N₂O Emissions And Microbial Community Structure Of WLFZ In The Three Gorges Reservoir Area

Nitrous oxide?N2O?is an important greenhouse gases. with a great potential to temperature increase, the increase in soil N₂O emissions is one of the important reasons for the rising atmospheric N₂O concentrations in recent decades. Riparian zone is hydro scheduling of the Three Gorges reservoir?TGR? caused by the reservoir WLFZ?water level fluctuating zone? counter seasonal variation. The study of soil N₂O emission characteristics can provide theoretical support for the influence of the unique periodic wetting and drying process on N₂O emission.The changes of N₂O emission under the conditions of dry, flooding, drought and waterlogged condition were studied. The results showed that the fall dry cultivation under N₂O emissions two inflection point, the first time inflection point appeared in WFPS is 90% 110%, at this time, soil N₂O emission flux reached minimum; the second inflection point appeared in the WFPS is 50% 60%, the culture group of soil N₂O emission flux reached the highest. Under water flooding, 1⁶d soil is N₂O "sink", and then gradually transformed into N₂O "source". Under drought and waterlogged incubation,but N₂O emissions were lower than flooding process under the same temperature N₂O fluxes. Fall dry cultivation under N₂O emissions flux peak 130.6 ug·N·m-2·h-1, respectively is waterlogged incubation and drought and flooding cultivation soil N₂O emissions to peak and 1.9 times and 4.5 times and fall dry cultivation under N₂O emission fluctuations far higher than the other two groups.The method of acetylene and oxygen inhibition was used to study the WFPS emission from soil N₂O under 20%¹20%. The results showed that the contribution of N₂O to the total emission of N₂O in soil decreased with the increase of WFPS. When WFPS is greater than 100%, the contribution of N₂O to the total N₂O emission from soil is negative. The contribution of N₂O to the total emission of N₂O in the soil was increased with the increase of WFPS. When WFPS is less than 40%, the contribution rate of AOB denitrification and other pathways of N₂O to soil N₂O emission is 27.0%²9.2%.while WFPS in 20%¹20%, the contribution of soil nitrification and denitrification in the amount of N₂O generated in the soil N₂O total emission rate was 70.8%⁸8.4%. The pathways of nitrification and denitrification pathways are the major contributors to the N₂O emission from the soil N₂O emission.The N₂O emission characteristics of the riparian zone was studied by using undisturbed soil column culture method. The N₂O emission from different flooded area showed a significant change, Its N₂O emissions from flooded area> seasonally flooded field> non flooded area, and the N₂O emissions of the soil was all at the end of July. N₂O emission of different flooded area in May to September was?20.6±2.0?^69.7±5.7 ug·N·m-2·h-1,which showed the release of N₂O,showing Fluctuating Zone in different areas were N₂O "source".Using the Illumina Hiseq high-throughput sequencing different flooding degree of soil microbial community structure and dominant bacteria change characteristics. The dminant species in non-flooded periods were almost the same, Dominant species had great changes, and non-flooded had a great influence on the relative abundance of the species in the soil. The soil in different area of WLFZ had ammonium oxidizing bacteria and denitrification bacteria, and the relative abundance was 1.3%⁴.9% and 1.9%¹0.6% respectively. There was a positive correlation of soil N₂O emission and ammonia oxidizing microorganisms and denitrification microorganisms in different regions.