scholarly journals Changes in the nitrogen biogeochemical cycle in sediments of an urban river under different dissolved oxygen levels

2018 ◽  
Vol 19 (4) ◽  
pp. 1271-1278 ◽  
Author(s):  
Yaping Zhang ◽  
Xiaohong Ruan ◽  
Wenli Shi
Keyword(s):  
Dissolved Oxygen ◽  
Nitrogen Cycling ◽  
Quantitative Polymerase Chain Reaction ◽  
Nitrogen Transformation ◽  
Urban River ◽  
Ammonia Oxidizing Bacteria ◽  
Urban Rivers ◽  
Ammonium Oxidation ◽  
Microbial Nitrogen ◽  
Concentration Changes

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.

scholarly journals Optimization of water flushing in lowland urban river in Jiaxing, Zhejiang using dissolved oxygen as the indicator

2018 ◽  
Vol 246 ◽  
pp. 02048
Author(s):  
Peiying Tan ◽  
David Z. Zhu ◽  
Yiping Zhang ◽  
Yongchao Zhou
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Water Temperature ◽  
Urban River ◽  
Saturation Level ◽  
Evaluation Index ◽  
Urban Rivers ◽  
Time Intervals ◽  
Exponential Relationship ◽  
Do Concentration

River flushing has been considered as an effective tool for improving water quality in heavily polluted urban rivers. Dissolved oxygen (DO) as the evaluation index of water quality varied with time during and after water flushing. The time intervals between the flushing should be optimized such that the DO concentration remains above 2mg/L in the river. The duration between the flushing was found to be mainly correlated to the water temperature and the saturation level of dissolved oxygen. For the study river, when the temperature was below 15 ℃, there was an exponential relationship between the duration and saturation level of DO. For instance, the estimated duration was 157 hours or about 7 days for the subsequent flushing when the saturation level of DO was 90%. This duration was no more than 2 days when the temperature was above 15 ℃.

scholarly journals The Dynamic Response of Nitrogen Transformation to the Dissolved Oxygen Variations in the Simulated Biofilm Reactor

2021 ◽  
Vol 18 (7) ◽  
pp. 3633
Author(s):  
Qianqian Lu ◽  
Nannan Zhang ◽  
Chen Chen ◽  
Miao Zhang ◽  
Dehua Zhao ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
Copy Number ◽  
Stable State ◽  
Quantitative Relationship ◽  
Nitrogen Transformation ◽  
Biofilm Reactor ◽  
Short Term ◽  
Nirs Gene ◽  
Biofilm Reactors ◽  
Recovery Times

Lab-scale simulated biofilm reactors, including aerated reactors disturbed by short-term aeration interruption (AE-D) and non-aerated reactors disturbed by short-term aeration (AN-D), were established to study the stable-state (SS) formation and recovery after disturbance for nitrogen transformation in terms of dissolved oxygen (DO), removal efficiency (RE) of NH4+-N and NO3−-N and activity of key nitrogen-cycle functional genes amoA and nirS (RNA level abundance, per ball). SS formation and recovery of DO were completed in 0.56–7.75 h after transition between aeration (Ae) and aeration stop (As). In terms of pollutant REs, new temporary SS formation required 30.7–52.3 h after Ae and As interruptions, and seven-day Ae/As interruptions required 5.0% to 115.5% longer recovery times compared to one-day interruptions in AE-D and AN-D systems. According to amoA activity, 60.8 h were required in AE-D systems to establish new temporary SS after As interruptions, and RNA amoA copies (copy number/microliter) decreased 88.5%, while 287.2 h were required in AN-D systems, and RNA amoA copies (copy number/microliter) increased 36.4 times. For nirS activity, 75.2–85.8 h were required to establish new SSs after Ae and As interruptions. The results suggested that new temporary SS formation and recovery in terms of DO, pollutant REs and amoA and nirS gene activities could be modelled by logistic functions. It is concluded that temporary SS formation and recovery after Ae and As interruptions occurred at asynchronous rates in terms of DO, pollutant REs and amoA and nirS gene activities. Because of DO fluctuations, the quantitative relationship between gene activity and pollutant RE remains a challenge.

