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Developing a systematic method for extraction of microplastics in soils

Developing a systematic method for extraction of microplastics in soils
Developing a systematic method for extraction of microplastics in soils
Microplastics are an environmental issue of global concern. Although they have been found in a range of environments worldwide, their contamination in the terrestrial environment is poorly understood. The lack of standardised methods for their detection and quantification is a major obstacle for determining the risk they pose to soil environments. Here we present a systematic comparison of microplastic extraction methods from soils, taking into account the characteristics of the soil medium to determine the best methods for quantification. The efficiency of organic matter removal using hydrogen peroxide, potassium hydroxide and Fenton's reagent was measured. Soils with a range of particle size distribution and organic matter content were spiked with a variety of microplastic types. Density separation methods using sodium chloride, zinc chloride and canola oil were tested. Recovery efficiencies were calculated and the impact of the reagents on the microplastics was quantified using Attenuated Total Reflectance (ATR) Fourier Transform-Infrared (FTIR) spectroscopy. The optimal organic removal method was found to be hydrogen peroxide. The recovery efficiency of microplastics was variable across polymer types. Overall, canola oil was shown to be the optimal method for density separation, however, efficiency was dependent on the amount of organic matter in the soil. This outcome highlights the importance of including matrix-specific calibration in future studies considering a wide range of microplastic types, to avoid underestimation of microplastic contamination. We show here that methods for extracting microplastics from soils can be simple, cost-effective and widely applicable, which will enable the advancement of microplastic research in terrestrial environments.
mircoplastics, soils, extraction, density separation, Analytical method
1759-9660
1695-1705
Radford, Freya
f43f5d73-b100-424a-9021-8f17f7715e35
Zapata Restrepo, Lina
2276abeb-952d-4475-9620-bd0885291f64
Horton, Alice A.
3b4dfc8c-2a5d-48c9-8c63-8a113a2a1bfe
Hudson, Malcolm
1ae18506-6f2a-48af-8c72-83ab28679f55
Shaw, Peter
935dfebf-9fb6-483c-86da-a21dba8c1989
Williams, Ian
c9d674ac-ee69-4937-ab43-17e716266e22
Radford, Freya
f43f5d73-b100-424a-9021-8f17f7715e35
Zapata Restrepo, Lina
2276abeb-952d-4475-9620-bd0885291f64
Horton, Alice A.
3b4dfc8c-2a5d-48c9-8c63-8a113a2a1bfe
Hudson, Malcolm
1ae18506-6f2a-48af-8c72-83ab28679f55
Shaw, Peter
935dfebf-9fb6-483c-86da-a21dba8c1989
Williams, Ian
c9d674ac-ee69-4937-ab43-17e716266e22

Radford, Freya, Zapata Restrepo, Lina, Horton, Alice A., Hudson, Malcolm, Shaw, Peter and Williams, Ian (2021) Developing a systematic method for extraction of microplastics in soils. Analytical Methods, 13 (14), 1695-1705. (doi:10.1039/D0AY02086A).

Record type: Article

Abstract

Microplastics are an environmental issue of global concern. Although they have been found in a range of environments worldwide, their contamination in the terrestrial environment is poorly understood. The lack of standardised methods for their detection and quantification is a major obstacle for determining the risk they pose to soil environments. Here we present a systematic comparison of microplastic extraction methods from soils, taking into account the characteristics of the soil medium to determine the best methods for quantification. The efficiency of organic matter removal using hydrogen peroxide, potassium hydroxide and Fenton's reagent was measured. Soils with a range of particle size distribution and organic matter content were spiked with a variety of microplastic types. Density separation methods using sodium chloride, zinc chloride and canola oil were tested. Recovery efficiencies were calculated and the impact of the reagents on the microplastics was quantified using Attenuated Total Reflectance (ATR) Fourier Transform-Infrared (FTIR) spectroscopy. The optimal organic removal method was found to be hydrogen peroxide. The recovery efficiency of microplastics was variable across polymer types. Overall, canola oil was shown to be the optimal method for density separation, however, efficiency was dependent on the amount of organic matter in the soil. This outcome highlights the importance of including matrix-specific calibration in future studies considering a wide range of microplastic types, to avoid underestimation of microplastic contamination. We show here that methods for extracting microplastics from soils can be simple, cost-effective and widely applicable, which will enable the advancement of microplastic research in terrestrial environments.

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Accepted/In Press date: 8 March 2021
e-pub ahead of print date: 22 March 2021
Keywords: mircoplastics, soils, extraction, density separation, Analytical method

Identifiers

Local EPrints ID: 449987
URI: http://eprints.soton.ac.uk/id/eprint/449987
ISSN: 1759-9660
PURE UUID: 0d77f7da-4719-4402-a82e-231cb2e217dc
ORCID for Freya Radford: ORCID iD orcid.org/0000-0002-9742-279X
ORCID for Peter Shaw: ORCID iD orcid.org/0000-0003-0925-5010
ORCID for Ian Williams: ORCID iD orcid.org/0000-0002-0121-1219

Catalogue record

Date deposited: 01 Jul 2021 16:34
Last modified: 02 Jul 2021 01:56

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Contributors

Author: Freya Radford ORCID iD
Author: Lina Zapata Restrepo
Author: Alice A. Horton
Author: Malcolm Hudson
Author: Peter Shaw ORCID iD
Author: Ian Williams ORCID iD

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