Distribution And Activity Of Nitrite-cycle Bacteria In Wetland System

As an important part of natural ecosystem, wetland is the hotspot of biogeochemical cycle of nitrogen. In this paper, we chose vertical soil samples of Baiyangdian natural wetland, sediment samples of open water and shore zone in Shijiuyang constructed wetland of Jiaxing as research objects, using molecular biology techniques including quantitative PCR and PCR cloning library, associated with 15 N isotope tracer technique, to study the distribution and activity of anammox bacteria in wetland system. Meanwhile, some pivotal microorganisms of nitrogen cycle associated with anammox were quantitatively analyzed.The study result of the Baiyangdian vertical soil samples indicated that anammox bacterial abundance increased significantly near groundwater level, the interfaces of deep soils and groundwater were the high abundance regions of anammox bacteria, where anammox activity can be detected, but anammox activity had no pure positive correlation with anammox bacterial abundance.Anammox bacteria had wide existence in sediments of Shijiuyang constructed wetland, whose abundance ranged from 4.59×105 to 7.78×107 copies g-1 dry soil, and anammox bacterial abundance was higher in shore zone sediments than that in open water sediments. The result of 15 N isotope tracer experiment indicated that anammox bacterial activity and its contribution to nitrogen lost were significantly higher in shore zone sediments than that in open water sediments, which was consistent with anammox bacterial distribution. The analysis of anammox bacterial hzsB gene cloning library showed that the majority of anammox bacteria in Shijiuyang wetland system belonged to ―Brocadia‖, the minority belonged to ―Jettenia‖. The quantitative result of AOA and AOB indicated that ammonia oxidation process in Shijiuyang wetland may be dominated by AOB rather than AOA. Besides, both all bacterial abundance and denitrification bacterial abundance were higher in shore zone sediments than that in open water sediments, which further demonstrated that wetland shore zone had higher biogeochemical activity.The above study result provided reference for the removal of nitrogen in surface water and groundwater. It had great significance to spread the wetland treatment of nitrogen removal in ammonia nitrogen micro-polluted raw water to southern cities in China with water shortage of water quality and hydrographic net as water source, even the usage of constructed wetland in ecological nitrogen removal project in sewage plant.