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Microplastic particles (MPs), which have been considered as emerging contaminants, are widely found in water environments. In southern China, many apartment owners place washing machines on their balconies, where the separated drain system usually leads to the storm-water pipes, resulting in releasing MPs directly into the environment. In the present study, we firstly obtained the laundry preference of residents in the study area based on a questionnaire survey and then designed a simulated laundry experiment to determine the MFs shed in the laundry process. The approximate amount of MFs discharged into the environment under various scenarios was estimated. The results showed that type of washing machine and detergent had a great influence on the MFs shedding. The use of a front-load machine and liquid laundry detergent pods (LDPs) can reduce MFs shed in the laundry process. If the laundry effluent generated by washing machines placed on apartment balconies flows into the municipal pipe network and is treated by wastewater treatment plants (Andrea Menéndez-Manjón), the environmental load of MFs can be reduced. Taking Nanning, the capital city of Guangxi Zhuang Autonomous Region, as a case study, the calculated result shows that the number of MFs discharged into the environment decreased by 93% at the optimized laundry mode. This study provides a reference for the control of MFs and the rational revision of the Architectural Design Guidelines in subtropical cities equipped with the diversion drainage system. [Display omitted] • Laundry preferences of the residents were obtained based on the questionnaire survey. • Parameters of MFs release in laundry process were tested by simulating experiments. • Doing laundry on balcony may release MFs into environment via rain drainage. • Use of laundry detergent pods can reduce the shedding of MFs by 82%. • WWTPs can reduce the environmental load of MFs sourced from laundry wastewater. [ABSTRACT FROM AUTHOR]

• Urban storm sewer system discharges frequently contained elevated E. coli levels. • Storm discharges consisted of human, avian, ruminant, and dog fecal sources. • Fecal sources varied between 'wet' and 'dry' weather discharge conditions. • Catchment land use was significantly correlated with human and dog fecal sources. • 'Dry' weather discharges often contained substances that bias DNA recovery. Urban areas are built environments containing substantial amounts of impervious surfaces (e.g., streets, sidewalks, roof tops). These areas often include elaborately engineered drainage networks designed to collect, transport, and discharge untreated stormwater into local surface waters. When left uncontrolled, these discharges may contain unsafe levels of fecal waste from sources such as sanitary sewage and wildlife even under dry weather conditions. This study evaluates paired measurements of host-associated genetic markers (log 10 copies per reaction) indicative of human (HF183/BacR287 and HumM2), ruminant (Rum2Bac), canine (DG3), and avian (GFD) fecal sources, 12-hour cumulative precipitation (mm), four catchment land use metrics determined by global information system (GIS) mapping, and Escherichia coli (MPN/100 ml) from seven municipal separate storm sewer system outfall locations situated at the southern portion of the Anacostia River Watershed (District of Columbia, U.S.A.). A total of 231 discharge samples were collected twice per month (n = 24 sampling days) and after rain events (n = 9) over a 13-month period. Approximately 50 % of samples (n = 116) were impaired, exceeding the local E. coli single sample maximum of 2.613 log 10 MPN/100 ml. Genetic quality controls indicated the absence of amplification inhibition in 97.8 % of samples, however 14.7 % (n = 34) samples showed bias in DNA recovery. Of eligible samples, quantifiable levels were observed for avian (84.1 %), human (57.4 % for HF183/BacR287 and 40 % for HumM2), canine (46.7 %), and ruminant (15.9 %) host-associated genetic markers. Potential links between paired measurements are explored with a recently developed Bayesian qPCR censored data analysis approach. Findings indicate that human, pet, and urban wildlife all contribute to storm outfall discharge water quality in the District of Columbia, but pollutant source contributions vary based on 'wet' and 'dry' conditions and catchment land use, demonstrating that genetic-based fecal source identification methods combined with GIS land use mapping can complement routine E. coli monitoring to improve stormwater management in urban areas. [Display omitted] [ABSTRACT FROM AUTHOR]

• Stormwater drainage system as infrastructure protecting cities from heavy rainfall. • Problems in designing stormwater drainage due to limited short-term rainfall data. • The STORAGE model as an effective tool for determining short-duration rainfall. • The STORAGE model as a tool supporting the determination of urban flood areas. • Application the STORAGE model for the urban landscape planning. In this investigation, we evaluated the applicability of the Stochastic Rainfall Generator (STORAGE) as a data source for deriving design hydrographs in urban catchments. This assessment involved a comparison with design rainfall calculated using Intensity-Duration-Frequency (IDF) curves derived from observed time-series data. The resulting design rainfall values from both methods were incorporated into a hydrodynamic model of the storm sewer network. To simulate peak discharge and flood areas, the Storm Water Management Model (SWMM) program was employed in conjunction with SCALGO. Our findings indicate that design rainfall values obtained from the STORAGE model exceeded those derived from the observed time-series, with a more pronounced difference for shorter rainfall durations. Simulations further revealed that peak runoff disparities between the two approaches were most evident at a 0.10 probability of exceedance compared to a 0.01 probability. Hydrodynamic simulations demonstrated that the flooding volume induced by design rainfall based on the STORAGE model surpassed that resulting from observed rainfall. Across all events, both the flooding volume and area from STORAGE were consistently greater than those derived from IDF curves. The integration of the SWMM model with the SCALGO application introduced a novel functionality for dynamic visualization of flooding, offering valuable insights for effective flood management in urban areas. [Display omitted] [ABSTRACT FROM AUTHOR]

Though urban sewer is an important CH4 emission source, it is impractical to assess overall CH4 emission from massive and closed underground sewer networks through either online or off-line measurements owing to the complexity in construction and operation of sewer systems and highly variable wastewater quality. Here, we develop a feasible method based on emission factors and official statistical data for overall CH4 estimation from sewers. By using this method, we show that the CH4 emissions from sewers in China was 0.6185 Tg in 2019 and the national mean of the per capita CH4 emission from sewers was 1361 g cap-1. We find that temperature significantly correlates with sewer CH4 emissions specified with population or sewage quantity. We further argue that economic growth and urban infrastructure management also affect the CH4 emissions from sewers or surface waters due to sewage leakage/discharge. Our proposed method is practical for the sewer CH4 estimation worldwide. • A feasible method for overall CH 4 estimations from sewer systems was developed. • Complex structure and highly variable conditions in sewers are avoided with this method. • CH 4 emissions from sewers in China was 0.6185 Tg in 2019. • The national mean of the per capita CH 4 emission from sewers was 1361 g cap−1. [ABSTRACT FROM AUTHOR]

Surface water runoff can transport contaminants offsite to downstream aquatic ecosystems. The prevalence of impervious surfaces in urban areas enhances surface runoff and contributes to contamination of urban surface streams. Urban areas have complex drainage systems for the conveyance of drainage water, however, there is a dearth of information on the distribution of contaminants within storm drain system structures. Pyrethroid insecticides are among the most used insecticides in urban areas, and trace levels of pyrethroids are known to exert toxicity to aquatic invertebrates. To investigate pyrethroid occurrence and distribution throughout an urban drainage system, samples of water, sediment, algae, and biofilm were collected from catch basins, open channels, and outfalls in Los Angeles County, California, during the dry season. From 3 catch basins, 7 open channels, and 7 outfalls, a total of 28 water samples, 4 sediment samples, 8 algae samples, and 4 biofilm samples were collected and analyzed. Pyrethroid concentrations above the reporting limit were detected in 89% of water samples and all sediment, algae, and biofilm samples, with bifenthrin and cyfluthrin being the most frequently detected compounds. The median total pyrethroid concentrations in water, sediments, algae, and biofilms were 27 ng/L, 88 ng/g, 356 ng/g, and 3556 ng/g, respectively. Bifenthrin concentrations in catch basins were found to be significantly higher than those in open channels or outfalls. Significant correlations were found for various metrics, including between pyrethroid partitioning in water samples and total suspended solids. These findings highlight the role of underground catch basins as a sink as well as a secondary source for contaminants such as pyrethroid insecticides. Prevention of the input of these urban originated contaminants to catch basins is crucial for protecting the water quality of urban surface waters. [Display omitted] • Pyrethroids were detected in water, sediment, algae, and biofilm samples. • Bifenthrin and cyfluthrin were the most frequently detected pyrethroids. • Bifenthrin concentrations in water were highest in catch basins. • Residues were particularly enriched on suspended solids in open channels. • Median toxic units in water were above aquatic invertebrate toxicity benchmarks. [ABSTRACT FROM AUTHOR]

• An original spatio-temporal statistical downscaling procedure was proposed. • An original procedure for modeling extreme rainfall processes over a wide range of spatial and temporal scales. • It is feasible to establish the linkages between GCM climate projections and rainfall extremes at a local site. • A robust procedure for accurate assessment of climate change impacts on local rainfall extremes. • An illustrative application using 21 GCMs and extreme rainfall data for Ontario region was presented. The main challenge in the assessment of climate change impacts on the estimation of extreme rainfalls (ERs) for urban drainage systems design is how to establish the linkages between the climate projections given by Global Climate Models (GCMs) at global scales and the observed extreme rainfalls at a given local site. Downscaling approaches have been proposed in many previous studies to downscale global-scale GCM daily information to regional-scale daily climate projections. However, these daily downscaled data are still considered too coarse in both spatial and temporal resolutions and hence not suitable for climate change impact studies at a local site or for small urban watersheds. The present study proposes therefore an innovative statistical downscaling (SD) approach for establishing the linkage between daily extreme rainfalls at regional scales and daily and sub-daily extreme rainfalls at a local (point) scale. The feasibility and accuracy of the proposed method were assessed for a case study in Ontario (Canada) using observed ER data from seven raingauges and climate simulation outputs from 21 GCMs that have been downscaled by NASA to a regional 25-km scale for the RCP 4.5 scenario. Results based on various graphical and numerical comparison criteria have indicated the feasibility and accuracy of the proposed SD approach. In addition, a robust assessment of the climate change impacts on the ERs for urban drainage system design was performed using a series of statistical tests in sequence to evaluate the significant changes of rainfalls among different time periods. It was found that significant increases by 8% to 18% in extreme design rainfalls of return periods up to T = 25 years, and insignificant increases by 3% to 8% in the 50-year and 100-year design rainfalls for many locations, except for one location with a significant increase of 18%. The confidence intervals were also computed for these estimated design rainfalls with widths varying from 5% to 22%. [ABSTRACT FROM AUTHOR]

