title: Seasonal variation and controlling factors of anaerobic ammonium oxidation in freshwater river sediments in the Taihu Lake region of China.
abstract: Anaerobic ammonium oxidation (anammox) has been recently recognized as an important pathway for the removal of fixed nitrogen (N) from aquatic systems. However, the functions of anammox in freshwater river systems remain uncertain. In this study, we evaluated the occurrence of anammox activity in two rivers in the Taihu Lake region in China during a seasonal survey. Homogenized sediments were incubated with (15)N-labeled NO3(-) and NH4(+) amendments to determine the potential importance of the anammox process relative to canonical denitrification. Production of (29)N2 and (30)N2 in slurries was determined using membrane inlet mass spectrometry. Potential anammox rates in the two river sediments ranged from 0.11±0.07 to 6.79±1.28 μmol N m(-2) h(-1) and the remove of N by anammox accounted for 0.8±0.00% to 10.7±0.03% of total N2 production. Potential anammox rates varied spatially and temporally in the two rivers, with the highest and lowest mean anammox rates appearing during summer and early autumn and during winter, respectively. The variation of the percentage of anammox to total N2 production displayed the same trend with potential anammox rates. Water temperature and NO3(-) content in sediments were the main factors affecting anammox activity. Anammox bacteria were detected in sediment samples using barcode pyrosequencing. The 16S rRNA anammox gene sequences in the river sediments were affiliated with Candidatus Kuenenia, Candidatus Jettenia, and Candidatus Scalindua, among which C. Kuenenia dominated the anammox bacterial communities. Our results confirmed the presence of anammox bacteria but their role is relatively small in removing fixed N from freshwater river systems.
authors: State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors: Yongqiang
authors: Y
authors: Zhao
authors: Yongqiu
authors: Y
authors: Xia
authors: Todd M
authors: TM
authors: Kana
authors: Yucheng
authors: Y
authors: Wu
authors: Xiaobo
authors: X
authors: Li
authors: Xiaoyuan
authors: X
authors: Yan
mesh_terms: D064751:Ammonium Compounds / Q000032:analysis* / Q000378:metabolism; D000693:Anaerobiosis; D001419:Bacteria / Q000378:metabolism; D002681:China; D019015:Geologic Sediments / Q000737:chemistry*; D060106:Lakes / Q000737:chemistry* / Q000382:microbiology; D010084:Oxidation-Reduction; D045483:Rivers / Q000737:chemistry / Q000382:microbiology; D012621:Seasons; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000378:metabolism; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data
chemical_list: D064751:Ammonium Compounds; D014874:Water Pollutants, Chemical
keywords: 16S rRNA; Anammox; Denitrification; Isotope-pairing; Membrane inlet mass spectrometry; River systems