Development of a digestion method for determining microplastic pollution in vegetal-rich clayey mangrove sediments

Jiehan Duan; Jie Han; Haichao Zhou; Yat Long Lau; Wenwen An; Pingping Wei; Siu Gin Cheung; Yang Yang; Nora Fung-Yee Tam

doi:10.1016/j.scitotenv.2019.136030

Development of a digestion method for determining microplastic pollution in vegetal-rich clayey mangrove sediments

Sci Total Environ. 2020 Mar 10:707:136030. doi: 10.1016/j.scitotenv.2019.136030. Epub 2019 Dec 9.

Authors

Jiehan Duan¹, Jie Han², Haichao Zhou³, Yat Long Lau², Wenwen An³, Pingping Wei³, Siu Gin Cheung⁴, Yang Yang⁵, Nora Fung-Yee Tam⁶

Affiliations

¹ Institute of Hydrobiology, Jinan University, Guangzhou 510632, China.
² School of Science and Technology, The Open University of Hong Kong, Hong Kong, China.
³ College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, China.
⁴ Department of Chemistry and State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
⁵ Engineering Research Center of Tropical and Subtropical Aquatic Ecological Engineering, Ministry of Education, Guangzhou, China.
⁶ Department of Chemistry and State Key Laboratory in Marine Pollution, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China. Electronic address: bhntam@cityu.edu.hk.

PMID: 31869617
DOI: 10.1016/j.scitotenv.2019.136030

Abstract

Microplastics are ubiquitous pollutants found in environments. Mangrove sediments containing vegetal litter are different from other environmental matrices such as river and marine sediments. The presence of vegetal litter leads to an under-estimation of microplastic pollution, particularly classical digestion methods are not suitable for removing this type of organic matter. The present study aims to develop a digestion method to remove vegetal litter and improve the determination of microplastic pollution in mangrove sediments. Results showed that our three-stage method with repeatedly addition of hydrogen peroxide had the highest efficiency in removing mangrove vegetal litter when compared with the three classical digestion methods. The high match scores of Fourier Transform Infrared Spectroscopy proved that the developed method had little impacts on the integrity of five polymer types of microplastics. The developed method also achieved high efficiency in extracting microplastics from mangrove sediments containing different content of vegetal litter. CAPSULE: A digestion method was developed for extracting microplastics in clayey mangrove sediments rich in vegetal litter.

Keywords: Mangrove sediment; Microplastics; Step-wise digestion; Vegetal litter.