Impacts of a herring gull colony on runoff water quality from an urban green roof.

Green infrastructure (GI) strategies, including green roofs, have become a common, decentralized, nature-based strategy for reducing urban runoff and restoring ecosystem services to the urban environment. In this study, we examined the water quality of incident rainfall and runoff from a green roof installed on top of the Jacob K. Javits Convention Center in New York City. Since the 2014 installation of this green roof, one of the largest in North America, a colony of nesting herring gulls grew to approximately 100 nesting pairs in 2018 and 150 nesting pairs in 2019. Water quality monitoring took place between September 2018 and October 2019. Except for phosphorus on some occasions, we found concentrations of nitrate, nitrite, chlorine, sulfate to be below federal drinking water standards. Levels of the fecal indicator bacteria (FIB), total coliform, E. coli, and Enterococcus, were consistently higher in runoff samples than rainwater, ranging from 150 to over 20,000 CFU/100 mL for E. coli and 100 to over 140,000 CFU/100 mL for total coliform. Quantitative polymerase chain reaction (qPCR) methods were used to search for potential opportunistic pathogens, including Legionella spp., Mycobacterium spp., Campylobacter spp., and Salmonella spp. Discovery of the presence of Catellicoccus marimammalium, a gull-associated marker in runoff water indicates that herring gulls are the likely source of contamination. Due to habitat loss, herring gulls, and other Larus gull species are increasingly nesting on urban roofs, both green (such as at the Javits Center) and conventional (such as on Rikers and Governors Islands). Habitat creation is one of the target ecosystem services desired from GI systems. Although the discharge from the green roof of the Javits Center is directed to the city's sewer system, this study demonstrates the need to treat runoff from green roofs with nesting gull populations if its intended use involves reuse or human contact.

Particle size distribution of total suspended sediments in urban stormwater runoff: Effect of land uses, precipitation conditions, and seasonal variations.

Understanding particle size distribution (PSD) of total suspended sediments in urban runoff is essential for pollutant fate and designing effective stormwater treatment measures. However, the PSDs from different land uses under different weather conditions have yet to be sufficiently studied. This research conducted a six-year water sampling program in 15 study sites to analyze the PSD of total suspended sediments in runoff. The results revealed that the median particle size decreased in the order: paved residential, commercial, gravel lane residential, mixed land use, industrial, and roads. Fine particles less than 125 µm are the dominant particles (over 75%) of total suspended sediments in runoff in Calgary, Alberta, Canada. Roads have the largest percentage of particles finer than 32 µm (49%). Gravel lane residential areas have finer particle sizes than paved residential areas. The results of PSD were compared with previous literature to provide more comprehensive information about PSD from different land uses. The impact of rainfall event types can vary depending on land use types. A long antecedent dry period tends to result in the accumulation of fine particles on urban surfaces. High rainfall intensity and long duration can wash off more coarse particles. The PSD in spring exhibits the finest particles, while fall has the largest percentage of coarse particles. Snowmelt particles are finer for the same land use than that during rainfall events because the rainfall-runoff flows are usually larger than the snowmelt flows.

Longitudinal Analysis of Urban Stormwater Microbiome and Resistome from Watersheds with and without Green Infrastructure using Long-Read Sequencing.

Since stormwater conveys a variety of contaminants into water bodies, green infrastructure (GI) is increasingly being adopted as an on-site treatment solution in addition to controlling peak flows. The purpose of this study was to identify differences in microbial water quality of stormwater in watersheds retrofitted with GI vs. those without GI. Considering stormwater is recently recognized as a contributor to the antibiotic resistance (AR) threat, another goal of this study was to characterize changes in the microbiome and collection of AR genes (resistome) of urban stormwater with season, rainfall characteristics, and fecal contamination. MinION long-read sequencing was used to analyze stormwater microbiome and resistome from watersheds with and without GI in Columbus, Ohio, United States, over 18 months. We characterized fecal contamination in stormwater via culturing Escherichia coli and with molecular microbial source tracking (MST) to identify sources of fecal contamination. Overall, season and storm event (rainfall) characteristics had the strongest relationships with changes in the stormwater microbiome and resistome. We found no significant differences in microbial water quality or the microbiome of stormwater in watersheds with and without GI implemented. However, there were differences between the communities of microorganisms hosting antibiotic resistance genes (ARGs) in stormwater from watersheds with and without GI, indicating the potential sensitivity of AR bacteria to treatment. Stormwater was contaminated with high concentrations of human-associated fecal bacterial genes, and the ARG host bacterial community had considerable similarities to human feces/wastewater. We also identified 15 potential pathogens hosting ARGs in these stormwater resistome, including vancomycin-resistant Enterococcus faecium (VRE) and multidrug-resistant Pseudomonas aeruginosa. In summary, urban stormwater is highly contaminated and has a great potential to spread AR and microbial hazards to nearby environments. This study presents the most comprehensive analysis of stormwater microbiome and resistome to date, which is crucial to understanding the potential microbial risk from this matrix. This information can be used to guide future public health policy, stormwater reuse programs, and urban runoff treatment initiatives.

