Distribution, bioaccumulation, and trophic transfer of palladium-doped nanoplastics in a constructed freshwater ecosystem

The widespread occurrence of nanoplastics (NPs) warrants a critical evaluation of their environmental behaviors in aquatic food webs. However, due to the challenges of quantifying NPs and their complexity in the real environment, our understanding of NPs' fate in aquatic ecosystems is rather limited. Herein, Danio rerio, Echinolittorina lineolata, Corbicula fluminea, Sergia lucens, Ceratophyllum demersum, Salvinia natans, freshwater, and sediment were used to build a freshwater ecosystem to quantitatively investigate NP distribution, bioaccumulation, and trophic transfer via pulse and chronic exposures to palladium (Pd)-doped NPs for 49 days. NP concentrations were continuously monitored based on Pd concentrations determined by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion. We observed that most of the NPs were deposited in the sediment (>= 94.5%). The total bioaccumulated NPs averaged 3.34% and 0.40% of the administered dose for the chronic- and pulse-treatment groups, respectively, suggesting that NPs may be more bioavailable through chronic exposure than pulse exposure. Additionally, the bioaccumulated NPs in the tested biota species were negatively correlated with the trophic levels, suggesting no NP biomagnification in the constructed microcosm. To our knowledge, this is the first report on quantitatively tracking NP behaviors in aquatic ecosystems, providing important insights into their risk assessment.