沣河水系脱氮微生物群落结构研究

河流水体氮素的超负荷不仅破坏了水体生态环境,也严重威胁着人类的生存和发展.水体中有机氮、无机氮（氨氮、亚硝氮、硝氮）和分子氮之间的转化（氮循环）有赖于水体中大量的氮循环微生物（固氮细菌、硝化细菌和反硝化细菌）,然而这些氮循环微生物的生长繁殖也受到包括氮素的形态和浓度在内的多种环境因子的影响,这些因素也通过影响氮循环微生物的生长繁殖进而使得水体中氮素的转化速率发生变化,对水体氮污染的防治有不可忽视的作用.本研究通过在沣河设置不同的研究断面,采集水体样品,进行水质分析,并通过现代分子生物学技术（PCR-DGGE）方法对研究断面水体中氮循环微生物（固氮细菌、硝化细菌和反硝化细菌）的群落结构进行分析.再通过统计学软件对所得分子生物学信息与水质环境因子的相关性进行统计学分析,发现沣河水体中氮循环微生物群落结构受到多种环境因子共同影响,且在枯水期和丰水期表现出不同的特征.在丰水期沣河水体中,硝化细菌群落在中游表现出较高的多样性和丰富性,这与沣河中上游农业COD（化学需氧量）、BOD（生化需氧量）氨氮及有机氮污染物排放量较大,沣河水体DO（溶解氧）高有关.水体中的氨氮、亚硝氮、温度的增加是促进水体中硝化细菌的均匀性和丰富度的增高的主要因子,而pH 值的升高,使得水体中硝化细菌的均匀性和丰富度降低.反硝化微生物在中游和下游的多样性和丰富度较高,与有机物及硝酸盐含量相关.水体中的BOD、COD、TP（总磷）、硝氮的增加是促进水体中反硝化细菌的均匀性和丰富度的增高主要相关因子,而DO 的增多则会对部分反硝化细菌产生不利影响,使得水体中反硝化细菌的均匀性和丰富度降低.本研究结果为沣河以及其他河流的污染控制以及基于微生物的生态修复提供了科?

Study on the microorganisms of nitrogen cycle in Fenghe river

Nitrogen （N） is among the paramount interests to biogeochemistry and life on earth. But pollution of N in river water willmake a threat to the ecological environment and human life.The transformation among organic nitrogen, inorganic nitrogen（ammonia, nitrite, nitrate） and molecular nitrogen（N2） in river water, called nitrogen cycling, depends on the nitrogen cyclemicroorganisms （nitrogen-fixing bacteria, nitrifying bacteria and denitrifying bacteria）. And these microorganisms and their activityof the nitrogen cycling are affected by a variety of environmental factors including the form and concentration of nitrogen, thesefactors affect the growth of microorganisms thus change the rate of transformation of nitrogen in water, which make a significantcontribution to prevention of nitrogen pollution and removal of nitrogen pollutants. And thus a research of nitrogen cycle microbialand the related environmental factors is of great importance to removal of nitrogen pollutants in river water.Based on PCR-DGGEtechnology, water sampling points along the Feng River were set to study on the water quality and community of microorganismsrelated with nitrogen cycle. Then the related statistical softwares were used to analyze the relationship among the water quality andcommunity of microorganisms related.In this study, during wet season, nitrifying bacteria community structure in the middle reachesis relatively rich in water, resulted from the agricultural COD, BOD, ammonia nitrogen, organic nitrogen emissions and high riverwater DO level. The increasing of BOD, ammonia nitrogen, nitrate nitrogen, T, TP promoted to the uniformity, richness of nitrifyingbacteria in water, while the rising of pH reduced the uniformity and the abundance of nitrifying bacteria in water. Denitrifyingbacteria community structure in the midstream and downstream is relatively rich in water, associated with organic matter and nitratecontent. The increasing of BOD ,COD, TP, nitrate nitrogen was the main related factor of the uniformity,