Understanding the role of biofilms and estimation of life-span of a tire derived aggregates-based underground stormwater treatment system.

The importance of biofilm in tire derived aggregates (TDA) based underground systems has been investigated in this paper, to assess the utilization of tire waste as a cost-effective and sustainable resource for stormwater treatment. The primary objective of this study is to look into the role of biofilms in preventing metal leaching from a TDA based stormwater treatment system and to estimate the life span of a TDA based stormwater treatment system. TDA subjected to different influents to promote or limit the growth of biofilms were analyzed for their leaching and adsorption potential for fifteen different metals through 72 flushes, which is representative of roughly 9 years of TDA exposure to storm events in the upper Midwest USA. Biofilm growth on a manufacturing byproduct (wire exposed-TDA) was higher than on the traditional TDA. The presence of biofilm on TDA had a minor impact on orthophosphate adsorption as observed in a previous study conducted by the authors. However, metals such as iron, zinc and copper, which were previously a concern, had substantially lower leaching into the stored runoff. In addition, the orthophosphate removal from runoff by TDA with a biofilm through 72 flushes indicates that TDA based underground systems can have orthophosphate removal life span beyond 8-9 years. Thus, TDA with biofilms in an underground storage/infiltration chamber has the potential to establish itself as a sustainable, cost-effective, and long life-span alternative for stormwater remediation of orthophosphate pollution without leaching of metals.

Modeling the effect of land use change to design a suitable low impact development (LID) system to control surface water pollutants.

Growth in urbanization has led to increased impervious surfaces, exacerbating flood risks and water quality degradation. This study investigated the impact of land use change and Low-Impact Development (LID) systems on urban runoff quality and quantity in the second region of Tehran. Pioneering an innovative approach, the integration of the Land Change Modeler (LCM) with the Stormwater Management Model (SWMM) signifies a paradigm shift in urban water management. Combined with other hydrological models, this new approach provides a comprehensive method for assessing the future effectiveness of LID practices. The Event Mean Concentration Method (EMC) was used in this study to measure Total Suspended Solids (TSS), Chemical Oxygen Demand (COD), Total Phosphorus (TP), and Zinc (Zn) in urban runoff from five land uses. Results pinpointed transportation land uses as the primary source of pollutants. Using LCM, the study forecasted a surge in urban runoff pollutants by 2030, particularly in the Northwest area of the region due to anticipated land use shifts towards commercial and residential land uses. Model results showed an 11 % increase in TSS over a decade, highlighting the importance of land use change in runoff quality. The study used three types of LIDs to reduce contaminants in dense urban areas. Assessing the impact of LID scenarios on runoff pollutants using SWMM revealed that the bio-retention cell had the best performance, reducing TSS by 20.92 %, and the vegetative swale had the worst performance, reducing TSS by 8.43 %. The study also concluded that combining LIDs would be more effective than using them separately. The results of this study suggest that LID systems can be an effective way to reduce urban runoff pollutants and improve water quality in the second region of Tehran. However, more research is needed to optimize the design and placement of LID systems in different urban areas.

Parameterization of nutrients and sediment build-up/wash-off processes for simulating stormwater quality from specific land uses.

