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Size, shape and density characterization of environmental grinded microplastic

Dipartimento di Scienze Fisiche, della Terra e dell’Ambiente

Corso di Laurea Magistrale in:

ECOTOSSICOLOGIA E SOSTENIBILITÀ AMBIENTALE

Nome: Angelo Mecca

Relatore: Cristina Panti

Correlatore: Maria Cristina Fossi

Introduction

Marine litter : "any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment" UNEP 2009

Introduction

Plastic, synthetic polymer used for several manufacturings, represents the most common litter and is global widespread.

Production

Leaderboard

1

Polyethylene (PE)

2

Polypropylene (PP)

Leaderboard

3

Polystyrene (PS)

4

Polyvinyl chloride (PVC)

5

Polyethylene terephthalate (PET)

Behavior and input

Microplastic

Particle with diameter < 5 mm

Primary vs Secondary

78% of major pollutants (US EPA 2013) are associated with marine plastic litter (Rochman et al. 2013a)

POPs

PBTs

PBDEs BPA

Phthalates

Factors

Environment:

  • Class and concentration of chemicals themselves in the surrounding environment

Chemicals

Particles:

  • surface area
  • size
  • hydrophobicity
  • crystallinity
  • high surface/volume ratio
  • polymer
  • diffusivity

Pathway, behaviour and fate in the environment

(distribution and accumulation rate)

  • size
  • shape
  • polymer

Sinking behavior

Settling velocity

  • hydrodynamics factors
  • weathering
  • biofouling
  • bathymetry
  • geomorphology
  • salinity
  • temperature
  • presence/absence of rivers

Environmental pathway and behavior

Shape characterization:

  • Corey shape factor (CSF)

Size characterization:

  • Major dimension
  • Equivalent spherical diameter (ESD)

Polymer characterization

Aim

Image analyzer software has been proposed to use pictures for counting and evaluation of the dimensions of the particles.

Cryo-milled environmental microplastic

Aim

Materials and methods

Range 300 µm - 5 mm

- FTIR = polymer type identification

- Camera Nikon, Adobe Photoshop and ImageJ = counting and dimensions evaluation

Volume and ESD evaluation

Visual and manual sorting at WUR laboratories

Materials and methods

Sampling:

Singapore (Changi beach)

The Netherlands (Hoek van Holland)

CSF evaluation

a = longest dimension

b = intermediate dimension

c = shortest dimension

- Cryo-milling

- Wet sieving (5 mm - 180 µm)

- 48 hours oven

- Dry sieving

L = length

W = width

H = height

L:W = W:H

Wageningen University & Research (WUR) -

Aquatic Ecology and Water Quality Management

Results

Counting: 2159

Results

Major dimension distribution

Kernel density estimation (KDE)

Major dimension

Items abundance

Height

h1 => min = 54.645 µm max = 7,238.742 µm, mean = 1,255.354 µm

h2 = 166 µm

h3 = 225.161 µm

h4 = 224.269 µm

Volume

Volumes and ESD

ESD

Kernel density estimation(KED)

CSF

Kernel density estimation (KDE)

CSF

Polymer type

Polymer type Number of items Abundance (%)

Poly (propylene) 361 62.13

Poly (ethylene) 191 32.87

Poly (vinyl chloride) 8 1.38

Polymer type

LDPE (0.910 – 0.940 g/cm3)

PE =

HDPE (> 0.940 g/cm3)

PP = 0.946 g/cm3

Density

Kp

- surrounding environment

- compounds

- characteristics of the particles

- different for each polymer

Equilibrium partition coefficient

Conclusions

  • According this study, the evaluation methods for height (3) and (4) were revealed to be the most credible and truthful methods. As consequence, volume and ESD based on two aforementioned heights are considered plausible. According CSF results, the particles tend to present a balanced ration among the three orthogonal dimensions. As expected, PP and PE are the two most abundant polymer types.

  • The use of pictures and image analyzer software for automatic counting of particles and measuring of their dimensions was revealed to be a reliable and plausible approach.

  • Regarding the usage of environmental grinded microplastic, the results were trustworthy, realistic and comparable with both lab-based studies and environmental observations

Conclusion

Skyscraper by Studiokca

"Skyscraper rises from this canal in Utrecht, to remind us all of the enormous problem of plastic waste in our oceans.

This gigantic sculpture is more than just a representation of a whale. The piece is made from 5 tons of plastic waste pulled out of our oceans, to serve as powerful reminder of the 150 000 000 tons of plastic waste still swimming out there"

Thank you

Wageningen University & Research -

Aquatic Ecology and Water Quality Management

Dr. Koelmans A.A., Dr. Mohamed Nor, N. H and Dr. Kooi M.

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