Municipal separate storm sewer systems (MS4s) function in urbanized areas to convey flows during both wet weather (i.e., stormwater) and dry weather (i.e., urban runoff as well as subsurface sources of flow) to receiving waters. While urban stormwater is known to contain microbial and chemical pollutants, MS4 dry weather flows, or non-stormwater discharges (NSWDs), are much less studied, although they are also known to contain pollutants, especially when these flows include raw sewage. In addition, some natural NSWDs (e.g., from groundwater infiltrating MS4 pipes) are critical for aquatic habitat protection. Thus, it is important to distinguish NSWD sources to prevent non-natural flows while retaining natural waters (i.e., groundwater). Here, MS4 dry weather flows were assessed by analyzing water samples from MS4 outfalls across multiple watersheds and water provider service areas in south Orange County, CA; potential NSWD sources including sewage, recycled water, potable water, and groundwater were sampled and analyzed for their likely contributions to overall NSWDs. Geochemical and microbiological water quality indicators, as well as bacterial communities, differed across NSWDs, yet water quality within most locations did not vary significantly diurnally or by sampling date. Meanwhile, NSWD source waters had distinctly different bacterial taxa abundances and specific bacterial genera. Shared geochemical and microbial characteristics of certain sources and outfall flows suggested the contributions of sources to outfall flows. The average proportions by sources contributing to MS4 outfalls were further estimated by SourceTracker and FEAST, respectively. The results of this study highlight the use of multiple tools when assessing chemical and microbiological water quality to predict sources of NSWDs contributing to urban MS4 flows during dry weather. This information can be used to support management actions to reduce unnatural and high risk sources of dry weather drainage while preserving natural sources important to environmental health in downstream receiving waters. [Display omitted] • Significantly different water quality across MS4 outfalls and source waters. • Water quality differed across MS4 flows, but not within most locations. • Water quality parameters demonstrated the impacts of source waters on MS4 flows. • Specific bacterial genera associated with source waters. • Proportions predicted by sequencing and some water quality parameters correlated. [ABSTRACT FROM AUTHOR]

Combined Sewer Overflows (CSOs) are the most important source of diffuse contamination in urban environments. Cleaner production in cities necessarily involves the reduction of both frequency and contamination linked to overflows in rain events as well as the control and minimization of its impacts in aquatic ecosystems. That would additionally lead to an increase in waste water treatment plant energy efficiency. However, there is an extended belief among sanitation managers at municipal level that impacts of CSOs in large rivers are not perceptible due to dilution effect. To dismantle this myth, the present article analyses the impacts of CSOs in the Spanish widest river, the Ebro River. The results suggest that the Ebro tends to worsen in dry season during intense rainfall, inviting to perform proper interventions to reduce CSOs along its urban stretch. Image 1 • Combined Sewer Overflows are one of the main pressures on urban water. • Concentration of ammonium is a proper parameter to detect its impacts. • Even in wide rivers as Ebro concentration of ammonium rises due to rain events. • It is urgent to minimize frequency and pollution of Combined Sewer Overflows. [ABSTRACT FROM AUTHOR]

Land-based sources contribute approximately 80% of anthropogenic debris in marine environments. A main pathway is believed to be rivers and storm-water systems, yet this input is rarely quantified. We aimed to quantify the abundance of land-based debris entering a river system through storm drains in an urban area of tropical Australia. To account for seasonal variability, debris was quantified pre, post and during the wet season from 2014 to 2017. Plastic items within the river were compared to those in adjacent parks to assess similarities in debris composition. A total of 27,943 items were collected (92% plastic). Debris loads in the post-wet seasons were significantly higher than the wet-season. Furthermore, variability in the portion of debris found in nearby parks compared to the river suggests that factors other than rainfall, play a role in debris abundance. These results can be used to identify targeted management strategies to reduce debris loads. • A total of 27,943 anthropogenic debris items were collected from a Queensland river over four consecutive years. • There was a consistent input of debris in the river through time, even in years of low rainfall. • The abundance of debris collected during the wet season was unexpectedly lower than that collected in the post-wet seasons. • Debris in different sections of the river appeared to be from different sources depending on the site location. [ABSTRACT FROM AUTHOR]

For the studied alpine peatland in the Altai Mountains, the mean relative contribution of inflow meltwater is up to 76%; moreover, it is a stable source, especially in the early stage of the growing season. By contrast, summer precipitation, which typically occurs as storm events and drains rapidly, only accounts for 24%. There is a co-variation between the external source water δ18O and the Carex pamirensis δ18O cell , suggesting that the δ18O cell faithfully reflect variations of soil/swale water δ18O. Therefore, we conclude that the inflow meltwater is the dominant water source controlling the δ18O cell values, implying that the δ18O p signal of winter half-year precipitation is preserved in the δ18O cell values of C. pamirensis at the study site. • Inflow meltwater is the dominant water source for the studied alpine peatland. • There is a nearly constant net monthly α-cellulose 18O enrichment factor. • The Carex pamirensis δ18O cell faithfully records the δ18O of the source water. • The winter half-year precipitation δ18O signal is preserved in the δ18O cell. Few studies have fully considered how hydrological inputs and climate influence the linkage between the oxygen isotopic composition of α-cellulose (δ18O cell) and their source waters in vascular-plant-dominated alpine peatlands. In this study, in order to test whether δ18O cell can be used as a hydroclimatic indicator, we investigated the relationship between the δ18O values of cellulose extracted from the dominant plant species (Carex pamirensis) and those of potential source waters during two growing seasons (from May to September) in the Sahara sand peatland in the southern Altai Mountains. Concurrently, the Roden–Lin–Ehleringer (RLE) mechanistic model was applied to better understand oxygen isotopic fractionation during cellulose synthesis. We found that the meltwater from snow/ice cover and seasonally-frozen soil played a critical role in controlling the hydrological processes in this alpine peatland. The δ18O values of both swale water and soil water responded more sensitively to variations in inflow meltwater than did summer precipitation. IsoSource modelling demonstrated that the mean 76–24% split between meltwater and summer precipitation inputs determined the overall isotopic composition of the peatland water. The slopes of the peatland water line (6.38) and meltwater line (6.87) were slightly lower than that of the local meteoric water line (LMWL) (7.72), suggesting limited evaporation from these external water sources due to the relatively high humidity (73–80%) in the studied fen. However, the slopes of the stem water line (4.53) and leaf water line (3.57) were generally lower than that of the LMWL, indicating that the internal plant waters have experienced isotopic enrichment during transpiration. Interestingly, the variations of δ18O cell (of shoots, stems and leaves) fall within a relatively narrow range (<±3‰), which is mainly attributed to a nearly constant monthly net 18O enrichment factor (11.13 ± 1.07‰ for Δ Modelled), together with a smoothing effect. Furthermore, empirical correlation and RLE modeling both showed the co-variation of external source water and cellulose synthesis, demonstrating that the cellulose oxygen isotope composition of C. pamirensis can faithfully reflect variations in soil/swale water. These findings strongly suggest that inflow meltwater is the dominant water source in determining δ18O cell , implying that the δ18O p signals of precipitation in the winter half-year (October–April) may be inherited by the δ18O cell values of C. pamirensis at the study site. Therefore, our results provide important insights for the hydroclimatic interpretation of past variations in δ18O cell values in vascular plants in alpine peatlands. [ABSTRACT FROM AUTHOR]

Abstract Winery wastewater generated during vinification is often co-treated with the municipal wastewater at the biological sections of the municipal wastewater treatment plants prior to its discharge into the environment, and the grey water footprint associated with these discharges are often neglected from water footprint assessments of the wine-making process. This study presents a method for assessing the grey water footprint associated with winery wastewater co-treated with the municipal wastewater at municipal wastewater treatment plants. The applicability of this method is illustrated with a case study for the Niagara Region of Ontario, Canada. The total grey water footprint of treated winery wastewater effluents discharged to surface waters was determined to be 1.47 × 107 m3/yr. Co-treatment substantially decreased the grey water footprint compared to that of the untreated winery wastewater (99.3% reduction). However, the co-treated winery wastewater still exerts a substantial grey water footprint equivalent to over 960 times its total average annual volume and should not, therefore, be excluded from a water footprint assessment of wine-making processes. The grey water footprint is very sensitive to changes in the assumed values of background concentration and maximum allowable parameter concentrations in the surface water receiver, and varies significantly for each parameter of concern. Accounting for variations in background concentration of the receiver, Lake Ontario, Canada, between the discharge locations of the individual wastewater treatment plants increased the calculated grey water footprint by an order of magnitude. An understanding of the variations in receiver water quality should be considered as a part of a grey water footprint analysis that combines the footprints of multiple effluent streams. Highlights • Grey water footprint assessments of treated winery wastewater effluents are missing in the literature. • Total grey water footprint of treated WWW discharged into surface water receivers was estimated for Niagara Region, Canada. • Co-treatment of winery wastewaters in municipal WWTPs reduced their grey water footprint. • Treated winery wastewater effluents that meet regulatory requirements still exert a substantial grey water footprint. • The grey water footprint of treated winery wastewater should not be excluded from water footprint assessments. [ABSTRACT FROM AUTHOR]