Urbanization changes land cover through the expansion of impermeable surfaces, leading to a significant rise in runoff, sediment, and nutrient loading. The quality of stormwater is related to land use and is highly variable. Currently, stormwater is predominantly described through watershed models that rely minimally, if at all, on field monitoring data. The simple event mean concentration (EMC) wash-off approach by land use is a common method for estimating urban runoff loads. However, a major drawback of the EMC approach is it assumes concentration remains constant across events for a specific land use. Build-up/wash-off equations have been formulated to consider variations in concentration between events. However, several equation parameters are challenging to estimate, making them difficult to use. We conducted a monitoring and modeling study and investigated the impact of land use on stormwater quantity and quality and optimized and investigated the build-up/wash-off parameters for three homogenous urban land uses to estimate nutrients (nitrogen and phosphorus) and sediment loads. Stormwater from commercial, medium-density residential, and transportation land uses was sampled using automatic samplers during storm events, and water quality was characterized for a variety of them for 14 months. Analysis of stormwater samples included assessments for total nitrogen, total phosphorus, and total suspended solids. Results showed that medium-density residential land use had the highest median total nitrogen and total phosphorus event mean concentrations and commercial had the highest median total suspended solids EMCs. Water quality parameters (or build-up/wash-off parameters) exhibited significant variation between land uses, confirming that land use is a key determinant of stormwater quality. The median particle size for each land use was less than 150 µm, indicating that the most common particle size in stormwater was a very fine sand or smaller. This small size should be considered by stakeholders in the design of stormwater treatment systems.

Removal and fate of microplastics in permeable pavements: An experimental layer-by-layer analysis.

The increasing prevalence of microplastics (MP) in urban environments has raised concerns over their negative effects on ecosystems and human health. Stormwater runoff, and road dust and sediment, act as major vectors of these pollutants into natural water bodies. Sustainable urban drainage systems, such as permeable pavements, are considered as potential tools to retain particulate pollutants. This research evaluates at laboratory scale the efficiency of permeable interlocking concrete pavements (PICP) and porous concrete pavements (PCP) for controlling microplastics, including tire wear particles (TWP) which constitute a large fraction of microplastics in urban environments, simulating surface pollution accumulation and Mediterranean rainfall conditions. Microplastic levels in road dust and sediments and stormwater runoff inputs were 4762 ± 974 MP/kg (dry weight) and 23.90 ± 17.40 MP/L. In infiltrated effluents, microplastic levels ranged from 2.20 ± 0.61 to 5.17 ± 1.05 MP/L; while tire wear particle levels ranged between 0.28 ± 0.28 and 3.30 ± 0.89 TWP/L. Distribution of microplastics within the layers of PICP and PCP were also studied and quantified. Microplastics tend to accumulate on the pavements surface and in geotextile layers, allowing microplastic retention efficiencies from 89 % to 99.6 %. Small sized (< 0.1 mm) fragment shaped microplastics are the most common in effluent samples. The results indicate that permeable pavements are a powerful tool to capture microplastics and tire wear particles, especially by surface and geotextile layers. The study aims to shed light on the complex mobilisation mechanisms of microplastics, providing valuable insights for addressing the growing environmental concern of microplastic pollution in urban areas.

Assessing the defecation practices of unsheltered individuals and their contributions to microbial water quality in an arid, urban watershed.

Outdoor defecation by people experiencing homelessness is frequently perceived as a potentially large source of human fecal pollution and a significant source of health risk in urban waterbodies with recreational contact. The goal of this study was to count the number of people experiencing homelessness and quantifies their sanitation habits in an urban river corridor setting, then use this information for estimating human fecal pollutant loading on a watershed scale. Two types of census counts were conducted including periodic point-in-time counts over six years and weekly counts of encampments. While the population census varied from count-to-count, the range of population estimates in the river corridor varied from 109 to 349 individuals during the six-year span, which mirrored the weekly counts of encampments. A face-to-face survey of people experiencing homelessness assessed the sanitation habits of the unsheltered population (N = 63), including outdoor defecation frequency and containment practices. Overall, 95 % of survey respondents reported defecating outdoors; 36 % practiced outdoor defecation between 4 and 7 days/week and 27 % practiced outdoor defecation <1 day/week. Of those that did practice outdoor defecation, 75 % contained their feces in a bucket or bag, thereby limiting fecal material contributions to the river; 6.7 % reported defecating on low ground near the river that could wash off when flood waters rise during a storm event. Only a single survey respondent reported defecating directly into the river. Based on literature values for average HF183 output for an adult human, and the average rainfall in the urban watershed, the total watershed contribution of HF183 averaged 1.2 × 1010 gene copies per storm event (95 % CI: 0.9 × 1010-1.6 × 1010) along the 41 km stretch of river in this study. This human fecal loading estimate is at least two orders of magnitude less than cumulative HF183 loading from all human sources measured at the bottom of the watershed.

