Shanghai River Research Articles

Riverine CH4 and CO2 emissions respond to associated agricultural land use and seasonality

ABSTRACT Recently, agricultural land use has significantly impacted carbon emissions and water quality in adjacent rivers. This study examined the influence of land-use types and seasonality on carbon emissions from agriculture-impacted rivers in Shanghai. Our results showed that the crop farming land-use-associated river (AR) had CH4 and CO2 fluxes 2.68 and 3.47 times higher, respectively, than those in the aquaculture land-use-AR and 2.86 and 2.81 times higher than in the livestock and poultry breeding land-use-AR. Statistical analyses revealed that total nitrogen, ammonia nitrogen, and humification index were significantly correlated with crop farming land-use-AR carbon emissions. Conversely, no clear correlation was found between chemical factors and carbon fluxes in the aquaculture land-use-AR and livestock and poultry breeding land-use-AR due to the complexity of pollution sources. Seasonality significantly influenced CH4 and CO2 fluxes from agriculture-impacted rivers, with carbon fluxes in summer being 3.5 and 2.5 times higher than in winter, respectively. Crop farming land-use-AR carbon fluxes exhibited the highest variability under seasonal influences. This study emphasizes the need for policies to mitigate agricultural land use impacts on river carbon emissions.

Research Progress on Production and Emission of CH4 and N2O from Urban Rivers

Methane （CH4） and nitrous oxide （N2O） are concerning greenhouse gases. Urban rivers have been important emission sources of CH4 and N2O in recent years. It is meaningful for city greenhouse gas reduction to provide a systematic analysis of spatiotemporal characteristics, mechanisms, and influencing factors of the production and emission of CH4 and N2O from urban rivers. This study combed measured data of urban river CH4 and N2O dissolution concentrations and emission fluxes from related literature published in the past 20 years and also concluded the spatiotemporal characteristics of urban river CH4 and N2O emissions. This study estimated that CH4 and N2O emissions （expressed by CO2-eq） from urban rivers in Beijing were 234.63 and 59.53 Gg CO2-eq in 2018, whereas CH4 and N2O emissions （expressed by CO2-eq） from urban rivers in Shanghai were 159.86 and 260.24 Gg CO2-eq in 2018, respectively. These results demonstrated that urban rivers have become important CH4 and N2O emission sources. This study summarized the production/consumption processes and import/export pathways of CH4 and N2O in urban rivers. What is more, this study discussed the main influencing factors of urban river CH4 and N2O production and emissions from the perspectives of river environmental conditions and urbanization effects. At last, the present work prospected the future research trends of urban river CH4 and N2O emissions and provides urban rivers with scientific support for greenhouse gas reduction.

Coleps shanghaiensis n. sp. challenges the validity of the genus Levicoleps (Ciliophora, Prostomatida)

Coleps is a common genus of pelagic ciliates in freshwater and brackish water habitats. Classification and phylogeny of Coleps species are, however, still full of confusion. In this study, we investigated Coleps shanghaiensis n. sp., collected from a river in Shanghai, China, by living observation, protargol staining, and molecular methods. Coleps shanghaiensis is about 70–90 µm × 35–55 µm in size, has a barrel-shaped body with three posterior spines, and possesses 21–24 ciliary rows, each composed of two perioral dikinetids and 19–22 monokinetids, and six caudal cilia. In SSU rRNA gene phylogenies, C. shanghaiensis fell within the clade of subspecies of Levicoleps biwae, which questions the validity of the genus Levicoleps. Furthermore, the biogeography of the genus Coleps is discussed.

Research on Satellite and Ground Multi-Sensor Collaborative Sensing Method for Floating Plants

Abstract. Dynamic monitoring of water environment is the basis of maintaining urban security and promoting urban sustainable development. To effectively solve the problems caused by the large-scale flooding of floating aquatic invasive plants, such as water environment destruction, clogging river, water quality pollution, water ecological balance destruction, etc., a satellite and ground multi-sensor collaborative sensing method for floating plants is proposed in this paper. For the monitoring of floating plants in macro watershed, the vegetation index and chlorophyll concentration were used to extract floating plants, analyzing, and calculating the distribution and coverage area of floating plants based on 4-band high-resolution satellite images. For the monitoring of floating plants in small watershed, combined with visible light video, multispectral images, and LiDAR data, optimized spectral feature variable processing, semantic segmentation network, and symmetric function neural network are utilized to obtain real-time information on the invasion location, distribution pattern, and coverage area of floating plants. In this paper, the upstream basin of the Huangpu River in Shanghai in 2023 was selected as the experimental area. The distribution of floating plants in different watercourse and different periods was successfully obtained by this method, and the coverage area was accurately calculated with an identification rate of more than 90%, which provided technical support for cross-regional management and efficient cleaning of floating plants.

