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A low-tech, mass-based community-scientist-oriented method for routine microplastics monitoring in coastal systems
Citation:
Langknecht, T., D. El Khatib, J. Farnan, R. Burgess, AND K. Ho. A low-tech, mass-based community-scientist-oriented method for routine microplastics monitoring in coastal systems. SETAC North America 44th Annual Meeting, Louisville, KY, November 12 - 16, 2023.
Impact/Purpose:
Microplastics, which are plastic pieces smaller than 5 mm, are abundant in aquatic ecosystems, particularly in marine sediments. Marine sediments are home to many organisms that play important roles in their ecosystem. Quantifying microplastics is increasingly important to understanding their impact on these ecosystems. However, methods for quantifying microplastics in sediments are very expensive and take considerable time and specialized laboratory instrumentation, making it difficult to conduct long-term, routine monitoring. Routine monitoring is important to better understand how microplastics can affect the environment and to provide data to lawmakers for future policy decisions. This study aimed to develop a new method for measuring microplastics in sediment that uses inexpensive materials, less time than traditional methods, and is accessible to scientists of any level. We conducted a series of tests to determine the best strategies and materials. The final method, called Oxidation of Microplastics in Sediment, involves a density separation with sodium bromide and two organic digestions with muriatic acid and bleach. The samples are then weighed to determine the loss of sediment and the remaining mass should consist of only microplastics. We are now testing the effectiveness of the method with environmental samples from Massachusetts. The intended audience of this research includes state, local, and federal agencies interested in conducting microplastic research, as well as academic and private research institutions.
Description:
Sediments are a major sink for microplastics (MP) and while methods for extracting and identifying MP in sediment have improved in recent years, these methods continue to be time and cost intensive and scientifically rigorous. The cost of specialized identification instrumentation can be prohibitive for state agencies, universities, nonprofit organizations, and participatory science groups (i.e., citizen or community science). Further, the analysis time can restrict sampling sizes and replication, geographical area covered, and number of times each site is visited (i.e., single sampling vs. multi-year). Consequently, routine monitoring is resource intensive, thus limiting the availability of baseline and long-term datasets for MP, which are essential for policy development and understanding threats to humans and the environment. The objective of this study was to create and validate a method for detecting MP in sediment that is cost-effective, suitable for scientists of any level, and less time intensive. A series of experiments were conducted on MP spiked sediment samples to optimize the method, including testing various digestion solutions, lengths of digestion and density separation, and combustion, among others. The finalized method, called Oxidation of Microplastics in Sediment (OMS), consists of a 24-hour density separation with a high density (1.5 g/mL) sodium bromide solution to remove dense particulates followed by two 24-hour digestions with muriatic acid (5%) and bleach (7%) to eliminate inorganic carbon and non-polymers. The samples are then filtered over a pre-weighed polycarbonate filter and re-weighed to determine the remaining sample mass (i.e., operationally defined MP). OMS is being validated on 14 marine sediment samples collected off the coast of Massachusetts, USA. This work provides a fast, low-tech, mass-based method for detecting MP in aquatic sediments. With this method, we attempt to open opportunities for routine monitoring of MP across larger areas and allow for rapid detection of changes in MP concentration in coastal systems.
URLs/Downloads:
https://www.setac.org/discover-events/global-meetings/setac-north-america-44th-annual-meeting/general-info/important-dates.html