Microplastics in coral reef sediments underestimated? They may hide in biominerals

Chih-Feng Chen; Yun-Ru Ju; Chiu-Wen Chen; Frank Paolo Jay B Albarico; Yee Cheng Lim; Chongtai Ke; Yu-Rong Cheng; Cheng-Di Dong

doi:10.1016/j.scitotenv.2023.165708

Microplastics in coral reef sediments underestimated? They may hide in biominerals

Sci Total Environ. 2023 Nov 15:899:165708. doi: 10.1016/j.scitotenv.2023.165708. Epub 2023 Jul 21.

Authors

Chih-Feng Chen¹, Yun-Ru Ju², Chiu-Wen Chen¹, Frank Paolo Jay B Albarico³, Yee Cheng Lim¹, Chongtai Ke¹, Yu-Rong Cheng⁴, Cheng-Di Dong⁵

Affiliations

¹ Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City 81157, Taiwan.
² Department of Safety, Health and Environmental Engineering, National United University, Miaoli 36063, Taiwan.
³ Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City 81157, Taiwan; Institute of Aquatic Science and Technology, National Kaohsiung University of Science and Technology, Kaohsiung City 81157, Taiwan; College of Fisheries and Allied Sciences, Northern Negros State College of Science and Technology, Sagay City 6122, Philippines.
⁴ Department of Fisheries Production and Management, National Kaohsiung University of Science and Technology, Kaohsiung City 81157, Taiwan.
⁵ Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City 81157, Taiwan. Electronic address: cddong@nkust.edu.tw.

PMID: 37482351
DOI: 10.1016/j.scitotenv.2023.165708

Abstract

Microplastics (MPs) may be underestimated in coral reef sediments. Current pretreatments for determining MPs in the sediments are mainly density separation and organic matter removal, ignoring MPs that may be embedded or encrusted in biominerals. This could lead to discrepancies in assessing the potential risk of MPs contamination. To confirm whether MPs in coral reef sediments are underestimated, a two-step sequential digestion, including organic matter removal (H₂O₂ digestion) and biomineral removal (HCl digestion), was performed on sediments from the coral reef area of the South Penghu Marine National Park (SPMNP, Taiwan). The MPs abundance and characteristics of the two steps were analyzed separately. The results showed that the average MPs abundance after HCl digestion (78 ± 42 MPs/kg) was significantly higher than that of H₂O₂ digestion (38 ± 25 MPs/kg). The MPs diversity integrated index (MPDII) in coral reef sediments was low (MPDII = 0.35), and MPs were mainly small (<2.0 mm, 91.3 %), fibrous (93.5 %), colored (60.9 %), and rayon polymers (73.9 %). Correlation analysis showed that MPs in biominerals mainly dominated MPs in the sediments. These results confirm that current assessments of MPs contamination levels in biomineral-rich sediments may be underestimated and uncertain. In addition, the mineralization of organisms in SPMNP reef regions was affected by MPs from moderate to high levels, depending on the proportion of MPs in biominerals.

Keywords: Biominerals; Coral reef; Microplastics; Sediments; Shell debris.

MeSH terms

Coral Reefs
Environmental Monitoring
Geologic Sediments / analysis
Hydrogen Peroxide / analysis
Microplastics* / analysis
Plastics
Water Pollutants, Chemical* / analysis

Substances

Microplastics
Plastics
Hydrogen Peroxide
Water Pollutants, Chemical