Transport Mechanisms of Nanoplastics in Agricultural Soils Under Snowmelt Infiltration Conditions in Cold Regions

Abstract This study was conducted to uncover the migration characteristics of nanoplastics (NPs) permeating with snowmelt water in freeze‐thaw soil and their regulatory mechanisms. Luvisol (LCK), chernozem (CCK), and albic soil (ACK) were selected as porous media, and two scenarios of tetracycline and tetracycline plus biochar were established (LTL and LTLB for luvisol, CTL and CTLB for chernozem, and ATL and ATLB for albic). With snowmelt infiltration, soil NPs concentration in the CCK treatment had a peak value of 25.62 mg kg −1 in the vertical profile, whereas the ACK and LCK treatments were 5.32% and 7.79% higher than the CCK treatment, respectively. The presence of tetracycline and biochar provided additional adsorption sites for NPs, which in turn promoted the deposition and sequestration effects of NPs. This research constructed an innovative migration model of soil NPs under snowmelt infiltration and confirmed that soil NPs would be strongly resolved and re‐migrate under extreme snowfall. Moreover, the NPs in the chernozem would reach 2.12 mg kg −1 at the vertical profile crest after 20 years, which is 6.19% and 19.88% lower relative to the albic soil and luvisol, respectively. Finally, the Extended Derjaguin‐Landau‐Verwey‐Overbeek (XDLVO) theory measurements demonstrated that the energy barrier heights of the ATL and ATLB treatments in albic soil were 16.80% and 36.91% lower than the ACK treatment, respectively. The lower height of the energy potential barrier makes NPs more accessible to soil particles, which reconfirms that the presence of biochar coupled with tetracycline mediation can effectively inhibit the dissociation release characteristics of soil NPs.