Highlights • Storm drain module that can be coupled with existing gridded distribute models. • The integrated model is suitable for flash flood forecasting of large urban areas. • The model offers a tool for planning and management of stormwater infrastructure. • A salient feature of the approach is the use of the equivalent storm drain network. Abstract For accurate flash flood forecasting and effective stormwater planning and management in urban areas, it is necessary to model not only the natural channel systems but also the large and complex networks of storm drains. In this work, we describe a modular storm drain model that can easily be coupled with existing gridded distributed hydrologic models for real-time flash flood forecasting, and stormwater planning and management for large urban areas (>100 km2). A salient feature of our approach is the use of the equivalent storm drain network (ESDN) which approximates the actual network on the same grid as that of the distributed hydrologic model, thereby rendering coupling simple and modular. In the integrated model, storm-drain flow occurs through the simplified network coarsened to the resolution of the distributed hydrologic model without full 1D-2D dynamics or very detailed man-made structures and features modeled. The integrated model is applied to a 144.6 km2 area of five urban catchments in the Cities of Arlington and Grand Prairie in Texas, US. Comparisons at selected locations using kinematic-wave flow simulations show that the ESDN approximates the flow through the original network very well with attendant savings in computational amount and reduction in modeling complexities. The impact of the storm drain network is assessed via a combination of simulation experiments, sensitivity analysis and limited comparison with observed flow. It is shown that the storm drain network in highly urbanized catchments in the study area is very effective in reducing surface flow at most locations for about 30 min following onset of significant rainfall, that the existing stormwater infrastructure would lose effectiveness for approximately 30% of the study area with a 15% increase in imperviousness relative to the current conditions, and that significant uncertainties exist in partitioning of surface flow into storm drain and natural channel flows due to sensitivity to inlet flow modeling. With greatly reduced computing cost and modeling complexity, the proposed approach offers a practical solution for integrated stormwater modeling for large urban areas for a wide range of applications. The proposed approach cannot, however, resolve flow at sub-grid scales and hence is not appropriate for very detailed modeling for small areas. [ABSTRACT FROM AUTHOR]

Abstract Onsite runoff control is considered an important part of sustainable urban drainage schemes, but estimating the maximum runoff flow rate from a catchment with onsite runoff controls remains controversial. Runoff controls complicate the issue by dividing the catchment into several subcatchments that feed into individual runoff controls, which dynamically regulate the catchment imperviousness. Rational Method (RM) is the most-employed technique to determine maximum flow rates for designing urban drainage infrastructures, but it cannot handle such conditions. Nonetheless, it has advantages over alternative methods in terms of principle from the urban drainage design perspective. This work develops Rational Method Prime (RMP) that follows the basic principle of RM but instead recalculates catchment variables by taking into account runoff control effects and evaluates runoff control efficiencies by using two indices. RMP has three merits: (1) providing an integrated response of the whole catchment with runoff controls; (2) interpreting runoff control effects by plotting runoff flow rate-rainfall duration curves; (3) connecting the design of runoff controls and storm sewers that are based on different design principles and rainfall statistics. Case study results showed that runoff controls reduced peak flow rates by 5.83–91.6%, corresponding to reduction factors for return period of maximum flow rate from 0.04 to 0.76. Indeed, the original RM is based on four assumptions, which also cause its weakness, and there have been current methods to address 3 of them. RMP contributes to addressing the last assumption (i.e. constant catchment imperviousness), which finally allowing the evolution from RM 1.0 to 2.0. Graphical abstract Image 1 Highlights • RMP estimates runoff peak rate from a catchment with runoff controls. • RMP interprets runoff control effects both separately and in combination. • RMP finally allows the evolution from Rational Method 1.0 to 2.0 • Rational Method 2.0 enables an integrated design of storm sewer and runoff control. [ABSTRACT FROM AUTHOR]

Stormwater contamination can threaten the health of aquatic ecosystems and human exposed to runoff via nutrient and pathogen influxes. In this study, the concentrations of 11 bacterial pathogens and 47 antibiotic resistance genes (ARGs) were determined by using high-throughput microfluidic qPCR (MFQPCR) in several storm drain outfalls (SDOs) during dry and wet weather in Tampa Bay, Florida, USA. Data generated in this study were also compared with the levels of fecal indicator bacteria (FIB) and sewage-associated molecular markers (i.e., Bacteroides HF183 and crAssphage markers) in same SDOs collected in a recent study ( Ahmed et al., 2018 ). Concentration of FIB, sewage-associated markers, bacterial pathogens and many ARGs in water samples were relatively high and SDOs may be potentially hotspots for microbial contamination in Tampa Bay. Mean concentrations of culturable E. coli and Enterococcus spp. were tenfold higher in wet compared to dry weather. The majority of microbiological contaminants followed this trend. E. coli eaeA , encoding the virulence factor intimin, was correlated with levels of 20 ARGs, and was more frequently detected in wet weather than dry weather samples. The bla KPC gene associated with carbapenem resistant Enterobacteriaceae and the beta-lactam resistant gene ( bla NPS ) were only detected in wet weather samples. Frequency of integron genes Intl2 and Intl3 detection increased by 42% in wet weather samples. Culturable E. coli and Enterococcus spp. significantly correlated with 19 of 47 (40%) ARG tested. Sewage-associated markers crAssphage and HF183 significantly correlated ( p  < 0.05) with the following ARGs: intl1 , sul1 , tet (M), ampC , mexB , and tet (W). The presence of sewage-associated marker genes along with ARGs associated with sewage suggested that aging sewage infrastructure contributed to contaminant loading in the Bay. Further research should focus on collecting spatial and temporal data on the microbiological contaminants especially viruses in SDOs. [ABSTRACT FROM AUTHOR]

In recent years, the Chinese government has strengthened its efforts in surface water protection and restoration through strict policies and heavy investments. A clear understanding of the impacts of land use on water quality is necessary in order to ensure an effective and efficient implementation of the ongoing surface water restoration program in China. To this end, four small watersheds (less than 5000 ha) in southeastern China, which have clear gradients in the intensities of agriculture (17.0–45.4%), forest (35.2–73.6%) and built-up area (3.3–8.5%), were investigated regarding the impacts of land use on water quality. In addition to the general water quality indices, characteristic components derived by fluorescence excitation-emission matrices (FEEMs) coupled with parallel factor analysis (PARAFAC) were employed to explore a more accurate association between land use and water quality. The results show that agricultural intensity has significant effects by elevating the concentrations of dissolved organic carbon (DOC, an approximate six-fold increase) and total phosphorous (TP, an approximate four-fold increase) in the surface waters. A total of five PARAFAC components representing terrestrial (three components) and protein-like (two components) substances were identified. The PARAFAC results indicate that land-use patterns affected the dissolved organic matter (DOM) in the aspects of both amount and composition. The intensity (R.U.) of the terrestrial components showed a strong correlation (r 2  = 0.95, p  = 0.01) with agricultural land percentage. Moreover, although the proportion of built-up area varies with a relatively small range, a protein-like component could predict its impact with excellent sensitivity (r 2  = 0.94, p  = 0.02), whereas the general water quality indices were incapable of predicting the impact due to their multiple sources. The results of this study demonstrate that the FEEMs-PARAFAC technique provides an inexpensive and effective tool for policy makers to overcome the insensitivity of general water quality indices, particularly for the restoration of watersheds with complex land-use patterns. [ABSTRACT FROM AUTHOR]

Groundwater and surface water are often closely coupled and are both under the influence of multiple stressors. Stressed groundwater systems may lead to a poor ecological status of surface waters but to date no conceptual framework to analyse linked multi-stressed groundwater – surface water systems has been developed. In this paper, a framework is proposed showing the effect of groundwater on surface waters in multiple stressed systems. This framework will be illustrated by applying it to four European catchments, the Odense, Denmark, the Regge and Dinkel, Netherlands, and the Thames, UK, and by assessing its utility in analysing the propagation or buffering of multi-stressors through groundwater to surface waters in these catchments. It is shown that groundwater affects surface water flow, nutrients and temperature, and can both propagate stressors towards surface waters and buffer the effect of stressors in space and time. The effect of groundwater on drivers and states depends on catchment characteristics, stressor combinations, scale and management practises. The proposed framework shows how groundwater in lowland catchments acts as a bridge between stressors and their effects within surface waters. It shows water managers how their management areas might be influenced by groundwater, and helps them to include this important, but often overlooked part of the water cycle in their basin management plans. The analysis of the study catchments also revealed a lack of data on the temperature of both groundwater and surface water, while it is an important parameter considering future climate warming. [ABSTRACT FROM AUTHOR]

