Microplastics, deﬁned as small plastic particles with a size of < 5mm, can originate from breakdown of larger plastic debris, or may be manufactured plastics with a microscopic size, such as industrial pellets and scrubbers in personal care products. The small-sized plastic particulates are ubiquitous aquatic environments. They are chemically stable and can exist in the environment for hundreds of years.
Due to the large surface area, microplastics can concentrate a considerable amount of persistent pollutants, such as heavy metals and hydrophobic organic chemicals from the ambient water. A better knowledge of partition characteristics of environmental pollutants within microplastics is indispensable for properly evaluating the risk of microplastics to the ecosystems.
Under the guidance of Prof. WANG Jun, Dr. WANG Wenfeng from Wuhan Botanical Garden carried out an investigation into partition behavior of phenanthrene (Phe) on miroplastics (including polyethylene, polystyrene and polyvinylchloride) and took the natural sedimentas a comparison.
The sorption affinities of Pheonto the four kinds of solid particles followed an order of polyethylene> polystyrene> polyvinylchloride> natural sediment. The sorption kinetics was successfully described by the pseudo-second-order model while the equilibrium data were best-ﬁtted to the Langmuir isotherm. Increasing addition of pyrene exerted an enhanced negative eﬀect on the uptake of Phe by the solid phases.
Compared with natural sediment, contaminated microplastics could release large amounts of Phe during the desorption process, although their desorption rates might be much lower. These indicated that microplastics were potential sources and sinks of environmental pollutants.
This study was supported by Funding Project of Sino-Africa Joint Research Center, Chinese Academy of Sciences, the Hundred Talents Program of the Chinese Academy of Sciences and Natural Science Foundation of Hubei Province of China.
Results were published in Ecotoxicology and Environmental Safety entitled “Diﬀerent partition of polycyclic aromatic hydrocarbon on environmental particulates in freshwater: Microplastics in comparison to natural sediment”.
SEM images of polystyrene, polyvinylchloride, polyethylene and natural sediment particles (Image by WANG Wenfeng)