Effect of landscape irrigation regulations on runoff volume from low-density residential catchments during two California droughts.

The severe drought in California (2012-2016) generated significant public and government concern. State and local watering regulations were enacted to reduce residential and commercial water-use during the droughts. This study presents a comparison of residential runoff volumes before and after local landscape irrigation regulations were enacted during the droughts of 2008 and 2012-2016. Each sampling site (Folsom 1 and Folsom 2) was a storm drain outfall that drained a low-density residential catchment in the City of Folsom. Dry season runoff measured at the sampling sites represents neighborhood outdoor water waste, mainly from landscape irrigation. During the drought of 2012-2016, median runoff flows were significantly reduced after local landscape irrigation regulations were enacted. The daily runoff pattern was also highly influenced by regulation, with reductions of daily peak runoff flows on 4-5 days in a week after watering regulations were enacted. The number of peak flow events in the daily runoff pattern were reduced during this period. In addition, a significant reduction in mean runoff volume occurred. Based on these results, the watering regulations enacted by the City of Folsom had a positive effect on reducing urban runoff from residential neighborhoods during the dry season. As the results are from monitoring sites in a relatively small geographical area, further work should evaluate reductions in irrigation runoff from other California locations to determine if this is a localized phenomenon.

Urban stormwater quality: A review of methods for continuous field monitoring.

Urban stormwater is contaminated by a wide range of substances whose concentrations vary greatly between locations, as well as between and during rain events. This literature review evaluates advantages and limitations of current methods for using continuous water quality monitoring for stormwater characterization and control. High-temporal-resolution measurements have been used to improve the understanding of stormwater quality dynamics and pollutant pathways, facilitate the performance evaluation of stormwater control measures and improve operation of the urban drainage system with real-time control. However, most sensors used to study stormwater were developed for either centralized water treatment or natural water contexts and adaptation is necessary. At present, the primary application of interest in stormwater - characterization of pollutant concentrations - can only be achieved through the use of indirect measurements with site-specific relationships of pollutants to basic physical-chemical parameters. In addition, various problems arise in the field context, associated with intermittent or variable flow rates, the accumulation of debris and sediment, adverse conditions for electrical equipment and human factors. Obtaining reliable continuous stormwater quality data requires the adoption of best practices, including the calibration and regular maintenance of sensors, verification of data and accounting for the considerable uncertainties in data; however, the literature review showed that improvement is needed among the scientific community in implementing and documenting these practices.

Inter-event and intra-event dynamics of microplastic emissions in an urban river during rainfall episodes.

Urban rivers represent the major conduits for land-sourced microplastics in the global oceans, yet the real-time dynamics of their emissions in rivers during rainfall (and runoff) events are poorly understood. Herein, we report the results of high-frequency sampling of microplastic particles (MPs) and fibers (MPFs) in the surface water of an urban river in Japan over the course of three rainfall events (i.e., light, moderate, and heavy rainfalls). The event mean concentrations (EMCs) of MPs amounted to 35,000 items/m3, 929,000 items/m3, and 331,000 items/m3; and the corresponding total loads were 0.5 kg, 19.8 kg, and 35.0 kg for light, moderate and heavy rainfalls, respectively. The inter-event total loads of MPs correlate well with the total rainfall, while the concentrations were linked with the number of antecedent dry days. The dynamic trends show that <2000 µm MPs displayed first flush effects during light to moderate rainfall events (>50% mass discharged with the initial 20-40% of flow). Small-sized MPs (10-40 µm) mobilized rapidly at lower rainfall intensities, whereas MPs over 2000 µm discharged immediately after the peak rainfall intensity. Moreover, <70 µm MPs depicted a surge following heavy rainfall events due to turbulent flow conditions reverting the deposited MPs into suspension. Overall, the three events increased the loads by 4-110 folds, and EMCs by 10-350 folds compared to the concentrations during dry weather while portraying a significant impact on 300-1000 µm MPs. The dynamics of MPs were correlated with those of suspended solids in river water, and the characteristics were comparable to the same of road dust sampled in Japan. Although the dynamic trends between MPs and MPFs in river water were comparable, MPFs were relatively less impacted by rain, likely due to the intervention of separate sewer systems in the study area.