Water sensitive interventions are being promoted to reduce the adverse impacts of urban development on natural water cycles. However it is currently difficult to know the best strategy for their implementation because current and desired urban water performance is not well quantified. This is particularly at the city-region scale, which is important for strategic urban planning. This work aimed to fill this gap by quantifying the water performance of urban systems within city-regions using ‘urban water metabolism’ evaluation, to inform decisions about water sensitive interventions. To do this we adapted an existing evaluation framework with new methods. In particular, we used land use data for defining system boundaries, and for estimating natural hydrological flows. The criteria for gauging the water performance were water efficiency (in terms of water extracted externally) and hydrological performance (how much natural hydrological flows have changed relative to a nominated pre-urbanised state). We compared these performance criteria for urban systems within three Australian city-regions (South East Queensland, Melbourne and Perth metropolitan areas), under current conditions, and after implementation of example water sensitive interventions (demand management, rainwater/stormwater harvesting, wastewater recycling and increasing perviousness). The respective water efficiencies were found to be 79, 90 and 133 kL/capita/yr. In relation to hydrological performance, stormwater runoff relative to pre-urbanised flows was of most note, estimated to be 2-, 6- and 3- fold, respectively. The estimated performance benefits from water sensitive interventions suggested different priorities for each region, and that combined implementation of a range of interventions may be necessary to make substantive gains in performance. We concluded that the framework is suited to initial screening of the type and scale of water sensitive interventions needed to achieve desired water performance objectives. [ABSTRACT FROM AUTHOR]

CrAssphage are recently-discovered DNA bacteriophages that are prevalent and abundant in human feces and sewage. We assessed the performance characteristics of a crAssphage quantitative PCR (qPCR) assay for quantifying sewage impacts in stormwater and surface water in subtropical Tampa, Florida. The mean concentrations of crAssphage in untreated sewage ranged from 9.08 to 9.98 log 10 gene copies/L. Specificity was 0.927 against 83 non-human fecal reference samples and the sensitivity was 1.0. Cross-reactivity was observed in DNA extracted from soiled poultry litter but the concentrations were substantially lower than untreated sewage. The presence of the crAssphage marker was monitored in water samples from storm drain outfalls during dry and wet weather conditions in Tampa, Florida. In dry weather conditions, 41.6% of storm drain outfalls samples were positive for the crAssphage marker and the concentrations ranged from 3.60 to 4.65 log 10 gene copies/L of water. After a significant rain event, 66.6% of stormwater outlet samples were positive for the crAssphage marker and the concentration ranged from 3.62 to 4.91 log 10 gene copies/L of water. The presence of the most commonly used Bacteroides HF183 marker in storm drain outfalls was also tested along with the crAssphage. Thirteen samples (55%) were either positive (i.e., both markers were present) or negative (i.e., both markers were absent) for both the markers. Due to the observed cross-reactivity of this marker with DNA extracted from poultry litter samples, it is recommended that this marker should be used in conjunction with additional markers such as HF183. Our data indicate that the crAssphage marker is highly sensitive to sewage, is adequately specific, and will be a valuable addition to the MST toolbox. [ABSTRACT FROM AUTHOR]

Leptospirosis has emerged as an important urban health problem as slum settlements have expanded worldwide. Yet the dynamics of the environmentally transmitted Leptospira pathogen has not been well characterized in these settings. We used a stratified dense sampling scheme to study the dynamics of Leptospira abundance in surface waters from a Brazilian urban slum community. We collected surface water samples during the dry, intermediate and rainy seasons within a seven-month period and quantified pathogenic Leptospira by quantitative PCR (qPCR). We used logistic and linear mixed models to identify factors that explained variation for the presence and concentration of Leptospira DNA. Among 335 sewage and 250 standing water samples, Leptospira DNA were detected in 36% and 34%, respectively. Among the 236 samples with positive results geometric mean Leptospira concentrations were 152 GEq/mL. The probability of finding Leptospira DNA was higher in sewage samples collected during the rainy season when increased leptospirosis incidence occurred, than during the dry season (47.2% vs 12.5%, respectively, p = 0.0002). There was a marked spatial and temporal heterogeneity in Leptospira DNA distribution, for which type of water, elevation, and time of day that samples were collected, in addition to season, were significant predictors. Together, these findings indicate that Leptospira are ubiquitous in the slum environment and that the water-related risk to which inhabitants are exposed is low. Seasonal increases in Leptospira presence may explain the timing of leptospirosis outbreaks. Effective prevention will need to consider the spatial and temporal dynamics of pathogenic Leptospira in surface waters to reduce the burden of the disease. [ABSTRACT FROM AUTHOR]

In recent years, urban pluvial flooding caused by extreme rainfall has increasingly occurred across China. This paper reviews the challenges faced by China in addressing urban pluvial flooding and managing urban stormwater, with a particular focus on a policy initiative termed sponge cities . The paper first synthetically presents pluvial flood disasters in urbanized areas, and analyses their causes and formation mechanisms. It then introduces China’s sponge cities initiative and discusses policy implementation in relation to contemporary understanding of sustainable urban stormwater management and international experience with innovative practices. The initiative, while theoretically well grounded and appropriate by its design principles, is shown subject to diverse implementation challenges, ranging from technological complexity to limited or lack of governance capacity as reflected in management ideology, knowledge and capacity of learning, participatory and integrated governance, investment financing, implementation pathway, planning and organization, and project evaluation. The paper offers some strategies for addressing those challenges, which include: 1) continuous experiment-based deep learning through pilot and institutionalization of knowledge and information management with city-to-city peering learning mechanisms, 2) establishment of institutional mechanisms dedicated to participatory, coordinated and integrated governance of the policy initiative, 3) increased government role in creating favorable conditions for investments, and 4) appropriate planning and an adaptive approach to policy implementation. The paper concludes that the sponge cities initiative can be an effective approach only if China commits to appropriate technical, governance, financial, and organizational measures to effectively address the challenges for policy implementation. [ABSTRACT FROM AUTHOR]

The activation of available in-sewer storage volume has been suggested as a low-cost flood and combined sewer overflow mitigation measure. However, it is currently unknown what the attributes for suitable objective functions to identify the best location for flow control devices are and the impact of those attributes on the results. In this study, we present a novel location model and efficient algorithm to identify the best location(s) to install flow limiters. The model is a screening tool that does not require hydraulic simulations but rather considers steady state instead of simplistic static flow conditions. It also maximises in-sewer storage according to different reward functions that also considers the potential impact of flow control device failure. We demonstrate its usefulness on two real sewer networks, for which an in-sewer storage potential of approximately 2,000 m 3 and 500 m 3 was estimated with five flow control devices installed. [ABSTRACT FROM AUTHOR]

Bucharest, a city of about 1.9 million inhabitants and covering a surface of about 228 km 2 , faces two main hydrogeological problems. Both are results of the interaction between the aquifer system and the underground infrastructure. The first problem consists in the barrier effect produced by the extensively channelized Dambovita River that cuts Bucharest city in two parts, increasing consequently the groundwater hydraulic heads. The second problem is actually a twofold concern and it is due to the strong hydraulic interaction between the sewer system and the groundwater. As consequence, the seepage into the sewer network increases the wastewater flow rates. Restoration of its conduits triggers consequently the hydraulic heads increase in several residential areas of the city. A Bucharest city urban hydrogeology project has been built, it’s primary milestone being the urban groundwater numerical flow model. This focuses on the interaction between the urban infrastructure and the groundwater system. The resulted hydrological water balance outlined that, for the entire Bucharest sewer network, about 0.92 m 3 /s wastewater surplus originates from the groundwater seepage. It has been also determined that about 16.9km (3.5%) of the sewer network is completely immersed into the groundwater and about 79.8km (16.5%) is partially immersed. The urban hydrogeological model framework is currently used to carry out distinct hydrogeological studies related to the city sewer system rehabilitation, infrastructure developments, groundwater protection, and environmental impact. The feedback from these studies increase further the city scale model knowledge and accuracy. A direct hydraulic connection between the surface water and the groundwater has been systematically confirmed. [ABSTRACT FROM AUTHOR]

Groundwaters from basement aquifers in the Ochi-Narkwa basin of the Central Region together with rain and surface waters have been analysed for stable isotopes (δ 18 O, δ 2 H and δ 13 C) and radioisotopes ( 3 H and 14 C) to determine sources of recharge, groundwater residence time and flow path. The mechanism of recharge to the groundwaters is by direct infiltration of past local rainfall of mean isotopic composition δ 18 O = −3.8‰ V-SMOW and δ 2 H = −18‰ V-SMOW. Tritium in the groundwaters ranged from 0.05 ± 0.07 to 4.75 ± 0.16 TU. Tritium data revealed that 85% of the groundwater samples were of modern recharge or young waters. The 14 C content of the groundwaters ranged between 9.50 pMC in borehole CR2-50 at Ekumfi Asokwa to 113.56 pMC in borehole CR3-26 at Onyaadze. Evaluation of 3 H and 14 C data distinguished three groups of water namely (1) waters characterised by high 3 H and high 14 C depicting modern recharge, (2) waters showing a mixture of young and old water due to fractures and (3) waters showing low 3 H and low 14 C contents referred to as very old waters and include borehole CR2-50 at Ekumfi Asokwa. The estimated age or residence time of this older water is 19,459 years BP based on uncorrected age. The major flow direction is northwest-southeast. The dominant months contributing to recharge in the study area were February, March, April, May, June, August, September and October. Groundwater residence times in the basement aquifers of the Ochi-Narkwa basin showed that groundwater abstraction is sustainable and requires that the recharge areas are protected from contamination. [ABSTRACT FROM AUTHOR]

