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

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.