Distribution of pyrethroid insecticides in urban storm drain structures: Catch basins, open channels, and outfalls.

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.

Water quality improvement project for initial rainwater pollution and its performance evaluation.

Efficiently addressing initial rainwater pollution is crucial for mitigating urban water pollution. However, the performance evaluation of initial rainwater pollution control project is rarely introduced. In this study, the architecture of effective comprehensive engineering measures for improving the water quality of initial rainwater in Anhui Province, China, was described. Three water quality indicators, ammonia nitrogen (NH3-N), chemical oxygen demand (COD), and total phosphorus (TP), were selected to explore the severity of urban pollution caused by initial rainwater under various rainfall scenarios. A single-factor evaluation method was used to contrast and assess the benefits of the initial rainfall interception project in terms of water quality enhancement. Results showed that initial rainfall pollution was gentler under light rainfall conditions but more prominent under moderate and heavy conditions. The percentages of NH3-N, COD, and TP in Lotus Pond that met the tertiary drinking water standard were 100%, 74.91%, and 100% with great improvement, and the average concentrations of NH3-N, COD, and TP in Fushan Road Drainage have decreased by 91.43%, 10.49%, and 57.33% respectively, after the construction of the interception project. These indicated that the nitrogen and phosphorus pollution were successfully controlled by the control techniques in both locations, but COD concentration has to be addressed with more specialized strategies. Overall, the water quality improvement project for initial rainwater pollution plays a great role in effectively governing initial rainwater pollution and improving river water quality, and provides an effective technical reference for urban water ecological environment management.

Do drinking water treatment residuals underperform in the presence of compost in stormwater media filters?

Drinking water treatment residuals (WTR), a waste-derived product, are often recommended to use as an amendment in stormwater biofilters to enhance their capacity to remove phosphate and microbial pollutants. However, their efficacy has been assumed to remain high in the presence of compost, one of the most common amendments used in biofilters. This study tests the validity of that assumption by comparing the removal capacities of WTR-amended biofilters with and without the presence of compost. Our results show that amending sand with WTR increased E. coli removal by at least 1-log, but the addition of compost in the sand-WTR media lowered the removal capacity by 13 %. Similarly, the addition of WTR to sand improved phosphate removal to nearly 1177 %, but the removal decreased slightly by 8 % when adding compost to the media. The results confirmed that dissolved organic carbon (DOC) leached from the compost could compete for adsorption sites for bacteria and phosphate, thereby lowering WTR's adsorption capacity based on the amount of DOC adsorbed on WTR. Collectively, these results indicate that the stormwater treatment industry should avoid mixing compost with WTR to get the maximum benefits of WTR for bacterial removal and improve the performance lifetime of WTR-amended biofilters.

Measuring sediment loads and particle size distribution in road runoff: Implications for sediment removal by stormwater control measures.

Road runoff contributes an array of pollutants which degrade the quality of receiving waters. Sediment conveyed in runoff results in loss of habitat and loss of reservoir capacity, among other undesirable impacts. To select and design stormwater control measures (SCMs), the sediment particle size distribution (PSD) is needed to quantify the required hydraulic retention time for particle settling and to understand what other treatment processes (e.g., filtration) are needed to meet sediment removal targets. A two-year field monitoring study was undertaken across the state of Ohio, USA, to evaluate the PSD of sediment in runoff at twelve roads. The highest TSS concentrations were observed on interstate highways (highest annual average daily traffic [AADT]) and minor arterials (low AADT), suggesting factors beyond AADT, such as antecedent dry period, rainfall intensity, and windborne dust and particulates, contribute to the varied sediment characteristics in runoff. The median TSS load across all samples collected was 2.7 kg/ha per storm event, while annual TSS loads for the monitoring sites varied from 98 kg/(ha·yr) to 519 kg/(ha·yr), with a mean value of 271 kg/(ha·yr). Particle size distributions varied across the monitoring sites, with mean and median d50 of 48.6 µm and 52.5 µm, respectively. Interstate highways (highest AADT) had significantly finer PSDs than other functional classes, while roads in low density residential areas had coarser PSDs than other land uses. Observed differences in PSD across road characteristics may guide SCM selection; dry detention basins and wet ponds/wetlands were predicted to provide effective removal across a variety of PSDs, while TSS reductions provided by hydrodynamic separators and high-flow media filters (which effectively remove larger particles) may be maximized in areas with coarser PSDs (e.g., roads surrounded by low density residential areas studied herein).

