Issue 11, 2022

Microplastics contributed much less than organic matter to the burial of polycyclic aromatic hydrocarbons by sediments in the past decades: a case study from an urban lake

Abstract

The role of microplastics in burying hydrophobic organic compounds remains largely unknown. Sediment cores collected from the center of a typical urban lake (Lake Qianhu) in China were chosen to explore the contribution of microplastics to the burial of polycyclic aromatic hydrocarbons (PAHs) by sediments, and to elucidate how this contribution changed with microplastic composition and the hydrophobicity of PAHs on a decade scale. Our results showed that the concentration of individual PAHs adsorbed by microplastics varied from detection limit (LOD) to 7.2 mg g−1 MP, which was much higher than the LOD to 31.0 μg g−1 TOC buried by total organic carbon. However, the amount of individual PAHs adsorbed by microplastics only contributed to 0–34.2% of that in sediments. Changes in the composition of microplastics, including the increased proportion of polyethylene and polypropylene : polyethylene polymer in sediments, resulted in the average microplastic sediment burial ratios (MSBRs) of most PAHs increasing by 0.13% to 2.7% in the period from 1997 to 2018 compared with those in the period from 1975 to 1996. The average MSBRs varied with the hydrophobicity of PAHs, which increased with log Kow value if it varied from 3.45 to 5.20, but decreased with log Kow if it was in the range of 5.30 to 6.50. Our study provides novel knowledge on the contribution of microplastics to the burial of PAHs by sediments.

Graphical abstract: Microplastics contributed much less than organic matter to the burial of polycyclic aromatic hydrocarbons by sediments in the past decades: a case study from an urban lake

Supplementary files

Article information

Article type
Paper
Submitted
22 Jul 2022
Accepted
26 Sep 2022
First published
27 Sep 2022

Environ. Sci.: Processes Impacts, 2022,24, 2100-2107

Microplastics contributed much less than organic matter to the burial of polycyclic aromatic hydrocarbons by sediments in the past decades: a case study from an urban lake

L. Zhang and Y. Tao, Environ. Sci.: Processes Impacts, 2022, 24, 2100 DOI: 10.1039/D2EM00309K

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