Nitrogen transformation pathway and potentials illuminated by nitrogen-cycling gene abundances of urban rivers under high nitrogen contents
Understanding the nitrogen cycle driven by microbes in sediments of urban river under high nitrogen contents could provide scientific basis to water and sediment nitrogen controlling.Analysis of nitrogen compounds in the water and sediment samples from four cities situated at the Yangtze River Delta showed that,the total nitrogen(TN)in the overlying water and sediment in rivers of three downtown(SZ,WX,NJ)reached to 7.04 mg·L-1 and 2372.34 mg·kg-1,which were relatively higher than rivers of the suburb(YX).The abundances of nitrogen involving genes including amoA,hzsB,nirS,nirK,nrfA,norB,nosZ and hzo gene were determined by real time quantitative PCR.The AOA dominated the ammonia oxidizing microbes.The nirK gene were the most abundant among genes related to nitrite reduction(nirS,nirK,and nrfA).The other three gene abundances from different samples showed no significant difference.The(AOA-amoA+AOB-amoA)/(nirS+nirK+nrfA)ratio were lower than 0.09,which implied that nitrification was the limiting step.The(nirS+nirK)/nrfA ratio were ranged from 2.52 to 3.94,indicating that DNRA was also an important pathway of nitrite reduction.In addition,higher norB/nosZ(6.23~32.84)also suggest high potential of N2O emission.The coupled nitrification-denitrification dominate the nitrogen-cycling pathway.Nitrification was the limiting step of nitrogen cycling.Higher nitrogen contents could stimulate the growth of ammonium oxidizing archaeon,and consequently enhance the NH4+oxidizing potential.However,the increase of NH4+oxidizing potential could not neutralize the nitrogen increase.
nitrogen cycle functional gene nitrogen loading urban river sediment
Yaping Zhang Xiaohong Ruan Rongfu Li Yuehui Luo Wenli Shi
Key Laboratory of surficial Geochemistry,Ministry of Education,Nanjing,210023,China;School of Earth Sciences and Engineering,Nanjing University,Nanjing,210023,China
国际会议
The 11th International Symposium on Geochemistry of the Earths Surface(GES-11)(第十一届地球表层地球化学国际研讨会)
贵阳
英文
1-4
2017-06-11（万方平台首次上网日期，不代表论文的发表时间）