长江口及邻近海域沉积物中硝化与反硝化细菌分布特征研究

本研究应用DAPI荧光染色法和荧光定量PCR技术对长江口及邻近海域沉积物中的总细菌、好氧氨氧化细菌和反硝化细菌生物量的分布特征进行分析。结果表明，对于垂直分布，同一深度的反硝化细菌生物量明显高于好氧氨氧化细菌生物量，但二者的垂直分布趋势相似。沉积物的强烈混合有利于好氧氨氧化细菌和反硝化细菌的生存。柱状沉积物的深度是影响总细菌、好氧氨氧化细菌和反硝化细菌生物量垂直分布的最重要因素，且深度增加对好氧氨氧化细菌的影响大于对总细菌和反硝化细菌的影响。对于水平分布，总细菌生物量由近岸到远岸逐渐降低，亚硝酸盐浓度显著影响其水平分布。好氧氨氧化细菌和反硝化细菌生物量分别在长江口外和舟山群岛以南海域存在高值区，且溶解氧浓度和总氮含量是影响二者生物量水平分布的重要因素。本研究可为更加深入地认识细菌在河口及近岸海域氮循环过程中的作用提供依据。

Distribution characteristics of nitrifiers and denitrifiers in sediments from Changjiang Estuary and adjacent sea area

The biomass distribution characteristics of total bacteria, aerobic ammonium-oxidizing and denitrifying bacteria in sediments from Changjiang Estuary and adjacent sea area were analyzed using DAPI staining and fluorescent quantitative PCR technology. For the vertical distribution, denitrifying bacteria (DB) biomass was much higher than that of aerobic ammonium-oxidizing bacteria (AOB) at the same depth, but there were similar trends between their vertical biomass. The intense mixing of sediments was suitable for AOB coexisting with DB. Sediment depth was the most significant influencing factor to the vertical biomass profiles of total bacteria, AOB and DB. The increasing depth affected AOB more easily than total bacteria and DB. For the horizontal distribution, total bacterial biomass gradually decreased from inshore to offshore, which was significantly impacted by the nitrite concentration. There were high biomass areas of AOB and DB in the sea area off Changjiang Estuary and the south sea area of Zhoushan Archipelago, respectively, and dissolved oxygen concentration and total nitrogen content were important influencing factors to their horizontal distributions. This study provided support for thoroughly understanding the role of bacteria in nitrogen cycles in estuarine and coastal sea area.