Occurrence characteristics in sediment and bioaccumulation for metal-based nanoparticles in the Yangtze River Estuary-Hangzhou Bay

Environmental exposure of metal-based nanoparticles (MNPs) in coastal area may adversely affect marine organisms. However, the occurrence characteristics and size distributions of MNPs in coastal area remain to be analyzed, and their bioaccumulation pattern in marine organisms is unclear. In this study, pollution levels and size distributions of aluminium, titanium, cerium, zinc, copper, and silver-based nanoparticles (Al-NP, Ti-NP, Ce-NP, Zn-NP, Cu-NP, Ag-NP) in the surface sediments of 29 sampling sites in the Yangtze River Estuary-Hangzhou Bay were analyzed using single-particle inductively coupled plasma mass spectrometry. The results showed that the particle concentrations of MNPs in the sediments of the Yangtze River Estuary-Hangzhou Bay were Al-NP, Ti-NP, Ce-NP, Zn-NP, Cu-NP, Ag-NP in descending order, and the sites with high concentration of Al-NP and Ce-NP were concentrated in the Yangtze River Estuary, while there was no such a pattern for other MNPs. In addition, for the Ti-NP with the largest production volume and the Ag-NP with the widest range of products, this study quantitatively characterized their pollution levels and size distributions in six species of marine mollusks and three species of marine fishes. The results showed that the particle concentrations of Ti-NP in mollusks and fishes (10¹² particles/kg, dry weight) were higher than that of Ag-NP (10⁹ − 10¹¹ particles/kg), and the mean particle sizes of Ti-NP, Ag-NP in mollusks were (71.6 ± 4.5) nm and (37.2 ± 7.4) nm, respectively. By calculating the number-based biota-sediment accumulation factors (NBSAF) of MNPs in marine mollusks, it was found that the NBSAF of Ag-NP was 19.60 ± 8.93, whereas the NBSAF of Ti-NP was 0.98 ± 0.52, suggesting that Ag-NP with a smaller particle size had stronger bioaccumulation in mollusks compared to Ti-NP. In this study, the pollution levels and size distributions of MNPs in sediments and organisms were analyzed. The results provided basic data and theoretical basis for evaluating the marine ecological risk of MNPs.