TY - JOUR

T1 - Microplastic analysis in soils

T2 - A comparative assessment

AU - Peneva, S.

AU - Le, Q.N.P.

AU - Munhoz, D.R.

AU - Wrigley, O.

AU - Wille, F.

AU - Doose, H.

AU - Halsall, C.

AU - Harkes, P.

AU - Sander, M.

AU - Braun, M.

AU - Amelung, W.

N1 - Export Date: 18 December 2024 CODEN: EESAD Correspondence Address: Braun, M.; Institute of Crop Science and Resource Conservation (INRES), Nussallee 13, Germany; email: melanie.braun@uni-bonn.de Funding details: Horizon 2020 Framework Programme, H2020, 55334 Funding details: Horizon 2020 Framework Programme, H2020 Funding details: European Commission, EC, 955334 Funding details: European Commission, EC Funding text 1: This work was supported by the European Union's Horizon 2020, ITN SOPLAS, with grant agreement No. 955334 to the five first authors. The authors thank Elisabeth Shaw and Alexandre Benedetto (Lancaster University) for their help with the fluorescence microscope measurement; Markus Rhode, Ulrich Meinke and Sven Simons (Wessling GmbH) for the expertise provided for the measurements with Raman Microscope and Pyrolysis\u2013Gas Chromatography\u2013Mass Spectroscopy; Prof Violette Geissen for supporting and supervising the work done at Wageningen University and Research. Funding text 2: This work was supported by the European Union\u2019s Horizon 2020, ITN SOPLAS, with grant agreement No. 55334 to the five first authors. The authors thank Elisabeth Shaw and Alexandre Benedetto (Lancaster University) for their help with the fluorescence microscope measurement; Markus Rhode, Ulrich Meinke and Sven Simons (Wessling GmbH) for the expertise provided for the measurements with Raman Microscope and Pyrolysis\u2013Gas Chromatography\u2013Mass Spectroscopy; Prof Violette Geissen for supporting and supervising the work done at Wageningen University and Research.

PY - 2025/1/1

Y1 - 2025/1/1

N2 - Microplastic (MiP) contamination poses environmental risks, but harmonizing data from different quantification methods and sample matrices remains challenging. We compared analytical protocols for MiP quantification in soil, consisting of Digital, Fluorescence, Fourier-transform infrared (FTIR), and Raman Microscopy as well as quantitative Pyrolysis-Gas Chromatography-Mass Spectroscopy (Py-GC-MS) and 1-proton nuclear magnetic resonance (1H NMR) spectroscopy as detection techniques. Each technique was coupled with a specific extraction procedure and evaluated for three soils with different textures and organic carbon contents, amended with eight types of large MiPs (0.5–1 mm) – high- and low-density polyethylene (HDPE and LDPE), polypropylene (PP), polystyrene (PS), polyamide (PA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and a biodegradable mulch film product composed of polybutylene adipate-co-terephthalate/ polylactic acid (PBAT/ PLA). In addition, we included two types of small MiPs (20–250 µm) composed of either LDPE or PBAT/ PLA in the tests. The results showed that protocols for Digital, Fluorescence, and ATR-FTIR microscopy recovered 74–98 % of the large MiPs, with fluorescence yielding the highest recoveries. Raman spectroscopy was most sensitive to soil organic matter residues, requiring more sophisticated sample pretreatment. Fluorescence staining with subsequent Fluorescence microscopy detection effectively recovered most small-sized LDPE-MiP but missed 56–93 % of small PBAT/ PLA particles. For the latter, reliable quantification was achieved only using Soxhlet extraction combined with 1H NMR spectroscopic quantification. Pyrolysis-GC-MS showed intermediate results, displaying low sensitivity to plastic type and lower recoveries as soil clay content increased. We conclude that different methods have different sensitivities for different MiP materials in different soils, i.e. comparisons of MiP loads and threshold settings for MiP loads across methodologies require careful consideration. Yet, our data indicate that adding stained large MiP as an internal standard could enhance extraction control, while Soxhlet-extraction with subsequent 1H NMR analysis is most powerful for controlling future thresholds of small MiP from biodegradable materials.

AB - Microplastic (MiP) contamination poses environmental risks, but harmonizing data from different quantification methods and sample matrices remains challenging. We compared analytical protocols for MiP quantification in soil, consisting of Digital, Fluorescence, Fourier-transform infrared (FTIR), and Raman Microscopy as well as quantitative Pyrolysis-Gas Chromatography-Mass Spectroscopy (Py-GC-MS) and 1-proton nuclear magnetic resonance (1H NMR) spectroscopy as detection techniques. Each technique was coupled with a specific extraction procedure and evaluated for three soils with different textures and organic carbon contents, amended with eight types of large MiPs (0.5–1 mm) – high- and low-density polyethylene (HDPE and LDPE), polypropylene (PP), polystyrene (PS), polyamide (PA), polyethylene terephthalate (PET), polyvinyl chloride (PVC), and a biodegradable mulch film product composed of polybutylene adipate-co-terephthalate/ polylactic acid (PBAT/ PLA). In addition, we included two types of small MiPs (20–250 µm) composed of either LDPE or PBAT/ PLA in the tests. The results showed that protocols for Digital, Fluorescence, and ATR-FTIR microscopy recovered 74–98 % of the large MiPs, with fluorescence yielding the highest recoveries. Raman spectroscopy was most sensitive to soil organic matter residues, requiring more sophisticated sample pretreatment. Fluorescence staining with subsequent Fluorescence microscopy detection effectively recovered most small-sized LDPE-MiP but missed 56–93 % of small PBAT/ PLA particles. For the latter, reliable quantification was achieved only using Soxhlet extraction combined with 1H NMR spectroscopic quantification. Pyrolysis-GC-MS showed intermediate results, displaying low sensitivity to plastic type and lower recoveries as soil clay content increased. We conclude that different methods have different sensitivities for different MiP materials in different soils, i.e. comparisons of MiP loads and threshold settings for MiP loads across methodologies require careful consideration. Yet, our data indicate that adding stained large MiP as an internal standard could enhance extraction control, while Soxhlet-extraction with subsequent 1H NMR analysis is most powerful for controlling future thresholds of small MiP from biodegradable materials.

KW - Conventional synthetic and biodegradable polymers

KW - Soil pollution

KW - Spectroscopy

KW - microplastic

KW - organic carbon

KW - polyamide

KW - polyethylene terephthalate

KW - polylactic acid

KW - polypropylene

KW - polystyrene

KW - polyvinylchloride

KW - soil organic matter

KW - Article

KW - environmental risk

KW - fluorescence

KW - fluorescence microscopy

KW - Fourier transform infrared spectroscopy

KW - human

KW - mass spectrometry

KW - microscopy

KW - nuclear magnetic resonance spectroscopy

KW - pyrolysis gas chromatography mass spectroscopy

KW - Raman microscopy

KW - soil

KW - Soxhlet extraction

U2 - 10.1016/j.ecoenv.2024.117428

DO - 10.1016/j.ecoenv.2024.117428

M3 - Journal article

VL - 289

JO - Ecotoxicology and Environmental Safety

JF - Ecotoxicology and Environmental Safety

SN - 0147-6513

M1 - 117428

ER -