Mechanism of nanoplastics altering soil carbon turnover under freeze-thaw cycle
Guankai Qiu, Meixuan Wu, Zhongxu Duan, Nannan Li, Chuanzhong Zhang, Jingying Wang, Jing Yue, Quanying Wang, Hongwen Yu, Hongwen Yu
Abstract
Nanoplastics (NPs) affect soil carbon (C) turnover, but their influence on this process through modifications in soil aggregate stability under freeze-thaw cycles remains unclear. In this study rare earth oxides (REOs) and C isotope ( 13 C) labeling, combined with Soil Microstructure Scanning Computed Tomography (SMS-CT) and data modeling, were used to examine the relationship between soil aggregate turnover and C turnover under NPs. Compared with the control group, the total phase porosity and surface area of soil treated with NPs increased by 11.9 % and 30.9 %, respectively under freeze-thaw cycle. NPs exhibited a positive effect on the stability of soil aggregates, and the change in soil aggregate stability were attributed to shifts in aggregate composition. During the freeze-thaw cycle, the distribution of 13 C in 0.5–1 mm aggregates decreased by 41.9 % compared with the control group, while it increased by 60.8 % in < 0.25 mm aggregates, indicating NPs redirected C toward microaggregates . Freeze-thaw cycles improved the connection between soil aggregates and C turnover, whereas NPs increased resistance of aggregate to freeze-thaw forces. This study provides new insights into the environmental effects of NPs on soil ecosystems and food security.