Effects of plantingPhragmites australison nitrogen removal, microbial nitrogen cycling, and abundance of ammonia-oxidizing and denitrifying microorganisms in sediments

Abstract Urban rivers are considered as a hot spot of microbial nitrogen cycling due to extensive N loading. However, microbial nitrogen transformation dynamics in urban rivers with different dissolved oxygen (DO) conditions are still unclear. This study investigated the effects of DO concentration changes (anaerobic to aerobic) in overlying water on nitrogen-cycling gene abundance in incubation conditions using sediment from a typical urban river in the Yangtze River Delta. Quantitative polymerase chain reaction (qPCR) results revealed that the abundances of the nitrification gene amoA, denitrification gene nirS/K, norB, nosZ, and anammox gene hzo increased by one to two orders of magnitude from anaerobic to aerobic conditions. Ammonia-oxidizing archaea (AOA) predominated the ammonium oxidation microbial populations, about tenfold more than the ammonia-oxidizing bacteria (AOB) populations. Significant correlations were found among the abundances of AOA-amoA, AOB-amoA, nirS, nirK, and hzo genes, implying a close coupling of aerobic ammonium oxidation (AAO), denitrification, and anammox processes at the molecular level. Moreover, the nitrogen transformation rates were calculated using a box model linking the measured dissolved inorganic nitrogen species. The contribution of anammox to N2 production was 85% under saturated treatment, and the AAO rate was significantly positive correlated to the anammox rate. Our results suggested that coupled AAO and anammox might be the dominant pathway for reactive nitrogen removal in urban rivers with elevated DO levels.

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The Diversity of Nitrogen-Cycling Microbial Genes in a Waste Stabilization Pond Reveals Changes over Space and Time that Is Uncoupled to Changing Nitrogen Chemistry

Microbial Ecology ◽

10.1007/s00248-020-01639-x ◽

2020 ◽

Author(s):

A. Rose ◽

A. Padovan ◽

K. Christian ◽

J. van de Kamp ◽

M. Kaestli ◽

...

Keyword(s):

Nitrogen Cycling ◽

Functional Groups ◽

Nitrogen Removal ◽

Ammonia Oxidation ◽

Gene Array ◽

N Cycling ◽

Nitrogen Levels ◽

Space And Time ◽

Waste Stabilization ◽

Wastewater Samples

Abstract Nitrogen removal is an important process for wastewater ponds prior to effluent release. Bacteria and archaea can drive nitrogen removal if they possess the genes required to metabolize nitrogen. In the tropical savanna of northern Australia, we identified the previously unresolved microbial communities responsible for nitrogen cycling in a multi-pond wastewater stabilization system by measuring genomic DNA and cDNA for the following: nifH (nitrogen fixation); nosZ (denitrification); hzsA (anammox); archaeal AamoA and bacterial BamoA (ammonia oxidation); nxrB (nitrite oxidation); and nrfA (dissimilatory NO3 reduction to NH3). By collecting 160 DNA and 40 cDNA wastewater samples and measuring nitrogen (N)-cycling genes using a functional gene array, we found that genes from all steps of the N cycle were present and, except for nxrB, were also expressed. As expected, N-cycling communities showed daily, seasonal, and yearly shifts. However, contrary to our prediction, probes from most functional groups, excluding nosZ and AamoA, were different between ponds. Further, different genes that perform the same N-cycling role sometimes had different trends over space and time, resulting in only weak correlations between the different functional communities. Although N-cycling communities were correlated with wastewater nitrogen levels and physico-chemistry, the relationship was not strong enough to reliably predict the presence or diversity of N-cycling microbes. The complex and dynamic response of these genes to other functional groups and the changing physico-chemical environment provides insight into why altering wastewater pond conditions can result an abundance of some gene variants while others are lost.

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Biodiversity breakpoints along stress gradients in estuaries and associated shifts in ecosystem interactions

Scientific Reports ◽

10.1038/s41598-019-54192-0 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Emily J. Douglas ◽

Andrew M. Lohrer ◽

Conrad A. Pilditch

Keyword(s):

