Microplastics are ubiquitous in natural waters and affect the environmental fate of hydrophobic organic micropollutants. This study evaluated the impacts of four microplastics, polypropylene (PP), polyethylene (PE), polystyrene (PS) and polymethyl methacrylate (PMMA), on the photodegradation of organotin compounds (OTCs) under UV₃₆₅ irradiation (2.3 ± 0.1 W·m^-2). The experiments were performed by mixing PP, PE, PS or PMMA microparticles with tri-organotins in artificial seawater. The photodegradation of OTCs in microplastic suspensions was influenced by the absorptivity onto microplastics. The decomposition rate of tributyltin (TBT) in UV-irradiated PP suspensions was greater than trimethyltin (TMT) and triphenyltin (TPhT) (p < 0.01). The adsorption capacities of OTCs (e.g., TBT) on PP particle surfaces were significantly lower than those on PE surfaces (p < 0.05) but similar with those on PMMA due to the different surface areas, shapes, and surface hydrophobicity of microplastics. TBT degraded faster (9.1%) in PS than in PMMA suspension (11.2%) within 240 min, respectively. However, only less than 5.4% was photodegraded in PP suspension due to the light scattering or absorption of the large sized PP particles. This study provided new insight into the impacts of microplastics on photodegradation of micropollutants in natural waters.

微塑料在自然水中无处不在，并影响疏水性有机微污染物的环境命运。这项研究评估了聚丙烯（PP），聚乙烯（PE），聚苯乙烯（PS）和聚甲基丙烯酸甲酯（PMMA）四种微塑料对UV ₃₆₅辐照（2.3±0.1 W·m ）下有机锡化合物（OTC）的光降解的影响。^-2）。通过在人造海水中将PP，PE，PS或PMMA微粒与三有机素混合来进行实验。微塑料悬浮液中OTC的光降解受到微塑料吸收率的影响。紫外线辐照的PP悬浮液中三丁基锡（TBT）的分解速率大于三甲基锡（TMT）和三苯基锡（TPhT）（p<0.01）。PP颗粒表面的OTC（例如TBT）吸附能力明显低于PE表面（p <0.05），但由于微塑料的表面积，形状和表面疏水性不同，它们与PMMA相似。在240分钟内，PS中的TBT降解速度比PMMA悬浮液中的降解速度更快（9.1％）（11.2％）。然而，由于大尺寸PP颗粒的光散射或吸收，在PP悬浮液中仅光降解不到5.4％。这项研究提供了新的见解，对微塑料对自然水中微污染物的光降解的影响。