Low-density polyethylene microplastics and biochar interactively affect greenhouse gas emissions and microbial community structure and function in paddy soil

• Published in: Chemosphere (Oxford) 2023-11, Vol.340, p.139860-139860, Article 139860
• Main Authors: Zhang, Zhiyu, Kang, Yujuan, Wang, Wenfeng, Xu, Lei, Liu, Jiping, Zhang, Zhongsheng, Wu, Haitao
• Format: Article
• Language: English
• Subjects: Acidobacteria; Actinobacteria; Biochar; carbon dioxide; community structure; denitrification; equations; Functional genes; genes; Greenhouse gases; methane; microbial communities; Microbial community; Microplastics; nitrous oxide; paddies; paddy soils; polyethylene; Proteobacteria; soil amendments
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2023.139860

Paddy soils are susceptible to microplastics (MPs) contamination. As a common soil amendment, biochar (BC) has been extensively applied in paddy fields. The co-occurrence of MPs and BC may cause interactive effects on soil biogeochemical processes, which has yet been well studied. In this study, a 41-days of microcosm experiment was conducted using paddy soil added with 0.5–1.5 wt% of low-density polyethylene (LDPE) and 5 wt% of BC individually or jointly. Application of BC, LDPE, or their mixture into soil significantly increased the emission of methane (CH4), but suppressed the emission of carbon dioxide (CO2). LDPE addition lowered soil nitrous oxide (N2O) emissions, while BC exerted an opposite effect. Proteobacteria was the most dominant phylum with a relative abundance range of 35.1–51.0%, followed by Actinobacteria (19.3–30.9%) and Acidobacteria (7.5–23.5%). The abundances of the mcrA gene and pH values were increased in soils added with BC or/and LDPE, which were the possible reasons for the higher CH4 emissions in these treatments. The emission of N2O was positively related to the abundances of norB and narG genes, suggesting denitrification was a major pathway to produce N2O. Results of structural equation modeling demonstrated that addition of BC or/and LDPE MPs could affect greenhouse gas emissions from paddy soil by altering soil chemical properties, microbial community structure, and functional gene abundances. [Display omitted] •LDPE or/and BC additions increased soil CH4 emissions, but suppressed CO2 fluxes.•Addition of LDPE decreased soil N2O emissions, while BC exerted a promoting effect.•Proteobacteria dominated the soil bacterial communities under different treatments.•The increased pH values and higher mcrA gene abundance promoted soil CH4 emissions.•Denitrification played an important role in regulating soil N2O emissions.