微塑料对土壤N_(2)O排放及氮素转化的影响研究进展

Advances in the Effects of Microplastics on Soil N_(2)O Emissions and Nitrogen Transformation

微塑料(MPs)在土壤环境中的作用和影响逐渐受到关注,但其对土壤氮素循环及其影响机制并不明确.氧化亚氮(N2O)是农田土壤氮素循环中重要的温室气体之一,其主要来源于微生物参与的氮转化过程.微塑料对土壤氮转化过程及相关功能酶和基因都能够产生影响,其在土壤中不断富集可能造成土壤N_(2)O排放规律的改变.由于微塑料自身的复杂性以及不同试验在时空上的变异,导致微塑料对土壤氮素转化和N_(2)O排放产生不同了影响,增大了对土壤N_(2)O排放和土壤氮素转化的评估难度.目前,微塑料在土壤N_(2)O排放、氮素含量、相关功能酶活性和功能基因丰度的研究上未得出统一的结论,缺少在更广的尺度(如盆栽尺度)、更多元的角度(如反硝化过程、DNRA过程等)和更先进的手段上(如同位素技术)探究其影响机制的研究.因此,通过归纳微塑料对土壤氮循环影响的不同观点,能更全面地认识微塑料对土壤氮循环存在的影响,可为气候变化条件下土壤微塑料富集对土壤氮素循环过程以及N_(2)O排放规律的影响提供一定的理论基础.

Research on microplastics(MPs)is gaining more attention in the soil environment,but their impact on soil microbiota and related nitrogen processes remains poorly understood.Nitrous oxide(N_(2)O)is one of the important greenhouse gases of the nitrogen cycle in agricultural soil,which mainly originates from microbial-mediated nitrogen(N)transformation processes.Microplastics can influence soil nitrogen transformation,as well as nitrogen-related functional enzymes and genes,and its enrichment may profoundly affect the N_(2)O emissions in soil.However,because of the complexity of the properties of MPs,variations in experimental conditions,and spatial-temporal scales,the results on the effects of MPs on soil N_(2)O emissions,nitrogen content,enzymes activities,and nitrogen functional genes remain inconsistent.Additionally,there is a lack of research conducted at broader experimental scales(e.g.,pot scale),from diverse perspectives(e.g.,denitrification or DNRA),and using advanced techniques(e.g.,stable isotope approaches)to elucidate the underlying mechanisms.Therefore,to comprehend the environmental risk of MPs on soil from multiple perspectives,this review summarized the impact of MPs on soil N cycling from previous published research to provide a knowledge basis and gain holistic insights into the potential impact of soil microplastic enrichment on N_(2)O emission patterns in agricultural soils under climate change conditions.