Microplastics and accumulated heavy metals in restored mangrove wetland surface sediments at Jinjiang Estuary (Fujian, China)

Microplastics have received widespread attention as an emerging contaminant, but limited information was available during wetland restoration. The occurrence and characteristics of microplastics and their interaction with heavy metals in surface sediments from the Jinjiang Estuarine restored mangrove wetland were investigated. The abundance of microplastics ranged from 490 +/- 127.3 to 1170 +/- 99.0 items/500 g dry sediment, and the restored regions were much higher than mudflats, indicating mangrove restoration promoted its accumulation. Polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) were the main materials of microplastics after Raman spectroscopy identification. SEM-EDS images illustrated the mechanical erosion and chemical weathering on microplastics' surface, and Cr, Zn, Pb, and Cd were observed in elemental composition. The contents of Cr, Ni, Cu, Zn, Pb, As, and Cd accumulated in microplastics were not correlated with their total concentrations in sediments except for Hg, indicating that they might not be derived from sediments.