The effect of N mineralization, nitrification and ammonification rates in soils contaminated with microplastics

Abstract

Microplastics (MPs) have emerged as a pervasive environmental pollutant, posing significant threats to both aquatic and terrestrial ecosystems. Despite the growing concern, research on the impacts of MPs on soil ecosystems, particularly on crucial processes like nitrogen cycling, remains limited compared to aquatic environments. This study aimed to fill this knowledge gap by conducting a 60-day incubation experiment to investigate the effects of polypropylene (PP), polyethylene (PE), and polyethylene terephthalate (PET) microplastics on soil nitrogen transformation processes. The findings revealed that microplastic contamination influenced soil nitrogen dynamics, with PP having the most detrimental impact. Specifically, the ammonification rate was consistently lower than the nitrification potential, and although the nitrification potential was not negatively affected by the presence of MPs, the availability of soil nitrogen, particularly in the form of nitrate, was predominantly maintained. However, at the end of the incubation period, soils contaminated with PP showed a significant reduction in available nitrogen concentrations. Generally, it was found that PP had the most negative effect on soil nitrogen processes. These results underscore the varying effects of different types of microplastics on soil nitrogen processes, highlighting the critical need for further investigation into their long-term environmental impacts.