Microorganism structure variation in urban soil microenvironment upon ZnO nanoparticles contamination

Nanoparticles (NPs) sink into the soil via agricultural spreading, surface water, atmospheric deposition, and industrial emission, which affects plant growth and soil microenvironment. To understand how NPs influence urban soil microenvironment, the effect of typical nano-pollutants zinc oxide nanoparticles (ZnONPs) was investigated in urban solid-waste land. Pokeweed (Phytolacca Americana L.) soil samples from solid-waste land were collected and exposed to 200, 500, and 1000 mg kg^-1 ZnONPs. The physiological characteristics of pokeweed, soil bacterial community composition, and soil physiochemical properties and enzymatic activities were determined. Our results show that pokeweed growth was slightly inhibited, and soil acid-base homeostasis was affected in ZnONPs-contaminated samples. Meanwhile, enzymatic activities related to soil C cycle were enhanced, and bacterial community structure at the phylum and genus levels was altered. Specifically, the abundance of hydrocarbon-degrading taxa reduced substantially upon ZnONPs exposure. The phenoloxidase (PPO) activity and the refractory hydrocarbon-degrading bacteria Bacteroidetes was adversely affected by ZnONPs exposure. In addition, Subgroup_10 of Acidobacteria was identified as an indicator of soil ZnONPs contamination. Our study detected changes in plant growth, soil environmental factors, and soil microbe community composition in urban solid-waste land treated by ZnONPs. The results of this research provide evidence for ZnONPs toxicology on urban soil microenvironment.