Microplastics (MPs) and heavy metals are two major types of pollutants that interact with each other, but they are poorly understood. Polystyrene (PS) is a type of MP that is often detected in aquatic environments. In this study, we examined the adsorption capacity and release rate of heavy metals with respect to different particle sizes of PS, heavy metals, initial heavy metal concentrations, and salinities. Virgin (new) PS with diameters of 20, 50, 130, and 250 µm was used in this study, and four heavy metals (lead, cadmium, copper, and zinc) were used. The results showed that larger PS particle sizes adsorbed more heavy metals even though it took longer to achieve equilibrium adsorption. An increase in heavy metal concentration caused the adsorption capacity (µg/g) of PS particles to also increase, but the adsorption rate (%) decreased. Increased salinity of the heavy metal solution resulted in a slower adsorption time and a lower adsorption capacity and release rate from the surface of PS particles. Different heavy metals also had different adsorption capacities. Pb was consistently more highly adsorbed by MPs, followed by Cu, Zn, and Cd. Larger PS sizes released heavy metals faster than smaller PS sizes, and the amounts of heavy metals released were higher. The heavy metal with the highest release rate was Cd, followed by Pb, Cu, and Zn. Finally, our findings highlight the interactions between PS and heavy metals and strongly support that PS particles can act as vectors for heavy metals in aquatic systems.

中文翻译：

---

重金属在各种盐度下在聚苯乙烯（PS）颗粒上的吸附和释放

微塑料（MPs）和重金属是相互影响的两种主要污染物，但人们对其了解甚少。聚苯乙烯（PS）是一种MP，通常在水生环境中被检测到。在这项研究中，我们检查了相对于PS，重金属，初始重金属浓度和盐度的不同粒径，重金属的吸附能力和释放速率。在这项研究中，使用了直径为20、50、130和250 µm的维珍（新）PS，并使用了四种重金属（铅，镉，铜和锌）。结果表明，较大的PS颗粒吸附了更多的重金属，即使达到平衡吸附所需的时间更长。重金属浓度的增加导致PS颗粒的吸附容量（µg / g）也增加，但吸附率（％）降低。重金属溶液盐度的增加导致吸附时间变慢，吸附能力和从PS颗粒表面释放的速率降低。不同的重金属也具有不同的吸附能力。始终一致地，MP吸附的铅更高，其次是Cu，Zn和Cd。较大的PS释放的重金属比较小的PS释放的快，重金属的释放量也更高。释放速率最高的重金属是Cd，其次是Pb，Cu和Zn。最后，我们的发现突出了PS和重金属之间的相互作用，并强烈支持PS颗粒可以作为水生系统中重金属的载体。不同的重金属也具有不同的吸附能力。始终一致地，MP吸附的铅更高，其次是Cu，Zn和Cd。较大的PS释放的重金属比较小的PS释放的快，重金属的释放量也更高。释放速率最高的重金属是Cd，其次是Pb，Cu和Zn。最后，我们的发现突出了PS和重金属之间的相互作用，并强烈支持PS颗粒可以作为水生系统中重金属的载体。不同的重金属也具有不同的吸附能力。一直以来，MP吸附的铅含量更高，其次是Cu，Zn和Cd。较大的PS释放的重金属比较小的PS释放的快，重金属的释放量也更高。释放速率最高的重金属是Cd，其次是Pb，Cu和Zn。最后，我们的发现突出了PS和重金属之间的相互作用，并强烈支持PS颗粒可以作为水生系统中重金属的载体。