The outbreak of COVID-19 led to restrictions on movements and activities, which presented a serious challenge to the resilience of the water sector. It is essential to understand how successfully water companies responded to this unprecedented event so effective plans can be built for future disruptive events. This study aimed to evaluate how the water sectors in the UK and Ireland were affected from a holistic sustainability and resilience-based perspective. Using pre-COVID data for 18 indicators of company performance and comparing them to the first year of the pandemic, the direction and magnitudes of change varied across companies. Financial indicators were significantly negatively affected, with interest cover ratio , post-tax return on regulated equity , and operating profit , exhibiting the greatest average declines of 21%, 21%, and 18%, respectively, a trend that would be dangerous to provisions and company operations if continued. Despite this, service and environmental indicators improved during the first year of the pandemic, exemplified by unplanned outage , risk of sewer storm flooding , and water quality compliance risk decreasing by a mean average of 37%, 32%, and 27%, respectively. Analysis using the Hicks-Moorsteen Productivity Index concluded that average productivity increased by 35%. The results suggest that the water sector was relatively resilient to the COVID-19 pandemic in terms of services, but adverse effects may have manifested in a deteriorated financial position that could exacerbate future challenges arising from exogenous pressures such as climate change. Specific advice for the UK water sector is to scrutinize non-critical spending, such as shareholder payments, during periods of economic downturn to ensure essential capital projects can be carried out. Although results are temporal and indicator selection sensitive, we recommend that policy, regulation, and corporate culture embrace frameworks that support long-term resilience to since the relative success in response to COVID-19 does not guarantee future success against differing challenges. This study generates a timely yet tentative insight into the diverse performance of the water sector during the pandemic, pertinent to the water industry, regulators, academia, and the public. • 18 indicators covering all aspects of sustainability for 19 companies utilised. • Financial indicators were significantly negatively affected. • Service and environmental indicators improved. • Productivity analysis concluded that average productivity increased by 35. • Initial impressions suggest water was relatively resilient in the short-term. [ABSTRACT FROM AUTHOR]

• In fingerprinting method sampling from only the influent of a WWTP is required. • Fingerprinting method is based on the rain proportion in a sample and a mass balance. • Drugs like painkillers are suitable tracers for estimating the rain proportion. The ecological state of receiving water bodies can be significantly influenced by organic micropollutants that are emitted via stormwater runoff. Reported efforts to quantify the emission of micropollutants mainly focus on sampling at combined sewer overflows and storm sewer outfalls, which can be challenging. An alternative method, called fingerprinting, was developed and tested in this study. The fingerprinting method utilizes wastewater treatment plant (WWTP) influent samples and derives the proportion of stormwater in a sample. This is achieved by comparing the wet weather vs dry weather concentrations of substances-tracers which are present only in wastewater. It is then possible to estimate the concentration of organic micropollutants in stormwater runoff from measurements in the influent of a WWTP based on a mass balance. In this research, the fingerprinting method was applied in influent samples obtained in five WWTPs in the Netherlands. In total, 28 DWF and 22 WWF samples were used. The chosen tracers were ibuprofen, 2-hydroxyibuprofen, naproxen and diclofenac. Subsequently, the concentration in stormwater runoff of 403 organic micropollutants was estimated via the WWF samples. The substances that were present and analyzed included glyphosate and AMPA, 24 out of 254 pesticides, 6 out of 28 organochlorine pesticides, 45 out of 63 pharmaceuticals, 15 out of 15 PAHs, 2 of the 7 PCBs, and 20 of 33 other substances (e.g. bisphenol-A). A comparison with findings from other studies suggested that the fingerprinting method yields trustworthy results. It was also noted that a representative and stable dry weather flow reference concentration is a strict requirement for the successful application of the proposed method. [Display omitted] [ABSTRACT FROM AUTHOR]

The stream-aquifer interface is considered a hotspot for environmental and ecological issues. Due to their complexity, the exchange mechanisms occurring between groundwater and surface water at this interface are not yet fully understood. Many studies have focused on the characterization of the two-dimensional distribution of an artificial tracer (generally injected into the stream) within and outside the streambed, but there is insufficient information about the 3D spatial distribution of the tracer fluxes and their temporal variations. We monitored the transport of an artificial solute tracer transport with 3D electrical resistivity tomography (ERT) in order to improve the 3D spatial resolution in the imaging of the first tens of centimeters of streambed sediments and propose an innovative approach of the three-dimensional and temporal observation of the water fluxes. The hydro-geophysical field measurements were made on a small stream located within the Orgeval watershed (Seine et Marne, France). Using a resistivimeter connected to 180 electrodes, 3D electrical resistivity tomograms were made on a riverbed section, as a brine tracer was injected directly into the hyporheic zone. Before the tracer monitoring, the static 3D resistivity tomograms were consistent with the lithological heterogeneities identified at the site. However, this study defines some prerequisites to high-resolution 3D underwater resistivity measurements: for instance, a precise knowledge of an eventual weak electrode contact and a spatial resolution identical in every spatial direction. First results show a rapid development and persistence of a conductive plume around the injection point which disappears progressively after the injection. Within the sediments top layer, preferential flowpaths were highlighted due to the highly heterogeneous medium and hydraulic conductivity. The riverbed topography showed some pool-riffle sequences which conduct the formation of local entering and exiting zones. It seems clear that riverbed heterogeneities drive some local exchanges between surface water and pore water, despite the gaining condition of the stream. Moreover, inversion and data processing appear very sensitive to the boundary condition variations, such as the thickness and the resistivity of the water layer. This makes a quantitative interpretation of tracer fluxes within the hyporheic zone difficult. We demonstrate that for this type of study, knowledge of these conditions and precise monitoring of their fluctuations in time are required. [ABSTRACT FROM AUTHOR]

Natural dissolved organic matter (NDOM) in surface waters has a high sorption affinity for TiO 2 during long contact. An attached NDOM layer can act as a conduction band electron and/or valance band hole acceptor, and NDOM can also decrease the concentration of hydroxyl radicals ( OH) in the bulk phase. Therefore, the degradation kinetics and mechanism for degradation of acetaminophen on NDOM capped TiO 2 (NDOM-TiO 2 ) are significantly different from those on raw TiO 2 . Quantum calculation results suggest that hydroxylation to the ortho position in relation to the acetamide group is more favorable. Although OH induced hydroxylation is the predominant pathway for degradation of acetaminophen on TiO 2 , one-electron oxidation of acetaminophen by a valance band hole, excited triplet NDOM or NDOM radical cation is the major degradation pathway on NDOM-TiO 2 . This study is the first to detect and confirm APAP oligomers as intermediates during the degradation of acetaminophen by TiO 2 photocatalysis, especially when using NDOM-TiO 2 as a catalyst. The results suggest the reactivity of TiO 2 could change significantly after long exposure to natural water, which need to be concerned about for removal of micropollutants in surface water by TiO 2 photocatalysis. [ABSTRACT FROM AUTHOR]

Microplastics are ubiquitous and affect all environments, including rivers. In recent years the number of studies about microplastics in rivers has strongly increased. But still many questions exist regarding sources, pathways, and the role of land use patterns. In this study the relationship between microplastics abundance and anthropogenic factors (population density, urbanization, land use types), as well as the potential role of storm sewers as pathways in tributaries of the Wu River in Taichung, central Taiwan, were studied. Two river catchments of the Dali River were studied in greater detail to investigate the influence of land use on microplastics abundance along an urban-rural gradient, and to observe the change of microplastics abundance in the transition from rural to urban areas. Samples were taken from 41 different locations in urban and rural areas using a manta net with a mesh size of 0.3 mm. Results show abundances ranging from 0 pcs/m³ in unpopulated rural areas up to 230 pcs/m³ in densely populated urban centers, and are positively correlated with population density. Remarkably, a sharp increase in microplastics abundance was observed at the transition from rural to urban areas, which coincides with the appearance of storm sewers. Land use analysis revealed that microplastics abundance positively correlates with the size of industrial, residential and traffic areas in the catchment areas, and negatively correlates with the size of forest areas. Source areas for microplastics in the studied rivers are likely residential and commercial areas. Furthermore, the results of this study show that correlations between microplastics abundances and population density or land use patterns along urban-rural gradients are not trivial. Strength of correlations can depend on local factors or how well urban-rural gradients are developed. Absence of correlations need to be considered carefully, as existing correlations might be masked by the above-mentioned factors. [Display omitted] • Microplastics pollution suddenly rises at the transition from rural to urban areas. • The majority of microplastics are generated in residential and industrial areas. • Storm sewers are important pathways of microplastics from land into urban rivers. • Strength of correlations depend on development of urban-rural gradients. [ABSTRACT FROM AUTHOR]

The drinking water sources of many cities in southern China are frequently contaminated by upstream urban drainage during storm events, which brings high concentrations of N -nitrosamine (NA) precursors and poses a threat to the safety of drinking water. We conducted two sampling campaigns during the heavy rain season in 2015 in one representative city in southern China. We detected that the concentration of N -nitrosodimethylamine formation potential (NDMA FP) in urban drainage during two storm events was 80–115 ng/L and the total formation potential concentration of nine nitrosamines (TNA 9 FP) was 145–165 ng/L. To address the deteriorated water quality, 30 mg/L of powdered activated carbon (PAC) was fed into the water intake. PAC adsorption alone could remove 52% of NDMA FP and 52% of TNA FP, while the subsequent conventional process only removed 8% of TNA FP. We isolated six chemicals ( N,N -benzyldimethylamine, 5-[(dimethylamino)methyl]-2-furanmethanol, N,N -dimethyl-3-aminophenol, N,N -dimethylethylamine, Ziram, and N,N -dimethylaniline) and confirmed them to be NA precursors. Among these NA precursors, Ziram was identified for the first time as a NA precursor that is formed via chloramination; its molar yield for NDMA was 6.73 ± 0.40%. [ABSTRACT FROM AUTHOR]

