Effect of Zinc Oxide Nanoparticles on Nitrous Oxide Emissions in Agricultural Soil

Ziyi Feng,Huaiying Yao,Chaorong Ge,Yongxiang Yu

doi:10.3390/agriculture11080730

Ziyi Feng, Huaiying Yao + Show 2 more

Open Access

https://doi.org/10.3390/agriculture11080730

Copy DOI

Abstract

Zinc oxide nanoparticles (ZnO NPs) are widely used and exposed to the soil environment, but their effect on soil nitrous oxide (N2O) emissions remains unclear. In this study, a microcosm experiment was conducted to explore the effects of different ZnO NPs concentrations (0, 100, 500, and 1000 mg kg−1) on N2O emissions and associated functional genes related to N2O amendment with carbon (C) or nitrogen (N) substrates. Partial least squares path modeling (PLS-PM) was used to explore possible pathways controlling N2O emissions induced by ZnO NPs. In the treatment without C or N substrates, 100 and 500 mg kg−1 ZnO NPs did not affect N2O production, but 1000 mg kg−1 ZnO NPs stimulated N2O production. Interestingly, compared with the soils without ZnO NPs, the total N2O emissions in the presence of different ZnO NPs concentrations increased by 2.36–4.85-, 1.51–1.62-, and 6.28–8.35-fold following C, N and both C & N substrate amendments, respectively. Moreover, ZnO NPs increased the functional genes of ammonia-oxidizing bacteria (AOB amoA) and nitrite reductase (nirS) and led to the exhaustion of nitrate but reduced the gene copies of ammonia-oxidizing archaea (AOA amoA). In addition, the redundancy analysis results showed that the AOB amoA and nirS genes were positively correlated with total N2O emissions, and the PLS-PM results showed that ZnO NPs indirectly affected N2O emissions by influencing soil nitrate content, nitrifiers and denitrifiers. Overall, our results showed that ZnO NPs increase N2O emissions by increasing nitrification (AOB amoA) and denitrification (nirS), and we highlight that the exposure of ZnO NPs in agricultural fields probably results in a high risk of N2O emissions when coupled with C and N substrate amendments, contributing to global climate warming.

Highlights

In the past few decades, engineered nanoparticles (NPs) have been widely used in industrial, agricultural, and consumer production due to their unique properties [1,2]
Our findings showed that Zinc oxide nanoparticles (ZnO NPs) accelerated the release of N2O from soils after C or N substrate amendment
The interaction of C and N caused the total N2O emissions to substantially increase by 6.28–8.35 times compared with the control treatment without Zinc oxide (ZnO) NPs

Summary

Introduction

In the past few decades, engineered nanoparticles (NPs) have been widely used in industrial, agricultural, and consumer production due to their unique properties (such as antibacterial properties) [1,2]. Most consumed NPs are exposed to the soil environment through the application of wastes and sewage sludge, which causes potential risks for microorganisms due to their toxic effects [3,4]. The toxic action of ZnO NPs or the dissolution of Zn2+ can decrease soil microbial activity related to nitrogen (N) cycling [12,13,14,15] and N mineralization efficiency [14], which indirectly reduces N2O emissions. Few studies have focused on the impact of ZnO NPs on N2O emissions. Durenkamp et al [19] observed that combining ZnO and Ag NPs has a minimal impact on N2O emissions in soil/sewage sludge mixtures. Rashid et al [14] found that ZnO NPs reduced the nitrogen mineralization of leaf litter in sandy soil and probably reduced the release of N2O

Methods

Results

Discussion

Conclusion