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. 2022 Jan 7;194(2):65.
doi: 10.1007/s10661-021-09664-0.

Selection of a density separation solution to study microplastics in tropical riverine sediment

Thi Thuy Duong  1   2 , Phuong Thu Le  3 , Thi Nhu Huong Nguyen  4 , Thi Quynh Hoang  4 , Ha My Ngo  3 , Thi Oanh Doan  5 , Thi Phuong Quynh Le  6 , Huyen Thuong Bui  3 , Manh Ha Bui  7 , Van Tuyen Trinh  4 , Thuy Lien Nguyen  8 , Nhu Da Le  6 , Thanh Mai Vu  9 , Thi Kim Chi Tran  9 , Tu Cuong Ho  4 , Ngoc Nam Phuong  10 , Emilie Strady  11
Affiliations

Selection of a density separation solution to study microplastics in tropical riverine sediment

Thi Thuy Duong et al. Environ Monit Assess. .

Abstract

Microplastics (MPs) are small (< 5 mm) plastic particles that are widely found in marine, freshwater, terrestrial and atmospheric environments. Due to their prevalence and persistence, MPs are considered an emerging contaminant of environmental concern. The separation and quantitation of MPs from freshwater sediments is a challenging and critical issue. It is necessary to identify the fate and sources of MPs in the environment, minimise their release and adverse effects. Compared to marine sediments, standardised methods for extracting and estimating the amount of MPs in freshwater sediments are relatively limited. The present study focuses on MP recovery efficiency of four commonly used salt solutions (NaCl, NaI, CaCl2 and ZnCl2) for isolating MPs during the density separation step from freshwater sediment. Known combinations of artificial MP particles (PS, PE, PVC, PET, PP and HDPE) were spiked into standard river sediment. Extraction using NaI, ZnCl2 and NaCl solutions resulted in higher recovery rates from 37 to 97% compared to the CaCl2 solution (28-83%) and varied between polymer types. Low-density MPs (PE, HDPE, PP and PS) were more effectively recovered (> 87%) than the denser polymers (PET and PVC: 37 to 88.8%) using NaCl, NaI and ZnCl2 solutions. However, the effective flotation of ZnCl2 and NaI solutions is relatively expensive and unsafe to the environment, especially in the context of developing countries. Therefore, considering the efficiency, cost and environmental criteria, NaCl solution was selected. The protocol was then tested by extracting MPs from nine riverine sediment samples from the Red River Delta. Sediments collected from urban rivers were highly polluted by MPs (26,000 MPs items·kg-1 DW) compared to sediments located downstream. Using a NaCl solution was found to be effective in this case study and might also be used in long-term and large-scale MP monitoring programmes in Vietnam.

Keywords: Density separation; Microplastics; Riverine sediment; Urban rivers; Vietnam.

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References

    1. Abdurahman, A., Cui, K., Wu, J., Li, S., Gao, R., Dai, J., Liang, W., & Zeng, F. (2020). Adsorption of dissolved organic matter (DOM) on polystyrene microplastics in aquatic environments: Kinetic, isotherm and site energy distribution analysis. Ecotoxicology and environmental safety, 198, p.110658. https://doi.org/10.1016/j.ecoenv.2020.110658
    1. Abidli, S., Toumi, H., Lahbib, Y., & Trigui El Menif, N. (2017). The first evaluation of microplastics in sediments from the complex lagoon-channel of Bizerte (northern Tunisia). Water, Air, and Soil Pollution, 228(7). https://doi.org/10.1007/s11270-017-3439-9
    1. Alam, F. C., Sembiring, E., Muntalif, B. S., & Suendo, V. (2019). Microplastic distribution in surface water and sediment river around slum and industrial area (case study: Ciwalengke River, Majalaya district, Indonesia). Chemosphere, 224, 637–645. https://doi.org/10.1016/j.chemosphere.2019.02.188 - DOI
    1. Anderson, J. C., Park, B. J., & Palace, V. P. (2016). Microplastics in aquatic environments: Implications for Canadian ecosystems. Environmental Pollution, 218, 269–280. https://doi.org/10.1016/j.envpol.2016.06.074 - DOI
    1. Andrady, A. L. (2011). Microplastics in the marine environment. Marine Pollution Bulletin, 62(8), 1596–1605. https://doi.org/10.1016/j.marpolbul.2011.05.030 - DOI

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