TY - JOUR
T1 - Sample size requirements for riverbank macrolitter characterization
AU - de Lange, Sjoukje I.
AU - Mellink, Yvette
AU - Vriend, Paul
AU - Tasseron, Paolo F.
AU - Begemann, Finn
AU - Hauk, Rahel
AU - Aalderink, Heleen
AU - Hamers, Eric
AU - Jansson, Peter
AU - Joosse, Nonna
AU - Löhr, Ansje J.
AU - Lotcheris, Romi
AU - Schreyers, Louise
AU - Vos, Vivien
AU - van Emmerik, Tim H.M.
N1 - Funding Information:
This research was partly funded by the Netherlands Ministry of Infrastructure and Water Management, Directorate-General for Public Works and Water Management (Rijkswaterstaat). The work of TvE is supported by the Veni Research Program, The River Plastic Monitoring Project with project number 18211, which is (partly) funded by the Dutch Research Council (NWO). YM received funding from The Ocean Cleanup.
Publisher Copyright:
Copyright © 2023 de Lange, Mellink, Vriend, Tasseron, Begemann, Hauk, Aalderink, Hamers, Jansson, Joosse, Löhr, Lotcheris, Schreyers, Vos and van Emmerik.
PY - 2023/1/19
Y1 - 2023/1/19
N2 - Anthropogenic litter is omnipresent in terrestrial and freshwater systems, and can have major economic and ecological impacts. Monitoring and modeling of anthropogenic litter comes with large uncertainties due to the wide variety of litter characteristics, including size, mass, and item type. It is unclear as to what the effect of sample set size is on the reliability and representativeness of litter item statistics. Reliable item statistics are needed to (1) improve monitoring strategies, (2) parameterize litter in transport models, and (3) convert litter counts to mass for stock and flux calculations. In this paper, we quantify sample set size requirement for riverbank litter characterization, using a database of more than 14,000 macrolitter items (>0.5 cm), sampled for 1 year at eight riverbank locations along the Dutch Rhine, IJssel, and Meuse rivers. We use this database to perform a Monte Carlo based bootstrap analysis on the item statistics, to determine the relation between sample size and variability in the mean and median values. Based on this, we present sample set size requirements, corresponding to selected uncertainty and confidence levels. Optima between sampling effort and information gain is suggested (depending on the acceptable uncertainty level), which is a function of litter type heterogeneity. We found that the heterogeneity of the characteristics of litter items varies between different litter categories, and demonstrate that the minimum required sample set size depends on the heterogeneity of the litter category. This implies that more items of heterogeneous litter categories need to be sampled than of heterogeneous item categories to reach the same uncertainty level in item statistics. For example, to describe the mean mass the heterogeneous category soft fragments (>2.5 cm) with 90% confidence, 990 items were needed, while only 39 items were needed for the uniform category metal bottle caps. Finally, we use the heterogeneity within litter categories to assess the sample size requirements for each river system. All data collected for this study are freely available, and may form the basis of an open access global database which can be used by scientists, practitioners, and policymakers to improve future monitoring strategies and modeling efforts.
AB - Anthropogenic litter is omnipresent in terrestrial and freshwater systems, and can have major economic and ecological impacts. Monitoring and modeling of anthropogenic litter comes with large uncertainties due to the wide variety of litter characteristics, including size, mass, and item type. It is unclear as to what the effect of sample set size is on the reliability and representativeness of litter item statistics. Reliable item statistics are needed to (1) improve monitoring strategies, (2) parameterize litter in transport models, and (3) convert litter counts to mass for stock and flux calculations. In this paper, we quantify sample set size requirement for riverbank litter characterization, using a database of more than 14,000 macrolitter items (>0.5 cm), sampled for 1 year at eight riverbank locations along the Dutch Rhine, IJssel, and Meuse rivers. We use this database to perform a Monte Carlo based bootstrap analysis on the item statistics, to determine the relation between sample size and variability in the mean and median values. Based on this, we present sample set size requirements, corresponding to selected uncertainty and confidence levels. Optima between sampling effort and information gain is suggested (depending on the acceptable uncertainty level), which is a function of litter type heterogeneity. We found that the heterogeneity of the characteristics of litter items varies between different litter categories, and demonstrate that the minimum required sample set size depends on the heterogeneity of the litter category. This implies that more items of heterogeneous litter categories need to be sampled than of heterogeneous item categories to reach the same uncertainty level in item statistics. For example, to describe the mean mass the heterogeneous category soft fragments (>2.5 cm) with 90% confidence, 990 items were needed, while only 39 items were needed for the uniform category metal bottle caps. Finally, we use the heterogeneity within litter categories to assess the sample size requirements for each river system. All data collected for this study are freely available, and may form the basis of an open access global database which can be used by scientists, practitioners, and policymakers to improve future monitoring strategies and modeling efforts.
KW - anthropogenic litter
KW - database
KW - heterogeneity
KW - macroplastic
KW - Meuse
KW - Rhine
KW - sample set size requirements
KW - sampling
UR - http://www.scopus.com/inward/record.url?scp=85147314686&partnerID=8YFLogxK
U2 - 10.3389/frwa.2022.1085285
DO - 10.3389/frwa.2022.1085285
M3 - Article
AN - SCOPUS:85147314686
SN - 2624-9375
VL - 4
JO - Frontiers in Water
JF - Frontiers in Water
M1 - 1085285
ER -