Impacts of quaternary ammonium compounds on the ecological risks of cadmium, enzyme activities, and bacterial community in soils

• Published in: Environmental technology & innovation 2025-02, Vol.37, p.104047, Article 104047
• Main Authors: Li, Jie, Chen, Haiyan, Zi, Fengrui, Wu, Zhangqian, Li, Wenxing, Duan, Qigang, Song, Haoran, Huang, Jianhong, Zhao, Qun, Hu, Xuewei, Tian, Senlin
• Format: Article
• Language: English
• Subjects: Cadmium; Co-exposure; Enzyme activity; Quaternary ammonium compounds; Soil microorganisms
• ISSN: 2352-1864; 2352-1864
• DOI: 10.1016/j.eti.2025.104047

During the COVID-19 pandemic, a worldwide surge in quaternary alkylammonium compound (QAC) use resulted in QAC and cadmium (Cd) complexation in soil. However, the environmental risks posed by the coexistence of QACs and Cd in soils remain unclear. In this study, three QACs were selected to investigate the influences of the co-occurrence of individual and combined QACs with Cd in 30–day long indoor incubation experiments on the ecological risks of Cd, enzyme activities, and bacterial communities in soils. The presence of QACs increased the ecological risk index and leachability of Cd by 4.13–23.90 % and 0.90–6.93 %, respectively, compared to the control. The increase in the risk index and Cd leachability was more pronounced under combined QAC co-exposure. Adding QACs resulted in decreases in the soil NH4+-N content and activity of ammonia monooxygenase, nitrate reductase, and nitrite reductase, which are closely related to soil nitrification and denitrification. Coexisting QACs and Cd decreased bacterial richness and evenness, decreased the abundances of Proteobacteria, Bacteroidota, and Actinobacteriota, and increased the abundance of Firmicutes. The nature of QACs influenced the toxicity of these chemicals to soil bacteria, as reflected by the changes in the dominant genera and microbial biomarkers when different QACs were added. Compared to Cd-only-treated soils, QAC addition led to an intricate microbial relationship, with NH4+-N and soil nitrite reductase activity identified as key environmental variables shaping soil bacterial communities. These results provide valuable insights for managing the potential risks of emerging complex scenarios in agricultural activities. [Display omitted] •QACs increased the ecological risk index and leachability of soil Cd.•QACs negatively influenced soil enzyme activities associated with N cycling.•QACs decreased the diversity and richness of the soil microbial communities.•QAC toxicity to soil bacteria is related to its molecular structures.