Environ. Chem. 2015, 12, 527-538 ©CSIRO 2015 ©CSIRO 2014 doi:10.1071/EN15012_AC Supplementary material Questions of size and numbers in environmental research on microplastics: methodological and conceptual aspects Montserrat FilellaA,B AInstitute F.-A. Forel, University of Geneva, Route de Suisse 10, CH-1290 Versoix, Switzerland. Email: [email protected] BSCHEMA, Rue Principale 92, L-6990 Rameldange, Luxembourg. Page 1 of 34 Environ. Chem. 2015 ©CSIRO 2015 doi:10.1071/EN15012_AC Table S1. Microplastics in aquatic systems. location, type of sample, sampling procedure, initial separation and sample treatment methods, and identity verification in published studies Studies are listed in chronological order, starting with the most recent Reference Location Type of system Type of sample Number of Sampling or Sample treatmentB Verification sampling initial size points; separation number of samplesA Sediments [1] Norderney Island, Tidal mudflats Drift lines (2) and 3; 36 Sieving 1 mm >1 mm: none 32 random particles Germany dune valley (1), mesh analysed by TD-Pyr- <1 mm: flotation (saturated NaCl, d upper 3 cm layer GC/MS, 47% confirmed = 1.2 g cm–3 + NaI, d = 1.8 g cm–3); as described in Nuelle et al.[2] [3] Singapore Mangroves Top 3–4 cm at low 7; ? No sieving Flotation (concentrated saline ‘a representative group tide mentioned solution, d = 1.18 g dm–3), addition of microplastics’ Tween-80, filtration 0.1 cm and 1.6 identified by ATR-FTIR’ μm [4] Atlantic Ocean, Deep-sea sediments ~1000 m deep 12 No sieving 8 samples: flotation (concentrated FTIR Mediterranean Sea, (some 12 years old) 8: upper 1 cm; 4: mentioned NaCl), filtration (size not given)[5] Indian Ocean 2, 5 cm 4 samples: flotation (Ludox-TM 40), centrifugation, filtration 32 μm[6] [7] Portugal coast Beaches Top 2 cm at high 10; not Sieving ~3-mm As described in Martins and μ-FTIR in some resin tide level given (3–5 metal mesh Sobral[8] pellets replicates for each location) Page 2 of 34 Environ. Chem. 2015 ©CSIRO 2015 doi:10.1071/EN15012_AC Reference Location Type of system Type of sample Number of Sampling or Sample treatmentB Verification sampling initial size points; separation number of samplesA [9] –3 Lake Garda, Italy Lake beaches Top 5 cm 2; 6 No sieving Flotation (1.6–1.7 kg dm ZnCl2), Raman mentioned filtration 0.3 μm; as described in microspectroscopy Imhof et al.[10] [11] Mumbai, India Beaches High-tide mark, 4; 240? Sieving 1 mm Flotation (140 g dm–3 NaCl) No top 2 cm [12] Near Nakdong Beaches Strandline, upper 5 6; 90? Tyler sieves 5, 1 No estuary, South Korea cm mm [13] Belgian Continental Beaches Upper 5 cm, at the 4; 8 Sieving 1 mm Elutriation, sieving 35 μm, flotation No Shelf low- and high- (1.6 g cm–3 NaI), filtration 5 μm, as water mark described in Claessens et al.[14] [15] Atlantic Ocean Deep-sea sediments Only top 1 cm of 4; 11 Wet sieving Flotation (1.6 g cm–3 NaI), filtration Raman (1176–4844 m deep) the cores 1 mm, then 35- 0.8 μm microspectroscopy considered μm mesh Mediterranean Sea Nile deep sea fan [16] Venice Lagoon, Italy Shallow water 0–5 cm sediments 10; 20 No sieving Flotation (120 g dm–3 NaCl), sieving Surface chemical sediments (<1m (box-corer) mentioned 32 μm, filtration 0.7 μm; as mapping of filters by μ- depth) described in Thompson et al.[5] FTIR; observation by ESEM-EDS [17] Lake Geneva, Lake beaches 2, 5-mm sieves Flotation (water) No Switzerland [18] East Frisian islands: Beaches and tidal flats Upper 1 cm 11 (from No sieving OM H2O2 digestion, flotation (1.5 g No Spiekeroog, figure); ? mentioned cm–3 ZnCl2), filtration 1.2 μm Kachelotplate Page 3 of 34 Environ. Chem. 2015 ©CSIRO 2015 doi:10.1071/EN15012_AC Reference Location Type of system Type of sample Number of Sampling or Sample treatmentB Verification sampling initial size points; separation number of samplesA [19] Ocean Beach, San Beaches Upper 1 cm of 1; 16? Sieving 2 mm No details No Diego, California, US sand [20] Hawaiian Beaches 25 cm sediment 2; 30 No sieving Flotation (1.2 g cm–3 NaCl); brass 248 plastic fragments Archipelago (Kamilo, cores mentioned US sieves (4, 2, 1, 0.5, 0.25 mm) analysed by FTIR Waikapuna beaches) [21] Belgian coast Harbours Subtidal sediments 3; 11 No sieving Flotation (concentrated saline ‘Particles of each type’ mentioned solution), sieving 38-μm mesh; as analysed by FTIR Beaches High, subtidal, 3 [5] described in Thompson et al. middle Coastal shelf Subtidal sediments 6 [8] Portugal Beaches Last high tide 5 A: No sieving A: Flotation (140 g dm–3 NaCl), Some ‘selected’ items mark, top 2 cm filtration 1 μm analysed by FTIR sand B: In situ sieving B: ‘plastic set apart from the 2.5 × 3.5-mm remained debris’ How? metal mesh [22] Lake Huron, Canada Lake beaches – 7 No sieving Air-drying, sonication 45 particles analysed by mentioned FTIR [23] Tamar estuary, UK Strandlines Underlying 3 cm 6; 30 No sieving Flotation (saturated solution of FTIR of sediment mentioned NaCl); as described in Thompson et al.