Study on the effect of biochar addition on ammonia emission from constructed wetlands——Based on the analysis of microbial community assembly mechanism
This study investigated the impact and mechanisms of different biochar ratios on the denitrifiication performance and ammonia emission reduction in surface flow constructed wetlands based on mesocosm simulations.Employing machine learning and"infer Community Assembly Mechanisms by Phylogenetic bin-based null model"(iCAMP),we further explored the microbiological mechanisms involved.The results indicated that,compared to the control group without biochar,a 50％biochar addition significantly promoted the growth of ammonia-oxidizing bacteria(e.g.,Chloroflexi,Rhodocyclaceae),enhanced NH4+-N transformation in the system,and effectively reduced ammonia emissions by 32％.Sensitive microbial species identified by the random forest model,such as Planctomycetes and Parcubacteria,could serve as preliminary indicators for ammonia volatilization flux.The proportion of biochar in constructed wetlands was closely linked to changes in community structure.An increase in biochar ratio led to a clustering of phylogenetic structures and promoted the growth and establishment of specific bacterial communities(e.g.,Gammaproteobacteria,Deltaproteobacteria)related to carbon and nitrogen cycling.This study offers a new perspective on understanding the factors driving microbial communities in constructed wetlands and provides guidance for the practical application of biochar in these ecosystems.
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