The presence of microplastics (MPs) in freshwater systems that receive discharge of urban effluent implies a great environmental impact. In order to be able to generate proposals that solve this problem, it is necessary to know in detail the contributions of different MPs sources. The aim of this work was to study the contribution of urban sewage discharge to MPs pollution in a stream that runs through a medium-sized city. The spatial distribution of MPs with sizes between 100 μm and 1.5 mm present in surface water was measured and their characteristics, dimensions, shapes and identification were determined. Physical-chemical parameters of the stream water were measured, and a decrease in water quality was found due to wastewater treatment plants. The main source of MPs was effluent from the plants (97% of the total MPs), while the rest came from storm drains and discharge of tributaries. The maximum concentration of MPs found was around 72,000 MP/L (equivalent to 53 million MPs/s), at a point after discharge from both plants. Around 70% of MPs correspond to microfibers with a mean length of around 300 μm and a mean width of around 15 μm, and they are mainly polyethylene fibers. The remaining 30% of MPs are particles with lengths of around 140 μm. The transport of MPs between a point located after discharge of the plants and another point located about 3 km further on was studied, and no significant variation was found in the concentration of MPs. Electrical conductivity was used as a conservative tracer of MPs concentration. This work presents for the first time a detailed analysis of different contributions of MPs to a freshwater system in South America, which receives discharge of wastewater treatment plants, evidencing its important role in pollution. [Display omitted] • The main source of microplastics was effluent from wastewater treatment plants. • About 70% of microplastics found in the stream correspond to microfibers. • Microfibers have a mean length of around 300 μm. • No significant microplastic retention was found in the stream. [ABSTRACT FROM AUTHOR]

[Display omitted] • Isotope monitoring in Berlin during the 2018 – 2020 drought. • Large-scale hydroclimate dynamics determine isotope patterns in the Spree. • Berlin's green spaces largely disconnected from surface waters. • Catchment- & city-scale measures needed to adapt water resources to climate change. Sustainably meeting the growing water demand of cities during a changing climate will be a major challenge in the near future. Adjusting water management strategies towards preserving urban water resources while best utilizing urban "blue" and "green" infrastructure will require precise knowledge of urban water cycling, storage and losses across large built-up areas. To gain this understanding, using stable isotopes of water as tracers in the hydrological cycle can provide valuable insights, but their application remains challenging in complex and heterogeneous metropolitan areas. This study used stable isotopes, combined with hydrometric and climatic data, to assess the imprint of the urban area and climate warming on a large urbanised river system, the River Spree in Berlin, Germany, during the exceptionally warm and dry 2018 – 2020 period. Isotope dynamics in the Spree reflected gradually varying seasonal patterns with more enriched values in summer and more depleted values in winter. Large-scale climate variability and evaporative losses in the upstream catchment, along with anthropogenic activities, impacted isotope and discharge dynamics in the Spree, especially during warm and dry summer and autumn periods. In local urban sub-catchments, variability of isotope dynamics and subsequent water ages and transit times were largely affected by engineered system components, i.e. catchment imperviousness, connectivity to storm drains and effluent discharge. Berlin's green spaces were largely disconnected from surface waters. Urban trees in particular had high water demands during dry periods that may be hard to sustain, as trees showed slower replenishment of soil moisture during winter, resulting in shorter recharge periods under trees. More research will be needed on: (a) how planting design with alternations of urban grassland, shrub and trees can enhance infiltration and maintain water demands for trees during drought; and (b) on better quantifying open-water evaporation in the upstream catchment to fully account for catchment water losses. To sustainably manage and preserve not just Berlin's but also similar cities' water resources in the future, our results indicate that both integrated city- and catchment-scale measures will be necessary. [ABSTRACT FROM AUTHOR]

Carbon cycling in inland waters has been identified as an important, but poorly constrained component of the global carbon cycle. In this study, we compile and analyze particulate organic carbon (POC) concentration data from 1145 U.S. Geological Survey (USGS) gauge stations to investigate the spatial variability and environmental controls of POC concentration. We observe substantial spatial variability in POC concentration (1.43 ± 2.56 mg C/L, mean ± one standard deviation), with the Upper Mississippi River basin and the Piedmont region in the eastern U.S. having the highest POC concentration. Further, we employ generalized linear models (GLMs) to analyze the impacts of sediment transport and algae growth as well as twenty-one other environmental factors on the POC variability. Suspended sediment and chlorophyll- a explain 26% and 17% of the variability in POC concentration, respectively. At the national level, the twenty-one environmental factors combined can explain ca. 40% of the spatial variance in POC concentration. At the national scale, urban area and soil clay content show significant negative correlations with POC concentration, whereas soil water content and soil bulk density correlate positively with POC. In addition, total phosphorus concentration and dam density correlate positively with POC concentration. Furthermore, regional scale analyses reveal substantial variation in environmental controls of POC concentration across eighteen major water resource regions in the U.S. The POC concentration and associated environmental controls also vary non-monotonically from headwaters to large rivers. These findings indicate complex interactions among multiple factors in regulating POC concentration over different spatial scales and across various sections of the river networks. This complexity, together with the large unexplained uncertainty, highlights the need for considering non-linear interplays of multiple environmental factors and developing appropriate methodologies to track the transformation and transport of POC along the terrestrial-aquatic interfaces. [ABSTRACT FROM AUTHOR]

Summary The uncertainty associated with discharge measurement in storm sewer systems is of fundamental importance for hydrologic/hydraulic model calibration and pollutant load estimation, although it is difficult to determine as field benchmarks are generally impractical. This study benchmarks discharge uncertainty in several commonly used sensors by laboratory flume testing with and without a woody debris model. The sensors are then installed in a field location where laboratory benchmarked uncertainty is applied to field measurements. Combined depth and velocity uncertainty from the laboratory ranged from ±0.207–0.710 in., and ±0.176–0.631 fps respectively, and when propagated and applied to discharge estimation in the field, resulted in field discharge uncertainties of between 13% and 256% of the observation. Average daily volume calculation based on these observations had uncertainties of between 58% and 99% of the estimated value, and the uncertainty bounds of storm flow volume and peak flow for nine storm events constituted between 31–84%, and 13–48% of the estimated value respectively. Subsequently, the implications of these observational uncertainties for stormwater best-management practice evaluation, hydrologic modeling, and Total Maximum Daily Load development are considered. [ABSTRACT FROM AUTHOR]

Inappropriate non-storm water entries into the storm drains and the resulting direct discharge into the natural environment on dry-weather days, is a challenging environmental issue in the cities worldwide. To make a preliminary evaluation of non-storm water entry situations, this study presented an approach for source apportionment of non-storm water entries into storm drains based on marker species and a chemical mass balance (CMB) model using a Monte Carlo statistical simulation. Compared with deterministic approaches, this method is capable of accounting for the measurement errors and the impact of variability of the source marker profiles resulting from heterogeneities and therefore presents the most likely range of estimated source contributions. This method was verified using measured data in a catchment in Shanghai, China, covering 374 ha. Here, inappropriate entries of sanitary wastewater, semiconductor wastewater, and groundwater into storm drains can be identified using acesulfame and citric acid, chloride, fluoride and sulfate, and total hardness, respectively, as markers. Using the measured marker profiles, the apportioned source flows were estimated with high precision in comparison to the investigated data, with a relative error less than 11%. Apportioned data revealed strong sanitary source connections to storm drains (i.e., 45.8% of the total sewage output), which were mainly from old residential communities with direct sewer connections to the storm pipes. Additionally, it revealed illicit semiconductor wastewater discharge contributed to 75% of the fluoride load, 52% of the sulfate load, and 32% of the chloride load, despite its low flow component of 9.2%. Therefore, a primary correction strategy of applying end-of-storm pipe control treatment, as well as reconnecting industrial source to the sewer network, was presented. Moreover, the marker library data associated with a variety of source types is expected to provide clear evidence for various non-storm water entry situations in future studies. [ABSTRACT FROM AUTHOR]

The occurrence of 45 PCBs was studied in a wastewater treatment plant (WWTP), which treats industrial wastewater from the zone of Porto Marghera (Venice, Italy) in an MBR, and in the Naviglio del Brenta River, which serves as a source of process water supply for this industrial zone. The focus of the study was placed on the comparison of levels of contamination of the WWTP effluent and the river water by selected PCBs in order to understand the major source of PCB pollution for the Lagoon of Venice and contrast them with the current legislation. Out of 45, 31 PCBs were detected in the WWTP at total median PCB concentration of 5.5 ng/L with a predominant presence of six indicator – PCBs (PCB 28, 52, 101, 138, 153 and 180), which accounted for 50–55% of total PCBs in both wastewater and sludge samples. The total PCB concentration was reduced by around 90% during the applied wastewater treatment to a median concentration of 0.5 ng/L at the WWTP effluent. In the samples collected from the river, 27 PCBs were detected at total median concentration of 2.1 ng/L, which is few times higher than the total PCB concentration found in the WWTP effluent. This result suggests that the current legislative limitations applied to the WWTPs effluent discharges into the Lagoon of Venice, regarding the presence of PCBs (i.e. absent) is rather arbitrary given the higher concentration levels encountered in river water than in the WWTP effluent of the studied industrial WWTP. [ABSTRACT FROM AUTHOR]