Apical and mechanistic effects of 6PPD-quinone on different life-stages of the fathead minnow (Pimephales promelas).

N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine-quinone (6PPD-quinone) is an emerging contaminant of concern that is generated through the environmental oxidation of the rubber tire anti-degradant 6PPD. Since the initial report of 6PPD-quinone being the cause of urban runoff mortality syndrome of Coho salmon, numerous species have been identified as either sensitive or insensitive to acute lethality caused by 6PPD-quinone. In sensitive species, acute lethality might be caused by uncoupling of mitochondrial respiration in gills. However, little is known about effects of 6PPD-quinone on insensitive species. Here we demonstrate that embryos of fathead minnows (Pimephales promelas) are insensitive to exposure to concentrations as great as 39.97 µg/L for 168 h, and adult fathead minnows are insensitive to exposure to concentrations as great as 9.4 µg/L for 96 h. A multi-omics approach using a targeted transcriptomics array, (EcoToxChips), and proton nuclear magnetic resonance (1H NMR) was used to assess responses of the transcriptomes and metabolomes of gills and livers from adult fathead minnows exposed to 6PPD-quinone for 96 h to begin to identify sublethal effects of 6PPD-quinone. There was little agreement between results of the EcoToxChip and metabolomics analyses, likely because genes present on the EcoToxChip were not representative of pathways suggested to be perturbed by metabolomic analysis. Changes in abundances of transcripts and metabolites in livers and gills suggest that disruption of one­carbon metabolism and induction of oxidative stress might be occurring in gills and livers, but that tissues differ in their sensitivity or responsiveness to 6PPD-quinone. Overall, several pathways impacted by 6PPD-quinone were identified as candidates for future studies of potential sublethal effects of this chemical.

Occurrence and dynamics of microplastics and emerging concern microparticles in coastal sediments: Impact of stormwater upgrade and port-associated facilities.

Urban runoff is a significant source of microplastic pollution in aquatic environments, especially in coastal areas. Despite urban stormwater runoff being considered a major pathway of anthropogenic particles there's no studies about the impact of stormwater upgrades on microparticle transport. Moreover, due to the influence of anthropogenic activities, including maritime traffic and maintenance, on coastal environments, it is crucial to identify plastic debris from both inland and in-shore sources. This study evaluates characteristics, abundance, and distribution of microplastics in subtidal sediments from the southwestern Atlantic region, influenced by a recently upgraded stormwater outfall and port facilities. Herein, we have analyzed temporal trends, including seasonal dynamics and their relation with the pre- and post-upgrade of the stormwater outfall. Three main types of anthropogenic microparticles were observed: common plastic (MPs), paints (Pps), and tire wear particles (TWPs). Microparticle groups varied in morphology, color, and size distribution, including uncommon microparticle debris. Analysis by FTIR and Raman spectroscopies allows the identification of polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, polystyrene, polyamide, and polyacrylonitrile polymers for MPs mainly. Pigments such as Naphthol AS, phthalocyanine, and quinacridone have been identified in Pps. SEM-EDS and FTIR analysis of collected TWPs revealed similar trace metals constituents and infrared signals to those observed in tire road samples. Spatial and temporal abundances of microparticle groups were significantly different (p < 0.05), mainly related to the distance from the stormwater outfall and seasons. TWPs showed the most significant seasonal increment rate among pre and post-upgrade periods. Furthermore, the upgrades made to the stormwater system have been observed to intensify the transport and increase the presence of specific anthropogenic microparticles in subtidal sediments. Based on these findings, the occurrence of TWPs emerges as a reliable urban runoff indicator to differentiate ex and in-situ sources in multipolluted coastal environments.

A study of 101 organic substances in gully pot sediments accumulated over a one-year period in Stockholm, Sweden.

