and ecological impacts in benthic environments. Density separation is commonly used to extract microplastics from sediments by using heavy salt solutions, such as zinc chloride and sodium iodide. However, current devices/apparatus used for density separation, including glass beakers, funnels, upside-down funnel-shaped separators with a shut-off valve, etc., possess various shortcomings in terms of recovery rate, time consumption, and/or usability. In evaluating existing microplastic extraction methods using density separation, we identified the need for a device that allows rapid, simple, and efficient extraction of microplastics from a range of sediment types. We have developed a small glass separator, without a valve, taking a hint from an Utermöhl chamber. This new device is easy to clean and portable, yet enables rapid separation of microplastics from sediments. With this simple device, we recovered 94–98% of <1,000 µm microplastics (polyethylene, polypropylene, polyvinyl chloride, polyethylene terephthalate, and polystyrene). Overall, the device is efficient for various sizes, polymer types, and sediment types. Also, microplastics collected with this glass-made device remain chemically uncontaminated, and can, therefore, be used for further analysis of adsorbing contaminants and additives on/to microplastics.

Highlights

IntroductionMicroplastics, small pieces of plastic ranging from five mm in size down to microscopic, are ubiquitously distributed particulate contaminants that have been to-date detected in various environmental samples, including freshwater lakes and rivers (Eriksen et al, 2013; Free et al, 2014; Gasperi et al, 2014; Biginagwa et al, 2016), seas and oceans, including the deep-sea and the polar regions (Lusher et al, 2014; Shim & Thomposon, 2015; Bergmann et al, 2017; Matsuguma et al, 2017; Wang et al, 2019)
A new small device made of glass for separating microplastics from marine and freshwater sediments
We have not yet reached a consensus about the amounts of microplastics accumulating in oceanic and freshwater sediments, how these microplastics were transported into the sediments, and what their impact is on benthic animals (Farrell & Nelson, 2013; Ugolini et al, 2013; Law & Thompson, 2014; Green et al, 2016)

Summary

Introduction

Microplastics, small pieces of plastic ranging from five mm in size down to microscopic, are ubiquitously distributed particulate contaminants that have been to-date detected in various environmental samples, including freshwater lakes and rivers (Eriksen et al, 2013; Free et al, 2014; Gasperi et al, 2014; Biginagwa et al, 2016), seas and oceans, including the deep-sea and the polar regions (Lusher et al, 2014; Shim & Thomposon, 2015; Bergmann et al, 2017; Matsuguma et al, 2017; Wang et al, 2019) Once they end up in aquatic environments, microplastics eventually accumulate in/on the surface water, shores/beaches, and in the sediments of benthic environments (Hidalgo-Ruz & Thiel, 2013; Van Cauwenberghe et al, 2013; Law & Thompson, 2014; Van Sebille et al, 2015). Developing an efficient method for detecting microplastics from sediments is an important issue for further understanding the distribution, mass, and ecological impacts of microplastics in both marine and freshwater environments

Methods

Results

Conclusion