# Extraction and characterization methods for microplastics from estuarine and coastal samplings – example of the 2019 Tara expedition

Lata Soccalingame, Maialen Palazot, Mikaël Kedzierski, Stéphane Bruzaud

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Lata Soccalingame, Maialen Palazot, Mikaël Kedzierski, Stéphane Bruzaud. Extraction and characterization methods for microplastics from estuarine and coastal samplings – example of the 2019 Tara expedition. Monitoring of Mediterranean coastal areas: problems and measurement techniques, Jun 2022, Livorno, Italy. **hal-05208637**

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https://ubs.hal.science/hal-05208637v1

Submitted on 13 Aug 2025

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# EXTRACTION AND CHARACTERIZATION METHODS FOR MICROPLASTICS FROM ESTUARINE

IRDL
Institut de Recherche Dupuy de Lôme
UMR CNRS 6027

## AND COASTAL SAMPLINGS - EXAMPLE OF THE 2019 TARA EXPEDITION

L. Socscalingame, M. Notheaux, M. Palazot, M. Kedzierski, S. Bruzaud

Université Bretagne Sud, IRDL, UMR CNRS 6027, 56100 Lorient, France

Université
Bretagne Sud
ubs:

## CONTEXT OF THE STUDY

The TARA Microplastics 2019 [1] mission aims to investigate plastic pollution in European rivers across different scientific fields of study:

Among the 19 partner laboratories, the IRDL objectives are:

* Quantify the microplastic pollution,

* Characterize the microplastics (size, chemical identification).

<figure><img src="image_2.png" /></figure>

Plastic
chemistry

<figure><img src="image_3.png" /></figure>

Physical
oceanography

<figure><img src="image_4.png" /></figure>

Marine
biology

<figure><img src="image_5.png" /></figure>

© Maëva Bardy / Fondation Tara Océan

<figure><img src="image_6.png" /></figure>

EXAMPLE OF TIBER:
5 SAMPLING SPOTS
ALONG THE RIVER

<figure><img src="image_7.png" /></figure>

Fondation
tara océan
explore and share

© Illustration studio.v2 / Fondation Tara Océan

9 European rivers

- Seine

- Loire

- Garonne

- Thames

- Elbe

- Rhine

- Ebro

- Rhone

- Tiber

## MATERIALS AND METHODS

### FIELD SAMPLINGS (IN RIVERS AND AT SEA)

<figure><img src="image_8.png" /></figure>

© François Aurat / Fondation Tara Océan

45 surface samplings in 9 rivers with
a 300-µm mesh size manta trawl
hundreds of m³ of filtered water

<figure><img src="image_9.png" /></figure>

<figure><img src="image_10.png" /></figure>

### ORGANIC MATTER DIGESTION

High amount of organic matter (algae, leaves, branches, etc.)
=  
need for a combination of two digestion protocols

KOH followed by H₂O₂

Digestion in two successive steps:
KOH (10%, 40°C, 48h) then H₂O₂ (30%, room T°,
overnight) (~72h in total)

Fenton's reagent

H₂O₂ (30%) with an iron catalyst [2]: FeSO₄·7H₂O
T°C <40°C (in ice bath) (1 to 4h)
Iron oxides rinsed with HCl (1 M)

<figure><img src="image_11.png" /></figure>

### DENSITY SEPARATION

<figure><img src="image_12.png" /></figure>

50 mL Falcons

<figure><img src="image_13.png" /></figure>

Filtration of the supernatant
to extract all MP

Nal solution (sodium iodide)
Density = 1,8 g.cm⁻³

<figure><img src="image_14.png" /></figure>

Inorganic matter removal
(clay, sand, etc.).

Microplastics > 500 µm
disposed in Petri dishes

<figure><img src="image_15.png" /></figure>

<figure><img src="image_16.png" /></figure>

### IMAGE ANALYSIS WITH FIJI SOFTWARE

<figure><img src="image_17.png" /></figure>

<figure><img src="image_18.png" /></figure>

analysis program
written in Java
available on request

### Counting and size measurement

50 to 1500 particles per manta in the range of 500µm to 5mm

<figure><img src="image_19.png" /></figure>

### CHEMICAL IDENTIFICATION BY INFRARED SPECTROSCOPY (ATR-FTIR)

<figure><img src="image_20.png" /></figure>

### Random draw of microplastics

(to limit the number of particles to analyse)

<figure><img src="image_21.png" /></figure>

### POSEIDON

<figure><img src="image_22.png" /></figure>

Open-source, developed
with R i386 3.1.2

### Automated analysis with
Poseidon software

(Plastic pOllutionS Extraction,
DetectiOn and aNalysis)

## PRELIMINARY RESULTS

<figure><img src="image_23.png" /></figure>

Feret length of particles from Tiber S4
(downstream of Roma)

1500 particles were
detected, 92 were
randomly drawn from the
processed image

Statistical approach allows
to pick microplastics in the
whole size range

<figure><img src="image_24.png" /></figure>

Particle circularity as a function of
the feret length for Tiber S4

Most of the particles are in
the range of 0,8 – 1,6 mm
in feret length

Greater feret length
= more elongated shape

<figure><img src="image_25.png" /></figure>

Proportions of polymer types for
microplastics from Tiber S4

### Top 3 plastic materials :

1) Polyethylene (PE)

2) Polypropylene (PP)

3) Polystyrene (PS)

## CONCLUSION

<figure><img src="image_26.png" /></figure>

SAMPLING, MICROPLASTIC EXTRACTION AND CHARACTERIZATION
METHODS ARE SIMILAR FOR ALL SAMPLING SITES

AUTOMATION AND STATISTICAL APPROACH
(RANDOM DRAW) ARE NECESSARY

<figure><img src="image_27.png" /></figure>

## PERSPECTIVES

<figure><img src="image_28.png" /></figure>

HYDRODYNAMIC CONDITIONS OF THE DIFFERENT SAMPLING SITES ?

INFLUENCE OF THE SEASONS ?

TEMPORAL MONITORING IS NECESSARY

<footnote>[1] Tara's Blue Book: Tracing the Origins of Plastic Pollution (2020), 69 p.</footnote>

<footnote>[2] Hurley, R. R., Lusher, A. L., Olsen, M., & Nizzetto, L. (2018). Validation of a Method for Extracting Microplastics from Complex, Organic-Rich, Environmental Matrices. Environ. Sci. Technol., 52(13), 7409–7417.</footnote>