[Display omitted] • Four-year monitoring hydrologic changes in four sewersheds within Columbus, OH USA. • Paired watershed approach to assess impacts of green infrastructure (GI) retrofits. • Reductions in peak flow rates, increases in lag-to-peak following GI implementation. • Additional improvements to infrastructure increased inflows, countering GI benefits. Cities across the world are implementing green infrastructure (GI) retrofits to manage stormwater, but limited research has been performed to quantify the hydrologic impact of these efforts at the watershed-scale. To fill this knowledge gap, this study aimed to monitor and evaluate the impact of GI stormwater control measures (SCMs) on sewershed-scale runoff hydrology across multiple treatment sewersheds with varying GI implementation. A paired watershed approach was applied in which a control (i.e., no GI), and three treatment sewersheds (208 bioretention cells and 8,400 m2 of permeable pavement in total) were monitored from 2016 to 2019 in Columbus, Ohio, USA. Further infrastructure changes, such as lining sanitary sewer laterals to prevent infiltration and inflow of stormwater, were anticipated to counterbalance the hydrologic improvements provided by the GI retrofits by routing more stormwater to the storm sewers. Significant decreases in runoff depths and peak flow rates (35–62% and 40–58% respectively) and increases in lag-to-peak (6–64%) were observed in the treatment sewersheds following the installation of GI retrofits. Compared to the control sewershed, the treatment sewersheds had slight increases (1–3 mm) in runoff thresholds and lower runoff coefficients post-GI. Following additional infrastructure changes, increases in volume and rate of flows were observed, but hydrologic indicators did not significantly differ from pre-GI levels (i.e., no net impact of the overall project on runoff hydrology). These responses indicated that sewershed-scale GI implementation successfully mitigated peak flow rates; however, the additional infrastructure improvement projects appear to have neutralized volume reductions by routing additional stormwater to the GI. Results confirm the impacts of sewershed-scale GI retrofits; however, research investigating the optimization of GI retrofit location, climate change impacts, and GI design, construction, and maintenance to maximize benefits of distributed SCMs in urban areas should be further explored. [ABSTRACT FROM AUTHOR]

In urban areas served by separate sewerage consisting of separate pipe systems it is not uncommon for misconnections to be made either accidentally or deliberately, whereby the wrong effluent is connected to the wrong sewer. The main focus of this problem has been on in-household appliances that are wrongly connected to separate surface water sewers, potentially leading to pollution of receiving waters and non-compliance with statutory water quality standards. This paper examines the available evidence to evaluate the potential scale, severity and cost of the problem in England and Wales in comparison to that reported from investigations in the United States. The particular difficulties associated with distinguishing specific sewage sources in the wastewater “cocktail” discharged at polluted surface water outfalls are reviewed. The deficiencies of existing legislation and enforcing compliance with respect to misconnections are also discussed and the pollution potential resulting from domestic misconnections is explored based on sampled data. [ABSTRACT FROM AUTHOR]

Summary In this study, we developed a novel approach to simulate dynamic flow interactions between storm sewers and overland surface for different land covers in urban areas. The proposed approach couples the one-dimensional (1D) sewer flow model (SFM) and the two-dimensional (2D) overland flow model (OFM) with different techniques depending on the land cover type of the study areas. For roads, pavements, plazas, and so forth where rainfall becomes surface runoff before entering the sewer system, the rainfall–runoff process is simulated directly in the 2D OFM, and the runoff is drained to the sewer network via inlets, which is regarded as the input to 1D SFM. For green areas on which rainfall falls into the permeable ground surface and the generated direct runoff traverses terrain, the deduction rate is applied to the rainfall for reflecting the soil infiltration in the 2D OFM. For flat building roofs with drainage facilities allowing rainfall to drain directly from the roof to sewer networks, the rainfall–runoff process is simulated using the hydrological module in the 1D SFM where no rainfall is applied to these areas in the 2D OFM. The 1D SFM is used for hydraulic simulations in the sewer network. Where the flow in the drainage network exceeds its capacity, a surcharge occurs and water may spill onto the ground surface if the pressure head in a manhole exceeds the ground elevation. The overflow discharge from the sewer system is calculated by the 1D SFM and considered a point source in the 2D OFM. The overland flow will return into the sewer network when it reaches an inlet that connects to an un-surcharged manhole. In this case, the inlet is considered as a point sink in the 2D OFM and an inflow to a manhole in the 1D SFM. The proposed approach was compared to other five urban flood modelling techniques with four rainfall events that had previously recorded inundation areas. The merits and drawbacks of each modelling technique were compared and discussed. Based on the simulated results, the proposed approach was found to simulate floodings closer to the survey records than other approaches because the physical rainfall–runoff phenomena in urban environment were better reflected. [ABSTRACT FROM AUTHOR]

Summary In urban stormwater management, “soft” solutions are being widely applied, including stormwater source control. However, no specific resource-effective model is available to assess their effects at the city-scale. As a consequence, source control regulations are often based on simplistic hydrologic assumptions. In this paper, we apply a top-down modeling approach to this problem, and we develop a simple model of flow-rate attenuation in the sewer system, using a numerical empirical approach. Then, we apply the model to source control regulations, assessing which type of regulation is more effective depending on relative positions in a catchment. We show that a model requiring only two types of information about a catchment (concentration time and pluviometry) can provide relevant information on source control effectiveness. This information could be helpful, for example, to define a stormwater zoning. [ABSTRACT FROM AUTHOR]

The seasonal and temporal patterns of N -nitrosodimethylamine (NDMA) formation potentials (FPs) were examined with water samples collected monthly for 21 month period in 12 surface waters. This long term study allowed monitoring the patterns of NDMA FPs under dynamic weather conditions (e.g., rainy and dry periods) covering several seasons. Anthropogenically impacted waters which were determined by high sucralose levels (>100 ng/L) had higher NDMA FPs than limited impacted sources (<100 ng/L). In most sources, NDMA FP showed more variability in spring months, while seasonal mean values remained relatively consistent. The study also showed that watershed characteristics played an important role in the seasonal and temporal patterns. In the two dam-controlled river systems (SW A and G), the NDMA FP levels at the downstream sampling locations were controlled by the NDMA levels in the dams independent of either the increases in discharge rates due to water releases from the dams prior to or during the heavy rain events or intermittent high NDMA FP levels observed at the upstream of dams. The large reservoirs and impoundments on rivers examined in this study appeared serving as an equalization basin for NDMA precursors. On the other hand, in a river without an upstream reservoir (SW E), the NDMA levels were influenced by the ratio of an upstream wastewater treatment plant (WWTP) effluent discharge to the river discharge rate. The impact of WWTP effluent decreased during the high river flow periods due to rain events. Linear regression with independent variables DOC, DON, and sucralose yielded poor correlations with NDMA FP ( R 2 < 0.27). Multiple linear regression analysis using DOC and log [sucralose] yielded a better correlation with NDMA FP ( R 2 = 0.53). [ABSTRACT FROM AUTHOR]

Human faecal contamination poses a widespread hazard for human health. In urban areas, sewer leakage may be an important cause of faecal pollution to surface water. Faecal indicator bacteria (FIB) are the most widely used indicators to monitor surface water quality. However, assessing whether a water body is meeting water quality criteria is made difficult by the high variability of FIB concentrations over time. In this study, the variation of FIB concentration in surface water from tropical urban catchments is investigated. Eleven urban sub-catchments were sampled hourly over 24-hr and samples analysed for FIB. It was found that FIB show a diurnal pattern that is characterised by daytime FIB concentrations that are significantly higher than nighttime FIB concentrations. This observed diurnal variation of FIB closely follows that of sewer flows and contrasts with observations in rural streams where FIB concentrations are known to be low in the daytime and high during the night. Field tracer tests provide qualitative evidence of sewage exfiltration and transport to drains via preferential flow paths. The diurnal FIB variation and field tracer tests indicate the likelihood of surface water contamination due to leaking sewers. The results further suggest that contamination of surface-water drains is likely a widespread problem in tropical urban areas due to extensive drainage networks and the persistence of FIB under tropical conditions. Because of FIB variation over time, the time at which samples are collected is important in being able to capture the daily maximum and minimum FIB concentrations. The Kruskal–Wallis test shows that hourly sampling from 04:00 to 07:00 and from 12:00 to 15:00 results in significantly different FIB concentration (minimum and maximum, respectively). Furthermore, the Wilcoxon-Mann-Whitney test shows that sampling at 12:00 and 14:00 results in significantly higher FIB concentrations, while sampling at 05:00 and 04:00 or 05:00 and 06:00 results in significantly lower FIB concentrations, than sampling at other hours of the day. [ABSTRACT FROM AUTHOR]

Abstract: To make decisions about correcting illicit or inappropriate connections to storm drains, quantification of non-stormwater entries into storm drains was performed using a water flow balance approach, based on data analysis from 2008 to 2011 in a separate storm drainage system in a Shanghai downtown area of 374ha. The study revealed severe sewage connections to storm drains; meanwhile, misconnections between surface water and storm drains were found to drive frequent non-stormwater pumping discharges at the outfall, producing a much larger volume of outfall flows in a short period. This paper presented a methodology to estimate quantities of inappropriate sewage flow, groundwater infiltration and river water backflow into the storm drains. It was concluded that inappropriate sewage discharge and groundwater seepage into storm drains were approximately 17,860m3/d (i.e., up to 51% of the total sewage flow in the catchment) and 3624m3/d, respectively, and surface water backflow was up to an average 28,593m3/d. On the basis of this work, end-of-storm pipe interceptor sewers of 0.25m3/s (i.e., 21,600m3/d) would be effective to tackle the problem of sewage connections and groundwater seepage to storm drains. Under this circumstance, the follow-up non-stormwater outfall pumping events indicate misconnections between surface water and storm drains, featuring pumping discharge equivalent to surface water backflow; hence the misconnections should be repaired. The information provided here is helpful in estimating the magnitude of non-stormwater flow entries into storm drains and designing the necessary pollution control activities, as well as combating city floods in storm events. [Copyright &y& Elsevier]