scholarly journals The Urban River Syndrome: Achieving Sustainability Against a Backdrop of Accelerating Change

2021 ◽  
Vol 18 (12) ◽  
pp. 6406
Author(s):  
Martin Richardson ◽  
Mikhail Soloviev
Keyword(s):  
River Restoration ◽  
Native Species ◽  
Systems Approach ◽  
Similar Type ◽  
Urban River ◽  
Urban Rivers ◽  
River Ecology ◽  
Spatial And Temporal Scales ◽  
Natural Systems ◽  
Urban River Restoration

Human activities have been affecting rivers and other natural systems for millennia. Anthropogenic changes to rivers over the last few centuries led to the accelerating state of decline of coastal and estuarine regions globally. Urban rivers are parts of larger catchment ecosystems, which in turn form parts of wider nested, interconnected systems. Accurate modelling of urban rivers may not be possible because of the complex multisystem interactions operating concurrently and over different spatial and temporal scales. This paper overviews urban river syndrome, the accelerating deterioration of urban river ecology, and outlines growing conservation challenges of river restoration projects. This paper also reviews the river Thames, which is a typical urban river that suffers from growing anthropogenic effects and thus represents all urban rivers of similar type. A particular emphasis is made on ecosystem adaptation, widespread extinctions and the proliferation of non-native species in the urban Thames. This research emphasizes the need for a holistic systems approach to urban river restoration.

scholarly journals Urban Rivers Corridors in the Don Catchment, UK: From Ignored, Ignoble and Industrial to Green, Seen and Celebrated

2021 ◽  
Vol 13 (14) ◽  
pp. 7646
Author(s):  
Ed Shaw ◽  
Debbie Coldwell ◽  
Anthony Cox ◽  
Matt Duffy ◽  
Chris Firth ◽  
...  
Keyword(s):  
Industrial Revolution ◽  
Urban River ◽  
Urban Rivers ◽  
River Habitat ◽  
Negative Perceptions ◽  
High Degree ◽  
River Corridors ◽  
Advance Knowledge ◽  
Ecological Recovery

Research on urban rivers often seeks to find commonalities to advance knowledge of the effect of urbanisation on rivers, and rightly so. But it is important, also, to develop a complementary understanding of how urban rivers can be distinct, to facilitate a more nuanced view of concepts such as the ‘urban river syndrome’ and of the challenges facing those who wish to create more sustainable urban river corridors. To this end we use the Don Catchment as a case study to illustrate how historic patterns of urbanisation have been fundamental in shaping the catchment’s rivers. Following the Industrial Revolution, the catchment became an industrial centre, resulting in the ecological death of river ecosystems, and the disconnection of communities from stark urban river corridors. Widescale deindustrialisation in the 1970s and 1980s then resulted in a partial ecological recovery of the rivers, and ignited public interest. This history has imbued the catchment’s urban river corridors with a distinctive industrial character that can vary greatly between and within settlements. It has also left a legacy of particular issues, including a high degree of river habitat fragmentation and physical modification, and of negative perceptions of the rivers, which need improving to realise their potential as assets to local communities.

A study of water quality in an urban river and potential improvement using a prototype instream aerator

1989 ◽  
Vol 16 (3) ◽  
pp. 308-316 ◽  
Author(s):  
C. A. Town ◽  
D. S. Mavinic ◽  
B. Moore
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Data Base ◽  
Chlorophyll A ◽  
Late Summer ◽  
Urban River ◽  
Agricultural Activity ◽  
Fish Kills ◽  
Low Dissolved Oxygen ◽  
Oxygen Levels

