The impact of microplastics (MPs) on humans is receiving increasing attention. This is a class of plastic fragments or particles with a particle size of less than 5mm, widely found in water and terrestrial environments, and can be used as a carrier of various toxic pollutants such as metal ions. Microplastics can be ingested directly or indirectly by organisms and transmitted and enriched on the food chain, threatening ecosystem functions and human health.
The surface of microplastics often interacts with heavy metals and other pollutants, which become the carrier of other pollutants entering the organism. Due to the presence of intestinal surfactants in animals, these heavy metals that are adsorbed to the surface of microplastics are prone to desorption in organisms, a process that may lead to higher ecological risks.
However, although the adsorption characteristics of heavy metals in microplastics have been studied, the desorption behavior of heavy metals in microplastics in different environments is still very unknown. This means that, at present, the desorption behavior of heavy metals on the surface of microplastics and its ecological risks under different environmental conditions are not yet clear.
Recently, the research team of the Wuhan Botanical Garden of the Chinese Academy of Sciences published a study in the academic journal Water Research entitled “Adsorption mechanism of cadmium on microplastics and their desorption behavior and the sturs of the gut s: The role of the water water pH, lead ions, natural organic matter and phenanthrene.” Zhou Yanfei, a doctoral student at Wuhan Botanical Garden of the Chinese Academy of Sciences, is the first author of the study and researcher Liu Wenzhi is the author of the paper.
Based on the pre-work on the toxic effects of microplastic composite pollution on radon, the research team further studied the adsorption capacity of microplastics to heavy metal cadmium Cd (II) and the desorption behavior of cadmium in different environmental media with five microplastics (PA, PVC, PS, ABS and PET) as the object.
The results showed that polyamide microplastics (PA) had the highest adsorption capacity to cadmium, at 1.70 to 0.04 mg/g, followed by PVC (PVC) at 1.04 to 0.03 mg/g, and polystyrene (PS) at 0.76 x 0.02 mg/g, acrylonitrile-butadiene-styrene (ABS) is 0.65 mg/g, polyphenyl ethylene glycol (PET) is 0.25 to 0.01 mg/g.
The study also found that the ability of microplastics to adsorption of cadmium was influenced by pH, humic acid and other heavy metal ions such as lead concentrations. The presence of rotting phytic acid in water will promote cadmium to be desorption from the surface of microplastics, and the destructrate rate of cadmium in animal intestines is 36.9%-59.9%, which is much higher than the cadmium desoration rate of 6.9%-18.7% in the bottom mud environment.
The research team pointed out that the study showed that microplastics in the natural environment are eaten by animals, the surface of heavy metal pollutants have a greater anti-adsorption rate and ecological risks. Overall, they say, the study will help to better understand the mechanism of cadmium adsorption to microplastics and the desorption behavior of different environmental conditions in aquatic ecosystems.