Highlights: [•] Backcasting storm runoff response using novel method for generating historical LUC. [•] Increased peak flow and reduced response time following peri-urban development. [•] Attribution of flashy response using impervious cover plus storm drainage. [•] Increased impervious cover has greater impact on rural peak flows than urban. [•] Drainage more important determinant of storm response than land use type. [Copyright &y& Elsevier]

• Crowd-sourced data was analyzed to detect explanatory variables for New York City's street flooding. • The adverse contributions of the drainage network towards street flooding occurrence in New York City were revealed. • In some boroughs with a low frequency of reports, street flooding complaints were strongly influenced by small increases in the predictors. Street flooding is problematic in urban areas, where impervious surfaces, such as concrete, brick, and asphalt prevail, impeding the infiltration of water into the ground. During rain events, water ponds and rise to levels that cause considerable economic damage and physical harm. Previous urban flood studies and models have evaluated the factors contributing to street flooding, such as precipitation, slope, elevation, and the drainage network. Yet, due to the complexity of the interconnectedness of these factors and lack of available data, difficulty remains in ascertaining the localized areas prone to and experiencing street flooding. Thus, residents and city management of problem areas are unaware and unable to prepare for street flooding events. This study presents an evaluation of New York City's 311 street flooding reports, via an inference model, as a way to detect the zip codes where street flooding is prevalent. The potential explanatory variables for street flooding complaints were precipitation amounts and 311 sewer back up (water arising from home drains as a result of rainfall), manhole overflow (water arising from manhole covers on the street) and catch basin (a clogged basin preventing rainwater from entering storm drains) complaints. Using Stage IV radar precipitation data and 311 sewer reports, spanning a 10-year period, a Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis, with an embedded Zero-Inflation model is used to detect the variables statistically significant as predictors of flood complaint counts, specific to each zip code. The model is also tested using an Out-of-Sample prediction scheme by training it with the detected explanatory variables. Precipitation was found to be a predictor in 81% of the zip codes. For the infrastructural variables, manhole overflow complaints were significant to street flood complaints in 21% of the zip codes, back up complaints were significant in 41% of the zip codes, and catch basin complaints were significant in 47% of the zip codes. Thus, for an appreciable number of zip codes, infrastructural complaints were found to be predictors of street flooding complaints. This is the first study of its kind to investigate the infrastructural contributions of street flooding by 311 analysis, thereby identifying factors of street flooding, aside from precipitation. Leading contributions of the study include the demonstration of infrastructural impact towards the occurrence of street flooding and also the circumscription to the zip code and borough levels, allowing for tailored preventative actions in critical areas. [ABSTRACT FROM AUTHOR]

• Selection of an ensemble of dynamic velocities and water levels from a database of pre-calculated scenarios using a nearest neighbour approach. • Introduction and analysis of four metrics for precipitation pattern to be used as an indicator for similarity in the nearest neighbour approach. • Guidelines for finding significant locations for error analysis of an ensemble of pre-calculated dynamic velocities and water levels. • Transport path analysis of point source injection in surface water and sewer system flow to analyse the similarity of different velocity fields in an urban catchment. • Indication of the important role of the response time of a sewer system in a metric for similarity of rainfall patterns to predict the resulting velocities. Urban flood warning systems need fast response times between the rainfall forecast and the flood alarm. Flood forecasts from physically based numerical models usually need much computation time. Flood forecasts based on databases from previous events or pre-simulated events can speed up the process of decision making. This work introduces and compares four distance metrics for temporal rainfall patterns used in a nearest neighbour based forecast system for dynamic water levels and velocities during pluvial floods. The system uses a database of 960 pre-calculated flood events. The performance of each metric is evaluated by analysis of time-series of flow variables. For the error quantification,a procedure to find a small number of representative locations in an urban catchment is described. A new approach to quantify the similarity of dynamic flow fields is introduced, which makes use of particle transport tracking. The four distance metrics are tested on forecast for four exemplary pluvial flood events resulting from rainfall of durations between 15 and 50 min and return-periods between 10 and 100 years. The best metric is based on the temporal precipitation pattern and takes the response time of the drainage system into account. If the pattern has a very short duration, a simpler characterisation-metric can be used, which takes the total volume, peak intensity and peak position into account. [ABSTRACT FROM AUTHOR]

• A new comprehensive sustainability index for urban stormwater drainage systems was developed. • The developed sustainability index applied to the western part of Tehran stormwater drainage. Results showed that the study area suffers from significant performance degradation. • Two multi-objective optimization models, with the objectives of maximizing sustainability and minimizing costs, were introduced to rehabilitate the stormwater drainage system. • The effects of considering channels rehabilitation along with BMPs implication were studied. • Results showed that rehabilitating the stormwater networks by BMPs implication and rehabilitating the channels would result in more cost-effective solutions. Urban stormwater drainage systems (USDSs) play an essential role in protecting cities from excessive rainfalls and urban floods. To quantify the performance of the USDSs, a new sustainability index is proposed based on reliability, resiliency, and vulnerability indices. These performance indices evaluate different aspects of a USDS with a comprehensive view of the system's level of service. Using the proposed sustainability index, two USDS design/rehabilitation optimization models are introduced and compared to see which one offers a more sustainable solution and lower implementation cost. The first model (Case I) applies Best Management Practices (BMPs) to an existing USDS to improve sustainability with minimum costs. The second model rehabilitates the channel sizes along with using BMPs. A part of the Tehran Stormwater Drainage System (TSDS) is chosen as the study area to evaluate the proposed methodology. Optimization models are developed by linking the NSGA-II optimization algorithm with the EPA SWMM model. The best solutions are extracted from both cases' Pareto fronts and compared using the Nash bargaining method. Results showed that designing/rehabilitating USDSs by optimizing the BMPs size and channel size would result in a higher sustainability index and lower costs. [ABSTRACT FROM AUTHOR]

Abstract: Perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) are two emerging contaminants that have been detected in all environmental compartments. However, while most of the studies in the literature deal with their presence or removal in wastewater treatment, few of them are devoted to their detection in treated drinking water and fate during drinking water treatment. In this study, analyses of PFOS and PFOA have been carried out in river water samples and in the different stages of a drinking water treatment plant (DWTP) which has recently improved its conventional treatment process by adding ultrafiltration and reverse osmosis in a parallel treatment line. Conventional and advanced treatments have been studied in several pilot plants and in the DWTP, which offers the opportunity to compare both treatments operating simultaneously. From the results obtained, neither preoxidation, sand filtration, nor ozonation, removed both perfluorinated compounds. As advanced treatments, reverse osmosis has proved more effective than reverse electrodialysis to remove PFOA and PFOS in the different configurations of pilot plants assayed. Granular activated carbon with an average elimination efficiency of 64±11% and 45±19% for PFOS and PFOA, respectively and especially reverse osmosis, which was able to remove ≥99% of both compounds, were the sole effective treatment steps. Trace levels of PFOS (3.0–21ng/L) and PFOA (<4.2–5.5ng/L) detected in treated drinking water were significantly lowered in comparison to those measured in precedent years. These concentrations represent overall removal efficiencies of 89±22% for PFOA and 86±7% for PFOS. [Copyright &y& Elsevier]

Abstract: Organic polymers are widely used as flocculants in pretreatment for microfiltration. However, their impact on microfiltration system performance was not well understood. In this study, the effects of three types of polymer flocculants on microfiltration permeate water quality and membrane fouling were evaluated using a hollow fiber membrane under two different operation modes, coagulation/flocculation-sedimentation-microfiltration (CFSM) and coagulation/flocculation-microfiltration (CFM). Interestingly, the effect of polymers on membrane fouling did not appear to reflect their impact on dissolved organic matter content or floc particle properties in the membrane feed water. The addition of polymer flocculants resulted in floc particles of larger size and smaller fractal dimension and slightly enhanced the removal of dissolved organic matter, both of which were expected to reduce membrane fouling. However, it significantly aggravated membrane fouling in all cases except when the positively charged poly(diallyldimethylammonium) chloride was used in the CFSM process. In particular, all polymers greatly increased hydraulically irreversible fouling in the CFM mode. The increased fouling in the CFSM mode is attributed to the residual polymer, while that in the CFM mode is attributed to the enhanced irreversible floc particle attachment on the membrane surface. Considering the potential severe membrane fouling and the small improvement in treated water quality when polymers are used, the application of polymers in microfiltration pretreatment needs to be carefully evaluated. [Copyright &y& Elsevier]

Highlights: [•] Loosely networked, multi-sectoral, actors steer the stormwater transition over decades. [•] Shifting narratives and profiling preliminary scientific evidence builds capacity for regime change. [•] Networked bridging organisations and focus projects protect and deepen the reach of sustainability transitions. [Copyright &y& Elsevier]

Highlights: [•] Invasive and native algae are a part of a reef assemblage located in an urban area. [•] Algal nitrogen (N) composition tested if N was enriched from storm-drain outlets. [•] Elevated N values indicated a mixed, high nutrient environment. [•] Storm-drains as plausible nitrogenous source was not supported. [•] Temporal and spatial values indicate algae incorporated terrestrial derived N. [Copyright &y& Elsevier]