The use of fertilizer is a routine method of soil improvement, and thereby fertilizer is considered as an emerging factor affecting the transport of plastic particle in agricultural soils. Nano-CaCO₃ was selected as representative of nano-fertilizer to investigate its effect on the transport and release of nano- and micro-plastics (NPs and MPs) in saturated porous media. 200 mg L^-1 nano-CaCO₃ on the transport of nano- (0.51 μm, PS NPs) and micro- (1.1 μm, PS MPs) polystyrene particles (5 mg L^-1) in saturated quartz sand were investigated. Nano-CaCO₃ facilitated both the transport and release of PS NPs and MPs under examined 0.1-10 mM NaCl and 0.1-1 mM CaCl₂ solutions. In addition, it was believed that the deposition of PS NPs and MPs with nano-CaCO₃ copresent and release treatment was solid and stable, as verified by the negligible detachment of PS NPs and MPs with deionized water wash. Further investigation indicated that the competition for deposition sites on quartz sand surfaces by nano-CaCO₃ copresent in solutions was the major factor dominating the enhanced transport of both PS NPs and MPs. It was verified by the transport of single nano-CaCO₃, the increased transport of PS NPs and MPs in quartz sand that was subjected to pre-equilibration with nano-CaCO₃ and also the SEM images of quartz sand covered with nano-CaCO₃. Meanwhile, the sweeping effects induced by nano-CaCO₃ were found to be responsible for the enhanced release of PS NPs and MPs during the transport process. It was further confirmed by the relative high surface area, roughness of nano-CaCO₃ and the morphology of effluents of PS NPs and MPs released induced by nano-CaCO₃ by fluorescent microscopy imaging. The findings of this study give insights to assess the ecological risks of plastic particles with agrochemicals.

Nanoplastics, microplastics, nano-fertilizer, transport, release, quartz sand