Dissimilatory nitrate reduction processes in sediments of urban river networks: Spatiotemporal variations and environmental implications

Cheng, Lv; Li, Xiaofei; Lin, Xianbiao; Hou, Lijun; Liu, Min; Li, Ye; Liu, Sai; Hu, Xiaoting

doi:10.1016/j.envpol.2016.05.093

Cited by 69 publications

(50 citation statements)

References 62 publications

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“…DNRA correlated negatively with the concentrations of nitrate in the study area, as the Yangtze Estuary is a hypereutrophic region with excessive nitrate overload [ Deng et al ., ]. Significantly low DNRA rates occurring with high concentrations of nitrate have also been reported in the urban river networks [ Cheng et al ., ]. A remarkable and positive correlation between DNRA rates and the contents of sulfide was determined in this study, which implied that sulfide can induce DNRA by serving as a potential electron donor [ An and Gardner , ; Gardner et al ., ; Lu et al ., ].…”

Section: Discussionmentioning

confidence: 61%

“…The RDA analysis also indicated that nitrite tended to directly participate in the DNRA process instead of involving with DNRA functional gene. Though nitrate can be associated with DNRA [ Laverman et al ., ; Rütting et al ., ], excessive nitrate is discovered to inhibit DNRA activity [ Dong et al ., ; Cheng et al ., ]. DNRA correlated negatively with the concentrations of nitrate in the study area, as the Yangtze Estuary is a hypereutrophic region with excessive nitrate overload [ Deng et al ., ].…”

Section: Discussionmentioning

confidence: 99%

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DNRA in intertidal sediments of the Yangtze Estuary

et al. 2017

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Dissimilatory nitrate reduction to ammonium (DNRA) plays an important role in regulating the fate of reactive nitrogen in estuarine and coastal ecosystems. In this work, intertidal sediments of the Yangtze Estuary were collected in January and August 2015. Potential rates of DNRA and associated functional gene were investigated with nitrogen isotope‐tracing and molecular techniques. The measured DNRA rates ranged from 0.14 to 5.57 μmol 15N kg−1 h−1 in the intertidal sediments. DNRA rates were tightly related to abundance of nrfA gene (p < 0.001), demonstrating that fermentation reaction may be the dominant pathway of DNRA in the study area. Redundancy analysis (RDA) showed a relationship between DNRA and organic matter and NO2−, suggesting that these substrates stimulated the metabolism of DNRA microorganisms. On the other hand, the correlation between abundances of nrfA gene and Fe2+ and sulfide in the RDA analysis implied that oxidation of both Fe2+ and sulfide can enhance fermentative DNRA by providing extra free energy. DNRA converted approximately 2.29 × 105 t of nitrate to ammonia annually in the sampling area of the Yangtze Estuary, and most of the converted ammonium was retained in the estuarine ecosystem. DNRA may further contribute to eutrophication in the Yangtze Estuary and also in the other hypereutrophic estuaries.

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Section: Discussionmentioning

confidence: 61%

Section: Discussionmentioning

confidence: 99%

DNRA in intertidal sediments of the Yangtze Estuary

et al. 2017

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“…As hypothesised, denitrification was responsible for the bulk of in situ nitrate reduction in the Hammer Stream (average 85%), although anammox and DNRA were also quantified, and the calculated contribution of anammox was consistent between the in situ (* 10%) and laboratory, sediment slurry experiments (* 9%). Anammox has only recently been reported in streambed sediments (Cheng et al 2016;Han and Li 2016;Kim et al 2016;Lansdown et al 2016), largely due to the limited attempts to quantify it relative to the focus on denitrification. The similarity of results between in situ experiments and controlled laboratory experiments shows that the conditions in situ are close to optimal for anammox and that the push-pull method works well.…”