Assessing public perceptions of the cultural ecosystem services waterfront spaces provide along the Huangpu River in Shanghai, China, in support of urban waterfront planning and design

Assessing public perceptions of the cultural ecosystem services waterfront spaces provide along the Huangpu River in Shanghai, China, in support of urban waterfront planning and design

Analyzing the public spaces along the Huangpu River from the aspects of sustainable development

In recent years, the Huangpu River in Shanghai has paid great attention to urban renewal and ecosystem reconstruction. However, with the development of the city, it also faces many challenges such as inappropriate urban planning and environmental pollution. In this paper, after organizing the existing cases of the old wharves and public green spaces along the Huangpu River, an evaluation system is constructed by selecting indicators from the aspects of sustainable development and ecological environment, and urban planning. They are analyzed and compared from the process of planning and renovation of public spaces in various areas along the riverfront on both sides of the Huangpu River, and the current situation and existing problems are summarized. Finally, the study compares Shanghai with similar waterfront cities, highlights and criticizes Shanghai's urban development process, and gives reasonable suggestions on its ecological environment and sustainable development level, so as to provide references for the renewal of urban public space in the future.

A calculation algorithm for ship pollutant gas emissions and diffusions based on real-time meteorological conditions and its application

Most literature focusing on the issue of ship pollutant emission and diffusion is based on static meteorological conditions. The relevant literature seldom analyzes the emission and diffusion of ship pollutant gas according to real-time meteorological data when wind direction, wind speed and other meteorological conditions have changed. This paper presents a fast translational diffusion algorithm, and empirically demonstrates it through ship and meteorological data from the Huangpu River field in Shanghai. First, CO2 emissions were estimated using the actual speed of the ship engine changed under the influence of variable wind, and simulation analysis was performed to the scenario of hourly diffusions. The research findings are as follows: In comparison with the traditional algorithms, the fast algorithm can significantly improve calculation efficiency, save calculation time and achieve the long-distance and long-time parallel calculation of multiple ships. As proven by the empirical research using the ships on Huangpu River in Shanghai, the maximum difference of CO2 emissions is 34.5%, 36.85% and 19.97% respectively after upwind, downwind and real-time meteorological conditions are taken into account. The research finding indicates that wind direction changes have a greater impact on the carbon emission of ships.

Research on Social Service Effectiveness Evaluation for Urban Blue Spaces—A Case Study of the Huangpu River Core Section in Shanghai

Urban blue spaces (UBSs) hold significant value in terms of public health, tourism economy, and residents’ well-being. The Huangpu River in Shanghai, renowned as a global urban blue space, currently faces challenges such as unequal service capacity across sections and varying levels of spatial vitality. This study incorporates the concept of “service effectiveness” into public space evaluation. Drawing inspiration from the 4E (economics, efficiency, equity, and effectiveness) principles of effectiveness evaluation, a social service effectiveness evaluation system is constructed to measure service efficiency and effect. Through the literature research, 6 primary indicators and 12 secondary indicators are set to investigate the utilization rate and realization effect of the UBS. The evaluation system utilizes field surveys, text analysis, and remote-sensing techniques to collect relevant data. Through standardized calculations, different aspects of the indicators are integrated into a single evaluation criterion. The “overall effectiveness index” and the “efficiency–effect balance index” is introduced to quantitatively analyze the overall effectiveness characteristics, including spatial characteristics and time-varying characteristics, as well as efficiency–effect balance and imbalances. The evaluation located three low-effectiveness sections and three imbalanced sections at the north and south ends of the core section of the Huangpu River. The influence factors of effectiveness are analyzed through correlation test and literature studies, mainly including the urban hinterland, service facilities, environmental quality, and management publicity factors. This study aims to provide research ideas and methods for waterfront area planning and city-refined management.

