2017 perspective (and opinion) on experimental framework for microplastic monitoring Martin Hassellöv Department of Marine Sciences, University of Gothenburg Martin.hassellov@marine.gu.se
Content • Current end-user need of environmental surveillance of microplastic • Perspective on gap in knowledge or aggreement on definitions and classifications • Harmonization issues of sampling • Harmonization issues of the analytical procedures • Examples from our research activities • Perspectives on pressing research needs
Monitoring • link to sources • baseline and trends, link to measures • Where to measure?
Water compartment - very dynamic • Standing stock=f(input+ import+macrofragmentation- nanofragmentation-sedimentation-beaching-uptake,…) • Variability= f(precipitation, sun, temp, wind, seasonal activities,…) • Sediments more stable standing stock, but too stable…? (bioturbation, trawling, dredging,…)
Perspective on gap in aggreement on definitions and classifications • Nota Bene Litter -not just plastics & microlitter not just microplastics • NB Plastics is not just variations of the same thing – Large variation of chemical, physical and biological properties – Very different environmental conseqeunces (fate, half-life, effects) • Large focus on size spectra – Agreement on size is important but not all • NB Buoyancy for example, is a function of size, shape and composition (and also weathering and fate processes)
Size spectra • Arbitrary limits put on a size continuum • Upper limit – 5mm or 1mm? • Lower limit – Poorly defined – Operational • JPI Oceans goal: 1µm • Nanoplastics – New concept – 1nm-1µm / 1-100nm – Studies on nanoplastics largely lacking
Plastic Size Continuum – what shall we measure? Primary particles inputs Proxy for? Proxy for? NanoPlastics MicroPlastics MesoPlastics MacroPlastics Fragmentation? Comprehensive, advanced analysis required simpler analysis required High surface area, high particle numbers low numbers, large mass, particle volume Cellular uptake, biomagnification, biochemical ingestion physical effects entanglement Diffusing, Colloidal behavior, bioavailable? slowly settling rapid floatation or rapid sinking
Sampling considerations – water compartment • No single methods can sample from macro to nano, not even the entire microplastic size ranges – Different volumes (sampling effort) needed for statistical power within each size fraction – Clogging effects – Sea surface microlayer vs pelagic – … • So choices need to be made, and several methods combined
Manta-trawl Floating litter >300µm • Conventional wide, 1-2 knop • High-Speed, narrow, up to 8 knots • Self-planing or suspended by a ships crane • Accurate sampling of sea surface. Less accurate volume sampler •
On-line filtration from sampler bottle, Ruttner sampler, subsurface • Ruttner sampler, clean sampling • Easy and low cost • Simple to filter directly from bottle
Sampling intercomparison manta trawl vs in situ pump (w. Örebro U.) • 6 replicates, repeated same day, same station, simultaneously • Same but different - sampling principles: – Same mesh size 300µm – Volume: ~120m3 trawl (estimate), ~20m3 pump (measured) – Translates to different measurement uncertainties due to counting statistics – Sea surface microlayer: trawl yes; pump no ? 0,45 n=8 , σ 35% 0,40 0,35 Trawl Plastic particles per m3 0,30 Pumpfiltration n=34 , σ 17% 0,25 n=26 , σ 20% n=4, σ 50% 0,20 0,15 n=3 n=15 , σ 26% n=2 , σ 71% 0,10 n=11 , σ 30% 0,05 0,00 n=0
Different analytical workflow approaches • Visual categorization – Limit in size (> ~100-300µm)* *TGD Marine litter 2013 • Visual – handpicking – FTIR/RAMAN – Accurate ID – Time consuming – Size limit of handpicking ~50µm • Automated mapping FTIR – Elaborate pretreatment – Advanced instrumentation FPA-FTIR – Powerful ID – Size limit ~15µm • Automated LM-SEM-RAMAN – Multi-dimensional analysis, Powerful ID – Advanced instrumentation – Size limit ~0.5µm – Automation still under development
Vibration spectroscopy supported microscopy • Infrared absorption spectroscopy (Fourier Transform IR, FTIR) – Reflectance – Transmission – Attenuated total reflection (ATR) – Simpler, less expensive, .. • Raman scattering spectroscopy – Exitation with laser – Inelastic scattering (loss of energy) – Raman emission (similar to luminescence),
New case study commissioned by Swedish Marine and Water Management The Uddevalla Byfjorden gradient study Samples from sediment, surface, deep water, trawl, microplastic filters, nanoplastics
Case study: Oslofjorden
Visual classification, #/m3 T11 T10 T9 T8 T7 T6 T5 T4 T3 T2 T1 0,00 5,00 10,00 15,00 20,00 Black filament Blue filament Red filament Green filament Transparent filament White filament Other filament Black NS filament Blue NS filament Red NS filament Transparent NS filament Black fragment Blue fragment Red fragment Green fragment Transparent fragment White fragment Other fragment White foam Other foam Black foil
FTIR identification; >300µm
Automated mapping FTIR Chemical Image Vis-Image Particles Microplastics Acknowl: Gunnar Gerdts, AWI, Germany
Correlative microscopy • Light Microscope => SEM-EDS – Correlative sample holder – Shuttle ´n Find calibrated transfer • SEM-EDS => LM • LM => RAMAN • Raman inside SEM, (RISE) – Confocal RAMAN mounted parallel to electron beam in SEM
Correlativ microscopy in our lab Optical microscope Scanning Raman Electron microscopes: microscope Insitu and confocal
Automatiserad analys i SEM-EDS • Backscattering detection (heavy element contrast) • Set brightness-contrast threshold • Setup entire filter in fields of view • Identify particles • Perform Elemental analysis on each particle • Measure morphology • Classify composition and size classes
Results – antifouling paint particles from ship lane in Baltic Sea Styr mikroskopet till varje partikel som har hög Avbilda i SEM kopparhalt Flytta till LM Avbilda i LM
Red copper rich particles – ship lane Bornholm
Hazard prioritizations… • Hazard ranking based on effect studies or chemical composition? • In time we may be more informed to prioritize – until then we should measure as wide as possible • Some bad and ugly could possibly warrant high prio already now
pID
The needle in the haystack… • To find a handfull tin-rich (TBT?) microparticles in 2L water among millions of natural particles would not be possible without the selective screening methodology and correlative microscopy • Now we are extending the technique to also include RAMAN-µ-spektroskopi
Reference particles*from JPI-O BASEMAN BASEMAN particles Correlative microscopy system PP PVC PMMA PA Optical LDPE microscope PMMA PC Scanning Electron microscope Raman PP microscopes: Insitu and confocal PVC PS PA HDPE * Ref particles have been spiked to sediments, biota tissue and plankton for harmonization ring triel studies
Acknowledgements Prof. Martin Hassellöv Therese Karlsson Dr. Karin Mattsson Dr. Andreas Gondikas
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