Section: Discussionmentioning

confidence: 99%

Enhanced hyporheic exchange flow around woody debris does not increase nitrate reduction in a sandy streambed

et al. 2017

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Anthropogenic nitrogen pollution is a critical problem in freshwaters. Although riverbeds are known to attenuate nitrate, it is not known if large woody debris (LWD) can increase this ecosystem service through enhanced hyporheic exchange and streambed residence time. Over a year, we monitored the surface water and pore water chemistry at 200 points along a * 50 m reach of a lowland sandy stream with three natural LWD structures. We directly injected 15 N-nitrate at 108 locations within the top 1.5 m of the streambed to quantify in situ denitrification, anammox and dissimilatory nitrate reduction to ammonia, which, on average, contributed 85, 10 and 5% of total nitrate reduction, respectively. Total nitrate reducing activity ranged from 0 to 16 lM h -1 and was highest in the top 30 cm of the stream bed. Depth, ambient nitrate and water residence time explained 44% of the observed variation in nitrate reduction; fastest rates were associated with slow flow and shallow depths. In autumn, when the river was in spate, nitrate reduction (in situ and laboratory measures) was enhanced around the LWD compared with non-woody areas, but this was not seen in the spring and summer. Overall, there was no significant effect of LWD on nitrate reduction rates in surrounding streambed sediments, but higher pore water nitrate concentrations and shorter residence times, close to LWD, indicated enhanced delivery of surface water into the streambed under high flow. When hyporheic exchange is too strong, overall nitrate reduction is inhibited due to short flow-paths and associated high oxygen concentrations.

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“…Spatiotemporal variations of (a–f) GNM (gross nitrogen mineralization), DNRA, and NF (nitrogen fixation) rates and (g–l) fractional contribution of each rate to total microbial NH 4 + production rate within the Shanghai river networks. The data of DNRA have been published in the reference (Cheng et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…The amount of dissolved inorganic nitrogen input into Shanghai river networks increased about tenfold from 5.8 × 10 4 t N yr −1 in 1984 to 5.9 × 10 5 t N yr −1 in 2004, which is mainly attributed to fossil fuel combustion, nitrogen fertilizer, and industrial nitrogen use (Gu et al, ). Meanwhile, the river networks receive a substantial amount of inorganic nitrogen mainly in the form of NH 4 + (Cheng et al, ). Excessive NH 4 + input in the rivers has caused eutrophication and decreased water quality during the past several decades (Yu et al, ).…”

Section: Introductionmentioning

confidence: 99%

Ammonium Production and Removal in the Sediments of Shanghai River Networks: Spatiotemporal Variations, Controlling Factors, and Environmental Implications

Lin

Gao

et al. 2017

JGR Biogeosciences

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Ammonium (NH4+) pollution and associated processes causing environmental problems in aquatic ecosystems have attracted much attention. However, the microbial pathways of NH4+ production and removal and associated influencing factors in the sediments of urban rivers remain unclear. In this study, microbial pathways of NH4+ production and removal were quantified to examine the NH4+ balance in the sediments of Shanghai river networks. The results indicated that potential rates of gross nitrogen mineralization, dissimilatory nitrate reduction to ammonium, and nitrogen fixation ranged from 0.25 to 25.83 μg N g−1 d−1, from undetectable to 3.47 μg N g−1 d−1, and from 0.07 to 3.05 μg N g−1 d−1, respectively. The potential rates of gross NH4+ immobilization, anammox, and nitrification, as the NH4+ removal processes, ranged from 0.24 to 26.27 μg N g−1 d−1, from 0.01 to 7.97 μg N g−1 d−1, and from 0 to 9.62 μg N g−1 d−1, respectively. Temperature, dissolved oxygen, NO3−, NH4+, and total organic carbon had great influences on these NH4+ production and removal processes. In addition, the total amounts of NH4+ production and removal through microbial pathways in sediments of Shanghai river networks were estimated at approximately 2.6 × 105 t N yr−1 and 3.9 × 105 t N yr−1, respectively. Thus, the net sink of NH4+ was 1.3 × 105 t N yr−1, which accounts for 22% of total inputs of nitrogen in the river networks. These results indicate that microbial processes of removal in sediments can eliminate significant parts of NH4+ generated from microbial pathways and/or inputs from anthropogenic activities in urban rivers. Overall, these results improve understanding of NH4+ production and removal and associated influencing environmental factors and highlight the environmental importance of these processes in regulating the NH4+ budget in highly urbanized riverine ecosystems.

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Dissimilatory nitrate reduction processes in sediments of urban river networks: Spatiotemporal variations and environmental implications

Cited by 69 publications

References 62 publications

DNRA in intertidal sediments of the Yangtze Estuary

DNRA in intertidal sediments of the Yangtze Estuary

Enhanced hyporheic exchange flow around woody debris does not increase nitrate reduction in a sandy streambed

Ammonium Production and Removal in the Sediments of Shanghai River Networks: Spatiotemporal Variations, Controlling Factors, and Environmental Implications

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