Seasonal Variation Characteristics and Pollution Assessment of Heavy Metals in Water and Sediment of Taipu River

Taipu River is a river spanning two provinces and one city in a demonstration area in the Yangtze River Delta on an ecologically friendly developmentand an important water source in the upper reaches of the Huangpu River in Shanghai. To understand the multi-media distribution characteristics, pollution status, and ecological risk of heavy metals in the Taipu River, the contents of heavy metals (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, and Zn) in the sediments of Taipu River were analyzed, and the pollution status and potential ecological risk were evaluated using the Nemerow comprehensive pollution index, geo-accumulation index, and potential ecological risk index methods. In addition, the health risk assessment model was used to assess the health risk of heavy metals in surface water of Taipu River. The results showed that the concentrations of Cd, Cr, Mn, and Ni in the surface water of Taipu River exceeded the class Ⅲ water limit at the upstream point in spring; the concentrations of Sb exceeded the class Ⅲ water limit at all points in winter; the average value of As exceeded the class Ⅲ water limit in overlying water during the wet season; and the average values of As and Cd exceeded the class Ⅲ water limit in pore water during the wet season. The health risk assessment of surface water implied that both adults and children had higher health risk in spring and lower health risk in other seasons. The health risk of children was significantly higher than that of adults, and it mainly came from chemical carcinogenic heavy metal elements As, Cd, and Cr. The average contents of Co, Mn, Sb, and Zn in Taipu River sediments in the four seasons all exceeded the Shanghai soil baseline; the average contents of As, Cr, and Cu in summer, autumn, and winter exceeded the Shanghai soil baseline; and the average contents of Cd, Ni, and Pb in summer and winter exceeded the Shanghai soil baseline. The evaluation results of the Nemerow comprehensive pollution index and geo-accumulation index showed that the pollution degree of the middle reaches of Taipu River was higher than that of the upper and lower reaches, and the Sb pollution was more serious. The potential ecological risk index method revealed that the Taipu River sediment was at a low risk. Cd had a high contribution in both the wet and dry seasons and could be regarded as the main heavy metal of potential ecological risk in the Taipu River sediment.

The investigation of the physiochemical factors and bacterial communities indicates a low-toxic infectious risk of the Qiujiang River in Shanghai, China.

The overall water quality of urban rivers is closely related to the community structure and the physiochemical factors in them. In this study, the bacterial communities and physiochemical factors of the Qiujiang River, an important urban river in Shanghai, were explored. Water samples were collected from nine sites of the Qiujiang River on November 16, 2020. The water quality and bacterial diversity were studied through physicochemical detection, microbial culture and identification, luminescence bacteria method, and 16S rRNA Illumina MiSeq high-throughput sequencing technology. The water pollution of the Qiujiang River was quite serious with three water quality evaluation indexes, including Cd2+, Pb2+, and NH4+-N, exceeding the Class V standard set by the Environmental Quality Standards for Surface Water (China, GB3838-2002), while the luminescent bacteria test indicated low toxicity of nine sampling sites. Through 16S rRNA sequencing, a total of 45 phyla, 124 classes, and 963 genera were identified, in which Proteobacteria, Gammaproteobacteria, and Limnohabitans were the most abundant phylum, class, and genus, respectively. The Spearman correlation heatmap and redundancy analysis showed that the bacterial communities in the Qiujiang River were correlated with pH; the concentrations of K+, and NH4+-N, and the Limnohabitans were significantly correlated with the concentrations of K+, and NH4+-N in the Zhongyuan Road bridge segment. In addition, opportunistic pathogens Enterobacter cloacae complex and Klebsiella pneumoniae in the samples collected in the Zhongyuan Road bridge segment and Huangpu River segment, respectively, were successfully cultured. The Qiujiang River was a heavily polluted urban river. The bacterial community structure and diversity were greatly affected by the physiochemical factors of the Qiujiang River, and it displayed low toxicity while a relatively high infectious risk of intestinal and lung infectious diseases.

