Research
| Title： | Biofilm-mediated mitigation of N2O emissions in submerged macrophytes area of freshwater lake |
|---|---|
| First author： | Huang, Yongxia; Deng, Min; Jiang, Xiaoyan; Li, Lu; Zhou, Shuni; Wang, Zezheng; Song, Kang; Wu, Fengchang |
| Journal： | CHEMICAL ENGINEERING JOURNAL |
| Years： | 2025 |
| DOI： | 10.1016/j.cej.2025.166896 |
| Abstract： | Submerged macrophytes (SMs) regulate nitrogen cycling in freshwater lakes, but their impact on nitrous oxide (N2O) emissions remains poorly understood. In this study, field investigations were conducted in adjacent SMs (dominated by Vallisneria natans planted at 50-80 plants m(-2)) and non-submerged macrophytes (NSMs) areas within Donghu Lake. The N2O fluxes in the SMs area were - 1.2 +/- 10.1 mu mol m(-2) d(-1), which were significantly lower than those in the NSMs area (8.3 +/- 7.5 mu mol m(-2) d(-1)) (p < 0.01), despite similar concentrations of TAN, NO2--N, NO3--N, TN, TP, and DOC in both areas. Notably, the pH and dissolved oxygen (DO) concentrations in the SMs area were 1.2- and 1.5-fold higher, respectively, than those in the NSMs area, contributing to the observed reduction in N2O emissions. Functional gene analysis revealed that the N2O production potential ((nirK + nirS)/(nosZI + nosZII)) was 2.3 times higher in NSMs biofilm than in SMs biofilm. Thus, biofilms attached to SMs, rather than water or sediment, were primarily responsible for mitigating N2O emissions. The formation of oxic-anoxic microenvironments within SMs biofilm created favorable niches for the nosZII gene and the denitrifier Hyphomicrobium, thereby enhancing N2O reduction. Therefore, restoration of SMs represents a promising nature-based solution for mitigating greenhouse gas emissions in freshwater ecosystems. |
