Microplastics are widespread contaminants originating from diverse sources, following numerous environmental pathways, and accumulating in various sinks. As plastics weather over time, surface features such as labels and branding deteriorate or are entirely lost, and the items often fragment into particles that no longer resemble their original form. Once released into the environment, determining the original application or tracking the movement history of microplastics becomes extremely challenging. Nevertheless, tracing the origin and production source of plastic debris is critical for addressing mismanagement, identifying emission hotspots, locating interception opportunities, and informing effective policy strategies.
This study explored the use of protein signatures within the ecocorona to retrospectively trace microplastics across environmental contexts. As a proof of concept, various plastics—either pristine or coated with bovine serum albumin (BSA)—were deployed in a marine tank containing Penaeus monodon, and the resulting ecocorona proteomes were quantified. We further applied this approach to investigate biomedia plastics unintentionally discharged into the marine environment from the waste sump of an aquaculture facility in Queensland, Australia.
To generate a robust species-specific protein reference for data-independent acquisition (DIA) quantification, we combined eDNA metabarcoding, conventional proteomic workflows, and de novo peptide sequencing, using Unipept 2.0 and NCBI BLASTp for protein assignment.
Our results showed that polymer type influenced total protein adsorption, and the ecocorona on pristine plastics in tanks closely reflected the surrounding seawater proteome. In contrast, biomedia beads exhibited distinct microbiome and proteome profiles depending on their collection site. Notably, we identified several unique indicator species within the ecocorona of beach-collected biomedia that matched taxa from the aquaculture facility, confirming their source. These findings demonstrate the potential of ecocorona-based source tracking for microplastics, particularly over short environmental transit times.