Evaluation of nano-silver concentrations using multi-media fate and transport models with different spatial...

Due to the complexity of the environmental matrix and the limitation of the detection level, it is important to use models to evaluate environmental exposure to nanomaterials. Based on this, this research established two multi-media fate and transport models of silver nanoparticles (AgNPs) with respective coarse and fine spatial resolutions. Using the case of the spatial distribution of AgNPs in the Xiangjiang River, China, we compared how the spatial resolution of a model impacts modeling results. The results show that the process of heterogeneous aggregation has the greatest impact on the modeled concentration of AgNPs in water, and the heterogeneous aggregation of free AgNPs with natural colloids and settling down to sediments is the dominant mechanism responsible for the loss of AgNPs. In addition, the use of different spatial resolutions gives similar trends in the modeled AgNPs concentration, despite the difference in absolute levels. Our work also shows that the reliability and accuracy of the rate constant of heterogeneous aggregation has a great influence on the modeled AgNPs concentrations.