Dissolved Potentially Toxic Elements in the Megacity River Network of Shanghai, China

Riverine water exposed to potentially toxic element (PTE) contamination is a vital concern worldwide due to its severe impact on ecosystems, economies, and human health. In this research, the pollution level, sources, behavior, and potential health risks of Li, Fe, As, Sr, Sb, and Pb in the Shanghai river network (SRN) during the high-flow season were comprehensively investigated and evaluated. The results showed that the six PTE concentrations (μg/L) ranked (207.05) > Fe (11.30) > Sb (6.95) > Li (6.16) > As (3.45) > Pb (0.02). The heavy-metal pollution index (HPI) and Nemerow index (NI) revealed the moderate-to-heavy to heavy pollution of studied PTEs with the mean values of 74.00 and 0.98, respectively. As and Sb were found to be the major contributors to the total toxic risk according to the hazard quotient/index (HQ/HI). The HI value of Sb for children exceeded 1, which indicated an obvious noncarcinogenic health risk via ingestion and dermal absorption exposure pathways, with children at higher risk. The possible origins of pollution were recognized as the geogenic process (Li, Fe, and Sr), industrial waste (Sb), and the combined action of agricultural and industrial activities (As and Pb) by the methods of correlation analysis (CA) and principal component analysis (PCA). Overall, the geochemistry behavior of PTEs in the dissolved phase displayed the potential for tracing regional environmental management levels, especially in a megacity.

Interpolation Technique for the Underwater DEM Generated by an Unmanned Surface Vessel

High-resolution underwater digital elevation models (DEMs) are important for water and soil conservation, hydrological analysis, and river channel dredging. In this work, the underwater topography of the Panjing River in Shanghai, China, was measured by an unmanned surface vessel. Five different interpolation methods were used to generate the underwater DEM and their precision and applicability for different underwater landforms were analyzed through cross-validation. The results showed that there was a positive correlation between the interpolation error and the terrain surface roughness. The five interpolation methods were all appropriate for the survey area, but their accuracy varied with different surface roughness. Based on the analysis results, an integrated approach was proposed to automatically select the appropriate interpolation method according to the different surface roughness in the surveying area. This approach improved the overall interpolation precision. The suggested technique provides a reference for the selection of interpolation methods for underwater DEM data.

Revealing the spatiotemporal characteristics and drivers of the block-scale thermal environment near a large river: Evidences from Shanghai, China

Urban rivers play an important role in mitigating surrounding temperatures but empirical research on the thermal environment near large rivers remains sparse and the influencing factors are still unclear. In this study, mobile measurement of the air temperature (Ta) was conducted in summer (July 2021) and winter (December 2021 and January 2022) in an urban area near Huangpu River in Shanghai, China. Four factors: river proximity, ventilation, urban morphology and land use were considered as the potential drivers. A GeoDetector Model (GDM) was used to investigate the contributions of these drivers and their interactions for the uneven distribution of Ta. This study identified that in both seasons, the Ta distribution at block scale showed spatiotemporal variation and exhibited different degrees of stratified heterogeneity at the levels of four potential drivers. Enhancements were found between pairs among the drivers, with maximum explanatory power reaching 96% and 82% for the summer and winter Ta distributions, respectively, suggesting that the thermal environment of the riverfront is driven by a combination of factors. The dominant factors include river proximity, urban morphology and land use, and the urban morphology factor can strongly influence the regulation effect of the river. Moreover, the design of the riverfront open space was also found to have a non-negligible influence. Therefore, it is suggested to consider the dominant factors as well as the interaction between factors according to the target time. Findings in this study give insights for the practice of climate adaptive planning and design on urban riverfront.

Insights into the Seasonal Olfactory Mechanism of Geosmin in Raw Water of Huangpu River.

Since the 1990s, the raw water of Huangpu River in Shanghai, China, has intermittently encountered off-flavor contamination. In this work, the concentrations of typical odor, geosmin, in raw water of Huangpu River are found to shift along with the seasons. However, microbes recognized as the producer of geosmin such as Cyanobacteria and Actinobacteria are not consistent with the shift of geosmin. Cyanobacteria blooms in summer rather than winter, whereas Actinobacteria thrives in winter. Representational difference analysis (RDA) reveals that microbes associated with blooming algae have positive co-occurrence correlations with the concentrations of geosmin and nutrients in winter, whereas those within Cyanobacteria and Planctomycete are in a positive correlation with temperature and thrive in summer. This causes the concentration of geosmin in raw water to appear to depend on the abundance of Actinobacteria rather than that of Cyanobacteria. However, combining with the synthesis and storage properties of geosmin in algae, as well as the decomposition properties of algae with Actinobacteria, geosmin might be synthesized by Cyanobacteria in summer, which is stored in cells of Cyanobacteria and released only via the decomposition of Actinobacteria in winter. This potential olfactory mechanism of geosmin is quite different from that derived from pure culture of odor producers or correlation analysis of bacteria and odors; thus, providing insights into the mechanism of practical off-flavor events.