Nitrogen Cycling ◽

Environmental Gradients ◽

Interaction Network ◽

Coastal Sediments ◽

Ecosystem Functions ◽

Ecological Interactions ◽

Fine Sediments ◽

Microbial Nitrogen ◽

Ecosystem Interactions ◽

Biodiversity Effects

AbstractDenitrification in coastal sediments can provide resilience to eutrophication in estuarine ecosystems, but this key ecosystem function is impacted directly and indirectly by increasing stressors. The erosion and loading of fine sediments from land, resulting in sedimentation and elevated sediment muddiness, presents a significant threat to coastal ecosystems worldwide. Impacts on biodiversity with increasing sediment mud content are relatively well understood, but corresponding impacts on denitrification are uncharacterised. Soft sediment ecosystems have a network of interrelated biotic and abiotic ecosystem components that contribute to microbial nitrogen cycling, but these components (especially biodiversity measures) and their relationships with ecosystem functions are sensitive to stress. With a large dataset spanning broad environmental gradients this study uses interaction network analysis to present a mechanistic view of the ecological interactions that contribute to microbial nitrogen cycling, showing significant changes above and below a stressor (mud) threshold. Our models demonstrate that positive biodiversity effects become more critical with a higher level of sedimentation stress, and show that effective ecosystem management for resilience requires different action under different scenarios.

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Bend-induced sediment redistribution regulates deterministic processes and stimulates microbial nitrogen removal in coarse sediment regions of river

Water Research ◽

10.1016/j.watres.2019.115315 ◽

2020 ◽

Vol 170 ◽

pp. 115315 ◽

Cited By ~ 1

Author(s):

Wenlong Zhang ◽

Haolan Wang ◽

Yi Li ◽

Li Lin ◽

Cizhang Hui ◽

...

Keyword(s):

Nitrogen Removal ◽

Coarse Sediment ◽

Microbial Nitrogen ◽

Sediment Redistribution ◽

Deterministic Processes

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Microbial nitrogen removal pathways in integrated vertical-flow constructed wetland systems

Bioresource Technology ◽

10.1016/j.biortech.2016.01.106 ◽

2016 ◽

Vol 207 ◽

pp. 339-345 ◽

Cited By ~ 66

Author(s):

Yun Hu ◽

Feng He ◽

Lin Ma ◽

Yi Zhang ◽

Zhenbin Wu

Keyword(s):

Nitrogen Removal ◽

Constructed Wetland ◽

Vertical Flow ◽

Microbial Nitrogen ◽

Vertical Flow Constructed Wetland

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Novel microbial nitrogen removal processes

Biotechnology Advances ◽

10.1016/j.biotechadv.2004.04.003 ◽

2004 ◽

Vol 22 (7) ◽

pp. 519-532 ◽

Cited By ~ 187

Author(s):

Than Khin ◽

Ajit P. Annachhatre

Keyword(s):

Nitrogen Removal ◽

Microbial Nitrogen ◽

Removal Processes

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Microbial nitrogen cycling on the Greenland Ice Sheet

Biogeosciences Discussions ◽

10.5194/bgd-8-10423-2011 ◽

2011 ◽

Vol 8 (5) ◽

pp. 10423-10457 ◽

Cited By ~ 2

Author(s):

J. Telling ◽

M. Stibal ◽

A. M. Anesio ◽

M. Tranter ◽

I. Nias ◽

...

Keyword(s):

Nitrogen Fixation ◽

Nitrogen Cycling ◽

Microbial Growth ◽

Inorganic Nitrogen ◽

Ice Sheet ◽

Greenland Ice Sheet ◽

Available Nitrogen ◽

Microbial Nitrogen ◽

Nitrogen Demand

Abstract. Microbial nitrogen cycling was investigated along a 79 km transect into the Greenland Ice Sheet (GrIS) in early August 2010. The depletion of dissolved nitrate and production of ammonium (relative to icemelt) in cryoconite holes within 7.5 km of the ice sheet margin suggested microbial uptake and ammonification respectively. Nitrogen fixation (<4.2 μmoles C2H4 m−2 day−1 to 16.3 μmoles C2H4 m−2 day−1) was active in some cryoconite holes at sites up to 5.7 km from the ice sheet margin, with nitrogen fixation inversely correlated to concentrations of inorganic nitrogen. There may be the potential for the zone of nitrogen fixation to progressively extend further into the interior of the GrIS as the melt season progresses as reserves of available nitrogen are depleted. Estimated annual inputs of nitrogen from nitrogen fixation along the transect were at least two orders of magnitude lower than inputs from precipitation, with the exception of a 100 m long marginal debris-rich zone where nitrogen fixation could potentially equal or exceed that of precipitation. The average estimated contribution of nitrogen fixation to the nitrogen demand of net microbial growth at sites along the transect ranged from 0% to 17.5%.

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