Community structures of ammonia-oxidizing and their role in the nitrogen circle in surface sediments of shallow lakes with different pollutant sources

The purpose of this work was to investigate the effects of fenced aquaculture, livestock and poultry rising, agricultural non-point source pollution, and submerged plant enrichment on the diversity and community composition of ammonia-oxidizing microorganisms in the sediments of shallow lakes. Ammonia-oxidizing archaea (AOA) has been found in surface sediments of shallow lakes in the Lixiahe region, Jiangsu Province, China, which provided an example of the global extent and geographical distribution of AOA habitats. The distribution of AOA in these shallow lakes was examined in this study. Rich organic matter promoted the growth of AOA. There was a small difference of destination sequences between Group 1.1b and Group 1.1a at the sediments of Lake Dazong sample point in Lake Dazong, in which the AOA came mainly from terrigenous environment and lake water and sediments of Lake Dazong. The factories and fisheries around the shores of Lake Desheng and the livestock-raising area in the upper reaches of Lake Jiulongkou influence the community features of surface sediments. The long-term fenced breeding has increased the injection of artificial pollution source, reduced the ratio of nitrogen isotope, and resulted in the reduction of AOB abundance and diversity at this sampling point. The relatively high diversity and abundance of AOA or AOB accelerate the transformation of ammonia nitrogen to nitrate nitrogen, reduce the ammonia nitrogen in surface sediments and increase the nitrate nitrogen in the sediments and overlying water.