A ship emission diffusion model based on translation calculation and its application on Huangpu River in Shanghai

Under global warming, how to accurately measure and reduce ship emissions has become an important issue concerned by the transportation sector and the whole society. The diffusion concentration of continuous ship emissions is calculated by the emission concentrations at the time of observation. With the increase of observation time window, diffusion distance, and calculation accuracy, the calculation time of traditional algorithms and the requirements for computing resources increase exponentially. Therefore, this paper proposes a fast algorithm based on data translation (matrix translation and point translation algorithms), which can calculate the emission diffusion concentration of multiple ships, long distances and long duration while ensuring the accuracy. The time complexity of the traditional algorithm and the fast algorithm are O(kT2) and O(kT) respectively, and the fast algorithm can greatly improve the computing efficiency and save the computing time. The matrix translation algorithm is suitable for small-scale calculations with a fixed observation window, the amount of data is relatively small, and the calculation speed is the fastest. The point translation algorithm is suitable for large-scale calculations with a moving observation window and can adjust the calculation accuracy flexibly, but the data size is large and difficult to predict. Finally, in the numerical simulation on the Huangpu River, millions of emission concentrations data, based on trajectory information in 12 h over eight vessels, were calculated only in several minutes, which proves the high efficiency of the fast algorithm.

An approach to urban landscape character assessment: Linking urban big data and machine learning

Diverse urban landscape is an important cultural driving force for urban sustainable development. Although characterizing landscape to protect landscape diversity is widely used in regional landscape and preservation practices, it is difficult to apply to urban landscape character assessment, which needs fine-scale data support, explicit study units, and effective clustering models. Therefore, this study uses urban big geospatial data and machine learning technology to establish a technical system for character assessment of urban landscape applicable to the block scale and complete the landscape assessment of urban areas of Beijing and Shanghai, China. A total of 64 landscape character types were identified in Beijing, and 61 in Shanghai. We find that (1) urban landscape characters are different with the ring road as the boundary, but each zone presents a combination of different proportions of landscape characters. (2) Beijing's city wall demolition policy is affected by historical protection policy. Landscape differentiation on both sides of the Huangpu River in Shanghai has yet to be realized. This study extends the theory of LCA and realizes the research exploration of urban built environment. It can also be used to guide urban zoning control, evaluate planning policy, and provide assistance in practice for sustainable urban development and management.

Occurrence Characteristics of Inorganic Nitrogen in Groundwater in Silty-Clay Riparian Hyporheic Zones under Tidal Action: A Case Study of the Jingzi River in Shanghai, China

For comprehending the effect of tidal action on nitrogen cycle in silty-clay riparian hyporheic zones, the synchronous monitoring of water level and water quality was carried out along a test transect during a spring tidal period from 21 to 23 October 2021. Moreover, the permeability and chemical composition of soil samples from drilled holes were measured. Subsequently, the spatiotemporal variation of inorganic nitrogen concentrations in the groundwater in the riparian hyporheic zone was investigated during the study period, and the potential reason was discussed. It is shown that the delayed response time of groundwater level in the silty-clay riparian zone to the tide-driven fluctuation of the river stage increased with distance from the shore and reached 3.0 h at the position 3.83 m away from the shore. The continuous infiltration of the river water under tide action contributed to the aerobic and neutral riparian hyporheic zone conductive to nitrification. Within 4 m away from the bank, the dominant inorganic nitrogen form changed from NO3−-N to NH4+-N, upon increasing the distance from the bank. Additionally, the removal of nitrogen could occur in the riparian hyporheic zone with aerobic and neutral environment under the conjoint control of nitrification, microbial assimilation, and aerobic denitrification.

Occurrence, health risk assessment and water quality criteria derivation of six personal care products (PCPs) in Huangpu River, China.

