拒马河沉积物N_(2)O产生潜势、途径与微生物群落结构的研究

Potential,pathways,and microbial community of N_(2)O production in sediments of the Juma River

近百年来一氧化二氮(N_(2)O)的排放量急剧增加.但这种强效温室气体在小型河流沉积物中的产生途径以及微生物机制的研究相对匮乏.本研究采集拒马河丰水期与枯水期的岸边带与开阔水域的沉积物(0~10 cm),应用乙炔抑制法、宏基因组测序和Spearman相关性分析等方法,探究拒马河沉积物N_(2)O的产生潜势、主导过程、微生物机制及影响因素.结果表明,拒马河沉积物N_(2)O产生潜势为(1.48±0.38)μg·kg^(-1)·h^(-1).氨氧化过程是拒马河沉积物N_(2)O产生的主导过程,其N_(2)O产生潜势为(0.97±0.31)μg·kg^(-1)·h^(-1),是反硝化过程N_(2)O产生潜势的1.88倍.拒马河沉积物产N_(2)O相关微生物的多样性呈现出明显的季节性变化,丰水期的产N_(2)O相关微生物的Alpha多样性显著高于枯水期(p<0.05).硝化螺旋菌属(Nitrospira)与黄色类固醇杆菌属(Steroidobacter)是拒马河沉积物中氨氧化微生物与反硝化微生物的优势菌属.Spearman相关性和冗余分析表明,铵态氮(NH_(4)^(+)-N)的浓度与氨氧化过程产生N_(2)O潜势呈显著正相关(r=0.53,p<0.05),亚硝化螺菌属(Nitrosospira)与黄色类固醇杆菌属(Steroidobacter)是参与拒马河沉积物N_(2)O产生的关键菌属(r=0.53,p<0.05;r=0.47,p<0.05).本研究揭示了拒马河沉积物N_(2)O产生潜势、主导过程以及微生物群落结构,对河流生态系统中长期被忽略的氨氧化过程产生N_(2)O的作用进行补充,为治理河流氮污染提供新思路.

Nitrous oxide(N_(2)O)emissions have witnessed a substantial increase in recent decades;however,there is a dearth of studies investigating the production pathway and microbial mechanism underlying this potent greenhouse gas in small river sediments.Our study employed the acetylene inhibition method,metagenomic sequencing,and Spearman correlation analysis to elucidate the potential for N_(2)O production,dominant processes,microbial mechanisms,and influencing factors in sediments from both the riparian zone and open water zone of the Juma River during both rainy and dry seasons.The findings revealed that the N_(2)O production potential in the sediments of the Juma River was estimated to be(1.48±0.38)μg·kg^(-1)·h^(-1).The ammonia oxidation process was the main process generating N_(2)O production with a potential rate of(0.97±0.31)μg·kg^(-1)·h^(-1),which was 1.88 times higher than that of denitrification process.The diversity of N_(2)O producing microorganisms exhibited noticeable seasonal variations within Juma River sediments,with significantly higher Alpha diversity observed during summer compared to winter(p<0.05).The dominant genera among ammonia oxidizing and denitrifying microorganisms in Juma River sediments were identified as Nitrospira and Steroidobacter,respectively.Both Spearman correlation and redundancy analyses revealed a significant positive correlation(r=0.53,p<0.05)between the concentration of ammonium nitrogen(NH_(4)^(+)-N)and the N_(2)O production potential of the ammonia oxidation process.Nitrosospira and Steroidobacter are key genera involved in the production of N_(2)O in the sediments of Juma River(r=0.53,p<0.05;r=0.47,p<0.05).This study provides insights into the potential for N_(2)O production,dominant processes,and microbial community composition in Juma River sediments,thereby enhancing our understanding of the previously overlooked contribution of ammonia oxidation to N_(2)O production in river ecosystems and offering new perspectives on mitigating nitrogen pollution.