Size Effects of Polyethylene Microplastics on the Degradation of Phenanthrene and Bacterial Communities in Agricultural Soils
Polycyclic aromatic hydrocarbons(PAHs)are accumulating in agricultural soil,and microbial degradation is an ideal pathway for PAHs attenuation.Recent studies have shown that the physicochemical properties of microplastics(MPs),as emerging pollutants,have a significant influence on the biodegradation process of PAHs.In this study,we focused on the interaction of polyethylene(PE)microplastics with a typical PAH,phenanthrene(PHE),and selected PE microplastics(PE-MPs)with different particle sizes(550 μm,150 μm,and 13 μm)and exposure concentration of l％(w)as the research ob-jects.The effects of PE-MPs particle size changes on the degradation efficiency of PHE and bacterial community structure in soil were systematically investigated through a 42-day simulated incubation experiment in agricultural soil.The results showed that PE-MPs significantly inhibited the natural degradation process of PHE,and the inhibition was intensified with the decrease of PE-MPs particle size.Specifically,compared with the nearly complete degradation rate(99.95％)in the control group,the degradation rate of PHE in the 13 μm particle size PE-MPs group significantly decreased to 94.05％(P＜0.05).Further analysis showed that this inhibitory effect might originate from the fact that PE-MPs reduced the bioavailability of PHE and directly affected the number and activity of microbial populations involved in PHE degradation in the soil.In addition,PE-MPs with different particle sizes also indirectly interfered with the biodegradation of PHE by changing the bacterial community composition and physicochemical properties of the soil.In summary,PE-MPs significantly hindered the biodegradation of PHE by reducing the bioavailability of PHE and altering the structure of soil microbial community,and this inhibitory effect became more and more significant with the decrease of PE-MPs particle size.This finding not only deepens the understanding of the ecological effects of the composite pollution of microplastics and PAHs,but also provides an impor-tant scientific reference for the future ecological risk assessment and bioremediation technology development for the compos-ite contaminated soil.
万方数据
维普
