Polyethylene microplastic and nano ZnO Co-exposure: Effects on peanut (Arachis hypogaea L.) growth and rhizosphere bacterial community

Micro: and nano-pollutants are receiving increased research attention. However, the effects of the interactions and co-exposure to these pollutants in soil are yet to be fully elucidated. This work aimed to investigate the effects of co-exposure to polyethylene microplastics (PEMPs) and nano-ZnO (nZnO) in soil on the growth, nutrient uptake, and distribution of the peanut (Arachis hypogaea L.) and soil microbial community. Results revealed that 500 mg kg-1 nZnO significantly decreased the dry weight of peanut root, stem, leaf, and fruit by 84.4%, 79.1%, 87.3%, and 95.8%, respectively, compared with the control. Co-exposure treatments significantly alleviated this trend. Co-exposure treatments further decreased Zn concentration in peanuts by 30.3%-58.9% compared with nZnO single exposure. The distribution of Zn in peanut stems also maintained a consistent trend with the concentration and primarily occurred in the vascular bundles near the epidermis. Co-exposure and PE treatments increased the abundance of soil bacteria primarily because many PE particles entered the soil to build more living space for bacteria. These findings showed that composite pollution had a robust disturbing effect on the soil-peanut system, and the two pollutants were primarily physically adsorbed. PE particles can adsorb nZnO and then become the carrier of nanoparticles.