[5] [24] Boa Viagem, Recife, Beach Strandline, upper 2 1; 9 Sieving 1 and Washing in filtered seawater No Brazil cm of sand 0.5 mm wire cloths Page 4 of 34 Environ. Chem. 2015 ©CSIRO 2015 doi:10.1071/EN15012_AC Reference Location Type of system Type of sample Number of Sampling or Sample treatmentB Verification sampling initial size points; separation number of samplesA [25] Fernando de Beaches Strandline, upper 2 11; 15 Sieving 1 mm – No Noronha, Equatorial cm of sand Western Atlantic [26] Singapore Beaches 0.5 m away from 7; 26 No sieving Flotation (1.2 kg dm–3 saline FTIR analysis for all the ocean tideline; mentioned solution), filtration 1.6 μm; as suspected particles some points top 1 described in Thompson et al.[5] cm; some at 10– 11-cm depth [27] Hawaiian archipelago Beach High-tide line and 9; 22 Only particles 1– – Dry sort: none No bern, top 5.5 cm 15 mm retained – Wet sort: cleaning with water sand (nested sieves: 4.75, 2.8, 1 mm) [5] Around Plymouth, Beach (sandy Strandline 6; 30 No sieving Flotation (1.2 kg dm–3 NaCl), FTIR UK intertidal) mentioned filtration Estuarine sediment (intertidal) Subtidal sediment Water [28] Bay of Calvi, Coastal surface First 0.2 m of sea 1; 38 Floating wp2 net Plastic particles separated from No Corsica, Italy seawater surface (200-μm mesh) organic tissue by gravity in graduated cylinders Page 5 of 34 Environ. Chem. 2015 ©CSIRO 2015 doi:10.1071/EN15012_AC Reference Location Type of system Type of sample Number of Sampling or Sample treatmentB Verification sampling initial size points; separation number of samplesA [29] Worldwide open Surface seawater 141 sites; Neuston net Mixed with 0.2-mm-filtered Raman applied to a oceans 3070 (200-μm mesh) seawater random subset of particles (n = 67) [30] NE Pacific Ocean Subsurface seawater 4.5-m depth 2 cruises; Pumped, Cu sieves (250, 125, 62.5 μm), each ‘Plastics identified 34 (saltwater intake fraction OM acid digestion (conc according morphological Coastal British system of the HCl), filtration 47 μm characteristics and Columbia, Canada vessel), filtration physical response 5 mm features (e.g., response to physical stress)’ [31] Lake Hovsgol, Lake water 9 transects Manta trawl Tyler sieves (0.355–0.999, 1.00– No Mongolia (333-μm mesh) 4.749, >4.75 mm), each fraction OM H2O2 digestion, flotation (1.62 g cm–3 salt water) [32] Portuguese coastal Coastal surface Upper 20 cm of 4; 152 Neuston net (280 Filtration mentioned but no pore size μ-FTIR, number of waters (Aveiro, seawater water column μm), plankton given, just diameter of filter! analysed samples not Lisboa, Costa except with recorder (335 clear Vicentina, Algarve) plankton recorder μm) (25 m deep) [33] Seto Inland, Japan Coastal surface 4; 15 Neuston net (350 – μ-FTIR, number of seawater μm) analysed samples not clear [34] Goiana estuary, Estuarine waters Surface and 1; 216 Plankton net ‘Floating plastics’ sieved 45-μm No Brazil bottom hauls (300 μm) mesh Page 6 of 34 Environ. Chem. 2015 ©CSIRO 2015 doi:10.1071/EN15012_AC Reference Location Type of system Type of sample Number of Sampling or Sample treatmentB Verification sampling initial size points; separation number of samplesA [35] Highly urbanized River water 2; 8 Neuston net (333 Stacked sieves (2 mm, 350 μm), OM No river, Chicago, US μm) H2O2 digestion, flotation (NaCl) [36] Tamar estuary, Estuarine waters Surface water 4?; 36? Manta net (300- Set of sieves (3 mm, 1 mm, 270 μm) FTIR on 50% of the England μm mesh) pieces from each size group [37] Coastal areas close to Coastal surface SML (150–400 10; 20? SML, bulk SML: filtration 0.75 μm All SML: FTIR Nakdong River, seawater μm) waters water, hand net Bulk water: filtration 1, 0.75 μm Other: only ‘selected’ South Korea (50-μm mesh): filtration, manta Hand and trawl: sieving 2 mm: >2 trawl (330-μm mm counted, <2 mm: H2O2 digested, mesh) filtered 0.75 μm [38] Yangtze estuary, Estuarine and surface estuary: 1 m deep 1; 7 Estuary: OM H2O2 digestion, flotation No [18] China seawater pumped, sieving (saturated ZnCl2 solution), 32 μm filtration 1.2 μm East China Sea 3; 15 Sea: neuston net (333 μm) [39] Jade System, Coastal seawater 20-cm depth 14; 2 100 mL PE In one case: 40-μm sieve, OM H2O2 No Southern North Sea replicates bottles filling, digestion filtration 1.2 μm [40] Laurentian Great Lake surface water 3 lakes; 21 Manta trawl Flotation (salt water), Tyler sieves All particles <1 mm Lakes (Erie, Huron, (333-μm net) (0.355–0.999, 1.00–4.749, >4.75 analysed by SEM-EDS Superior) mm) Page 7 of 34 Environ.