Personal care products (PCPs) have shown adverse health effects on humans. However, their health risk associated with fish consumption and relevant water quality criteria are still not well documented. This study investigated the occurrence and health risk of six PCPs (triclosan, bisphenol-A, and four commonly used organic ultraviolet (UV) filters, i.e., homosalate (HMS), 4-methylbenzylidene camphor (4-MBC), oxybenzone (BP-3), and octocrylene (OC)). River water and three trophic levels of fish species were collected from Huangpu River in Shanghai. The concentration range of the six PCPs were 1.48-89.76ng/L in water and 0.40-10.75ng/g dry weight in fish. Estimated daily intake (EDI) and target hazard quotient (THQ) of the PCPs indicated that consuming these fish would not pose non-carcinogenic risks. The maximum allowable fish consumption rates ranged from 85 to 1760 and 155 to 3230 meals per month for children and adults, respectively. As to the four organic UV filters, it is the first time to report the fish consumption advisories. Finally, the human health ambient water quality criteria (AWQC) values of HMS, 4-MBC, BP-3, OC, TCS, and BPA (i.e., 0.1218, 0.7311, 0.3494, 0.0477, 235.8, and 154.7μg/L, respectively) were proposed, and they can serve as a valuable technical reference for global development and revision of aquatic environmental quality standards for these emerging contaminants.

Calculation method of submerged plant biomass in small and medium urban rivers: Based on the investigation and analysis of Shanghai City

沉水植物的盖度和生物量是衡量浅水系统恢复程度的重要指标，但城市河道沉水植物的生境由于人为干扰及修复过程，具有较高的异质性，使得城市河道沉水植物盖度和生物量测定更加困难，目前尚无准确、快速的计算方法.本研究以上海市内中小河道为研究对象，通过实测4条河道330余个代表样方的沉水植物生物，研究了基于采样次数的沉水植物单位面积生物量计算方法、采样布点方法和河道总盖度测算方法.结果显示：（1）至少需30~35次面积为0.04 m²的采样可准确估算上海中小河道内沉水植物单位面积的生物量；（2）样点设置可选用随机或等距设置；（3）利用Rededge-M多光谱相机对河道拍摄5波段影像，并进行5~8次重复处理，可较为准确获得整条河道沉水植物盖度.本研究可为城市中小河道沉水植被恢复、河道的分类管理与保护提供参考及依据.;The coverage and biomass of submerged plants are the key indicators of the restoration level of shallow water systems. But the habitat of submerged plants in urban rivers usually has high heterogeneity because of the human disturbance and restoration process. This makes it more difficult to determine the coverage and biomass of submerged plants in urban rivers and lacks an accurate and fast method. In this study, we measured the biomasses of submerged plants in more than 330 representative plots in 4 rivers to investigate the method of calculating the biomass per unit area of submerged plants using the numbers of samplings, as well as the methods of sampling and calculation of total coverage of submerged plants in rivers. The results showed that:(1) At least 30 to 35 samplings (0.04 m²) are required to accurately estimate the biomass per unit area of submerged plants in small and medium rivers in Shanghai; (2) Random or equidistant setting can be selected for sample setting; (3) Getting the band-5 images of the river channels using the Rededge-M multi-spectral camera image and repeating the process for 5 to 8 times, the coverage of submerged plants in the rivers can be obtained with higher accuracy. This study provides crucial reference and knowledge for the restoration of submerged vegetation in small and medium urban rivers and the management and protection of rivers.

Investigation of dissimilatory nitrate reduction to ammonium (DNRA) in urban river network along the Huangpu River, China: rates, abundances, and microbial communities.

Dissimilatory nitrate reduction to ammonium (DNRA) is an essential intermediate step in the nitrogen cycle, and different sediment physicochemical properties can affect the DNRA process. But the detailed research on the environmental nitrogen cycling in urban river networks based on DNRA communities and the functional gene nrfA is lacking. In this study, the flow line of the Huangpu River in Shanghai was analyzed using isotope tracer, quantitative real-time PCR, and high-throughput sequencing techniques to evaluate the role of DNRA on the stability of the river network and marine. The significant positive correlation between the rate of DNRA and sediment organic carbon was identified. At the genus level, Anaeromyxobacter is the most dominant. Notably, both heterotrophic and autotrophic DNRA species were discovered. This study added diversity to the scope of urban freshwater river network ecosystem studies by investigating the distribution of DNRA bacteria along the Huangpu River. It provided new insights into the biological nitrogen cycle of typical urban inland rivers in eastern China.