东湖氮循环细菌分布及其作用

用最大可能数法测定东湖不同水期水体及底泥中亚硝化、硝化、反硝化和氨化细菌的分布,并分析其作用.结果表明,水体中亚硝化菌的最大可能数丰水期最高,平水期居中,枯水期最小;硝化菌丰水期小于其他2期,而反硝化、氮化细菌均是平水期最高、丰水期次之,枯水期最小.底泥中亚硝化菌n(MPN)丰水期高于另2期,硝化菌枯水期最高,而反硝化菌枯水期低于其它2水期,氮化细菌无差别.对比水相、泥相发现,亚硝化菌丰水期、枯水期泥相均大于水相(p<0.01),平水期无差别.硝化菌在平水、丰水2期的水相中占优势,枯水期差别不大反硝化菌n(MPN)仅在平水期泥相占优势,氨化细菌2相中无差别.氮循环细菌的分布及微环境的差异,促进了有机氮的分解、氮态氮的硝化和挥发及硝酸盐的反硝化作用.研究还发现,水体、底泥中反硝化细菌和氨化细菌1gn(MPN)]与其气体截流量之间有显著相关(p<0.001),且不同水期产气量不同(p<0.05),表明氨化作用和反硝化作用随水期变化较大.氨化作用可将有机氮转化为铵和氨,促进水体及底泥中的氮以气态氨的形式挥发;反硝化作用将硝酸盐转化为N₂O、N₂,促进氮素释放.

Distribution and Role of Denitrifying, Nitrifying, Nitrosation and Ammonifying Bacteria in East Lake

The most probable number (MPN) method was employed to determine the distribution and role of four nitrogen cycle bacteria, including ammonifying bacteria, denitrifying bacteria, nitrosobacteria and nitrobacteria, in East Lake, Wuhan. The results showed that the n(MPN ) of nitrosobacteria in water was most in rainy season and least in dry season, while the number in common season between them. The n(MPN) of water nitrobacteria in rainy season was less than in the other two seasons. The n(MPN) of water ammonifying and denitrifying bacteria were most in common season, least in dry season. The n(MPN) of nitrosobacteria in sediment in rainy season was more than that in other seasons. The n(MPN) of sediment nitrobacteria was most in dry season while denitrifying bacteria was more in dry season than in other seasons. The n(MPN) of ammonifying bacteria had no difference among three seasons. Compared with water phase, the n(MPN) of nitrosobacteria in sediment phase was more in rainy and dry season (p<0.01),while nitrobacteria's number was prevailing in water phase during common and rainy season while denitrifying bacteria's was prevailing only in common season(p<0.01) .The ammonifying bacteria had no difference in water and sediment. The results demonstrated that the difference in distribution of four nitrogen cycle bacteria in two phase and three season played a significant role in nitrogen removal, which promoted ammoniation, nitrification ,nitrosification and denitrification in lake. The study also found that the lgn(MPN)] of denitrifying and ammonifying bacteria in water and sediment had significant correlation with the catching gas volume(p<0.001).Furthermore, different season had different gas volume (p<0.01), which showed that ammoniation and denitrification could convert organic nitrogen and nitrate into gas nitrogen(NH₃,N₂O ,N₂) and also varied greatly with different season.