Guidelines for Harmonizing Ocean Surface Microplastic Monitoring Methods

Abstract

This document presents the version (1.2) of “Guidelines for Harmonizing Ocean Surface Microplastic Monitoring Methods” (herein after referred to as the Guidelines). Its primary goal is to propose ways of harmonizing methodologies for monitoring microplastic densities at the ocean surface to deliver comparable results. Specifically, the Guidelines indicate the rationale for various sample collection methods, sample handling and processing, analytical procedures, reporting requirements, and other matters necessary or desirable for harmonization. Preparation of the Guidelines was based on the output of the international workshop held in 2015 as a follow-up to the “G7 Action Plan to Combat Marine Litter” agreed on in the G7 Elmau Summit 2015, and a follow-up meeting held in 2019 based on “G20 Implementation Framework for Actions on marine plastic litter” endorsed in the G20 Osaka Summit 2019. It was indicated that Japan would lead the harmonization efforts for microplastic monitoring methods in the workshop and the followup meeting held in 2019. The Guidelines were developed on the basis of opinions and recommendations compiled at international meetings of microplastic monitoring experts and the results of dedicated in situ and laboratory experiments newly conducted toward harmonization, as well as existing findings collected and summarized from published microplastic monitoring survey reports, guidelines, and manuals. Estimating the abundance and/or distribution of microplastics in water bodies has become internationally important. At present, several sets of guidelines and other documents are being developed by some international organizations including GESAMP. The Guidelines presented here were designed to supplement and complement such documents, and to propose detailed methodologies focusing on net sampling and analysis. The outcomes of which are to contribute validated and comparable data which can be used to produce horizontal distribution maps (two dimensional maps; 2-D maps) of microplastics at the global ocean surface. Many studies are expected to be carried out to monitor microplastics at the ocean surface. The application of the harmonized methods proposed in the Guidelines will support these efforts to generate comparable results. Thus, enabling researchers to analyze, consolidate and integrate the results on a wider scale. Through such an application, we strongly believe that our understanding of the abundance of microplastics in the ocean will improve. Shared and integrated monitoring results will promote higher level analysis of microplastic issues and application to policy development. These outcome and progress will be share at various international meetings including G20. The first revision of the Guidelines was made one year after their first publication and this second revision was made two years after the first revision. The Guidelines will be updated and improved as necessary.