Urban encroachment and intensive agricultural activity within the Serpentine–Nicomekl watershed (near Vancouver, B.C.) have caused a series of fish (salmon) kills on the Serpentine River since 1980. Low dissolved oxygen was responsible for these kills. This field project investigated some of the dynamic chemical and biological relationships within the river, as well as the use of an instream aerator as a temporary, in situ, water quality improvement measure. Weekly sampling for a 6-month period during the latter half of 1985 established a solid data base for deriving and interpreting meaningful interrelationships. A strong correlation between chlorophyll a and dissolved oxygen levels before the algae die-off supported the hypothesis that algae blooms dying in the fall could create a serious oxygen demand. Because of these environmental conditions, the river is unable to sustain healthy dissolved oxygen levels during this period. As such, a prototype, 460 m artificial aeration line was designed, installed, and monitored to evaluate its potential for alleviating low dissolved oxygen conditions and improving overall water quality during the critical fall period.The instream aerator ran continuously for over 2 months, starting in September 1985. Despite better-than-expected weather conditions (i.e., cool, wet weather) and relatively high dissolved oxygen levels during the fall of 1985, the data base appeared to support the use of this prototype aeration unit as a means of "upgrading" a stretch of an urban river subject to periodic, low dissolved oxygen levels. As a result, a 2-year follow-up study and river monitoring was initiated. In both 1986 and 1987, late summer and early fall river conditions resulted in the potential for serious salmon kills, due to higher-than-normal river temperatures and very low dissolved oxygen. In both instances, the instream aerator prevented such fish kills in a key stretch of the river. Expansion of the system to include other critical stretches of the Serpentine and other urban river systems, near Vancouver, is being considered. Key words: algae, aerator, chlorophyll a, eutrophic, fish kills, instream aeration, river improvement, urban river.

scholarly journals Functional Characterization and Diversity of Ammonia-Oxidizing Microorganisms in Streams South of the Dabie Mountains, China

2018 ◽  
Author(s):  
Amjed Ginawi ◽  
Wang Lixiao ◽  
Huading Wang ◽  
Bingbing Yu ◽  
Yan Yunjun
Keyword(s):  
Quantitative Polymerase Chain Reaction ◽  
Functional Characterization ◽  
Physiological Adaptation ◽  
Ammonia Oxidizing Bacteria ◽  
Dabie Mountains ◽  
Natural Habitats ◽  
Environmental Pressures ◽  
Microbial Structures ◽  
Ammonia Oxidizing Archaea ◽  
Positive Correlations

Ammonia-oxidizing microorganism communities are abundant and functionally efficacious in nitrification. However, ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) groups complicate this process in subtropical streams. This study investigates the abundance of ammonia-oxidizing communities south of the Dabie Mountains, China, using quantitative polymerase chain reaction (qPCR). Clone libraries were utilized to analyze the abundance and microbial structures of AOA and AOB in sediments. Such analysis may provide strong evidence reflecting the links within the environment. The results show that AOB had a lower abundance of copies of the ammonia-oxidizing gene (amoA) than AOA. Interestingly, the AOA and AOB community compositions were correlated with ecological characteristics. The dissolved oxygen (DO) and oxidation-reduction potential (ORP) had significant positive correlations, whereas the phosphorus within the structure had a negative correlation with the abundance of both groups. Our study shows that it might adopt some species related to Nitrosotalea clusters that can resist comparably higher pH (toward pH 6.5). Together, these results imply that the physiological adaptation of microbial guilds to environmental pressures in ammonia-oxidizing archaea might allow them to have a more substantial function of ammonia-oxidizing communities in natural habitats.

scholarly journals Modelling Dissolved Oxygen Depression in an Urban River in China

Water ◽  
2017 ◽  
Vol 9 (7) ◽  
pp. 520 ◽  
Author(s):  
Jingshui Huang ◽  
Hailong Yin ◽  
Steven Chapra ◽  
Qi Zhou
Keyword(s):  
Dissolved Oxygen ◽  
Urban River
Sign in / Sign up

Export Citation Format

Share Document