Microplastics aging degradation behaivor in urban road surface sediments under UV irradiation and high temperature exposure

Recently, increasing attention has been paid to microplastics (MPs) in road surface sediments. However, there is still no available literature about MPs aging degradation of road surface sediments under Ultraviolet (UV) irradiation and high temperature exposure. Batch experiments were conducted to investigate aging degradation behavior of MPs in urban road surface sediments under the mentioned environmental conditions. Aging degradation efficiency of MPs s howed that the aging degradation efficiency of MPs got to the peak at 25 Wm ^− 2 UV light intensity or 65°C exposure alone for 4h with 38.81% and 41.93%, respectively, which was less than the one (68.91%) under the combined action between UV irradiation and high temperature exposure. Aging degradation kinetics of MPs indicated that high temperature exposure could promote the aging degradation of MPs through UV irradiation with the largest constants of 0.101 h ^− 1 (Pseudo-first-order kinetic) and 7.310 g ⁻¹ h ^− 1 (Pseudo-second-order kinetic). The effect of particle size distribution of MPs hinted that there were the highest correlation coefficients of MPs aging degradation efficiency with MPs quantity reduction rate in sizes of 200–300 µm and 400–500 µm, with 0.932 (p = 0.236) and (0.668, p = 0.535), respectively, suggesting that controlling MPs with the above sizes during the fine weather in summer was particularly crucial. The role of dissolved organic matter signified that Protein-like components in road surface sediments could be related to MPs aging degradation.