Abundance And Diversity Of Ammonia-oxidizing Archaea In Dasha River

With the rapid development of the urbanization, the pollution of urban rivers isgetting serious. As one of the major pollutants in urban rivers, whether ammonia can beeffectively removed is an important index of water standard quality. Ammonia oxidationis the key step of biological nitrogen removal. For a long time, ammonia oxidizingbacteria(AOB) is regarded as the main microorganism involved in this process.However, a kind of archaeal, which was found in recently studies, is also capable ofoxidizing ammonia and is called ammonia oxidizing archaea(AOA). Recent studiesfocused mainly on the oceans, soil, and sewage treatment plants, the study oflight-polluted urban rivers is very lacking. To have a better understanding of thepattern of population distribution of AOA in light-polluted rivers, revealing itsregulation of water quality factors to be used in the light-polluted urban rivers, thisobjective of this study is to give a systematic research on the AOA’s populationdistribution and community structure of a typical light-polluted urban river-ShenZhenDasha river.This research conducted the population of AOA and AOB in Dasha river withquantitative PCR and FISH techniques. In the selected five typical aquatic environments,the number of AOA was significantly higher than AOB, and particularly at the Dashariver Park section, the ratio of AOA to AOB reaches a maximum value. At the sametime, the number of AOA is higher than AOB in this section. Using statistical softwareto analysis water quality factors and the number of AOA for each typical waterenvironments, It was found that, the mainly factors affecting the number of AOA inDasha River is ammonia nitrogen, total nitrogen and total organic carbon.With the use of clone library technology to study the community structure of AOAin five typical aquatic environments, AOA community structure changed significantlyalong the river. The main communities of AOA in different sampling points weredifferent, but they were all highly similar with known freshwater sediments. The mainimpact factors of AOA community structure in the ecosystem were dissolved oxygenconcentration, pH, temperature and nitrate concentrations.After analyzingthe preliminaryresults of this study, and concluding the optimalculture conditions of other researchers,a number of environmental factors affecting thegrowth of AOA were selected to gain a best growing environment for AOA.Orthogonalexperimental was conducted to study the physical and chemical factors affecting to thenumber of AOA changes, and optimize the most suitable conditionfor the growth ofAOA in the Dasha river.Then the expansion and stable operation is conducted under this condition, and the results showed that, the growth AOA is better than any otherconditions,and ammonia removal in the water is going well.