Stormwater runoff is a key pathway for diffuse pollutants to enter receiving waters. Mitigating measures include pollutant substitution, restricting their release into the urban technosphere and limiting the (re-)mobilisation of substances to minimise their negative impacts on receiving waters. Gully pots (GPs) are one of the most ubiquitous urban drainage infrastructure components, providing both a drainage function and limiting the onward transport of pollutants through in-pot sedimentation processes. In this study, sediments accumulated over a one-year period were collected from 26 GPs in catchments of four land-use types in Stockholm, Sweden. Sediments were analysed for 101 organic substances from eight substance groups (hydrocarbons, polycyclic aromatic hydrocarbons, alkylphenols, polychlorinated biphenyls, phthalates, organotins, per- and polyfluoroalkyl substances and brominated fire retardants) to inform an assessment of their occurrence and net accumulation rates over a typical unit operation period. A total of 63 substances were quantified in at least one GP, with aliphatic hydrocarbons, phthalates and organotins quantified in all GP sediments, highlighting their ubiquitous use. The identification of 14 and 21 organic substances in two pedestrian/bike path GPs emphasise the contribution of non-vehicular sources to diffuse pollutant loads. Significantly higher mass accumulation rates of 4-tert-octylphenol, 4-nonylphenols, formaldehyde, dioctyltin and dibutyltin are identified in commercial catchment GPs suggesting the need to enhance source-tracing and runoff quality-control measures within catchments of this land-use type. Sediments in 25 GPs were identified with at least one substance exceeding toxicology-based threshold values, highlighting the runoff quality-control function of GPs in reducing the potential ecotoxic impacts on recipients.

Urban runoff mortality syndrome in zooplankton caused by tire wear particles.

Stormwater runoff from roadways is a global threat to water quality, aquatic organisms, and ecosystems. Tire tread wear particles (TWP) from roadway runoff may lead to urban runoff mortality syndrome (URMS) in some aquatic organisms. We tested the hypothesis that urban runoff from roadways can kill zooplankton. Both roadway runoff and TWP leachate were acutely lethal to a model species, the water flea Daphnia pulex. Life table experiments further revealed the lowered survival rates, intrinsic rate of increase, average life span, and net productive rate of D. pulex when exposed to roadway runoff and TWP leachate. The tire rubber antioxidant N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylenediamine (6PPD) mainly contributed to the TWP toxicity. The toxicity of TWP and 6PPD extracted varied with time in nature. Cladocerans and rotifers were more sensitive to TWP and 6PPD than copepods. These results demonstrate the presence of URMS in zooplankton, which may cascade through food webs and affect aquatic ecosystems.

Effects of rainfall characteristics on runoff quality parameters within an industrial sector in Tennessee, USA.

The relationship between rainfall characteristics and pollutant discharge has rarely been investigated in industrial sectors. To address this need, we investigated the pollutant concentrations of surface runoff and the correlation between pollutant discharge and rainfall characteristics using the self-reported stormwater quality data collected under the Tennessee Multi-Sector Permit program for two industrial facilities in West Tennessee. The variation of certain stormwater quality parameters over this period was utilized as an indicator to evaluate the effectiveness of control measures implemented at these two facilities. Furthermore, the Water Quality Index (WQI) as an indicator to assess the temporal changes in stormwater quality at industrial facilities was determined using the Weighted Sum (WSM) and Canadian Council of Ministers of the Environment (CCME) methods. The principal component analysis (PCA) and Pearson correlation coefficient were utilized to understand the correlation between runoff quality parameters, rainfall characteristics, and the sources of pollutants. The results demonstrated lower WQI indices using the WSM method compared to the CCME method. The data analysis revealed that 93.1%, 100%, 86.2%, and 48.3% of Al, Mg, Cu, and Fe experienced a concentration greater than the benchmark level, respectively. There was a significant relationship between Total suspended solids (TSS) and Al, Chemical Oxygen Demand (COD), Fe, oil and grease (O&G), and Zn concentrations. As a result, TSS could be a priority pollutant for designing various best management practices (BMPs) and low impact developments (LIDs). The result of the PCA and Pearson correlation coefficient showed that Al concentration made a significant correlation with the rainfall depth and rainfall duration. This analysis also illustrated that biochemical oxygen demand (BOD5), COD, and O&G concentrations were highly correlated with antecedent dry days (ADDs). However, pH was more related to rainfall depth and rainfall intensity. This study informs both regulatory agencies and industry stakeholders regarding the importance of evaluating self-reported stormwater quality data.