Valuing stakeholder preferences for environmental benefits of stormwater ponds: Evidence from choice experiment.

With population growth driving urban expansion in many cities in the United States, there is a need for a sustainable way to manage stormwater. Green stormwater infrastructure (GSI) is considered an innovative way to handle stormwater because of its potential to provide multiple ecosystem services (ES) beyond flooding reduction. However, there is limited research regarding the society's perceived value for GSI practices' co-benefits. This study utilized stated-preference data obtained from a choice experiment in an online survey of 1159 South Carolina (SC) residents to estimate a monetary value for the ES provided by wet detention ponds- the most widely adopted stormwater practice in coastal counties of SC. The benefits examined are flooding reduction, water quality, wildlife habitat, recreation, and scenic beauty. The data were analyzed using a Mixed logit formulation. Considering the differences across the state, the model was estimated separately for five counties. Findings indicate that residents are willing to pay $13.8 to $37.8 annually for a 50% improvement in pollutant removal efficiency of ponds in addition to their current stormwater fee. Also, they are willing to pay $12.5 to $42.9 per year for the nearest pond to have buffer vegetation and wildlife. They are also likely to pay $5 to $22.5 for ponds to contribute to their neighborhood's scenic beauty. Furthermore, the results indicate that respondents from three counties are willing to pay $5.4 to $13.2 for a 50% improvement in flooding reduction, while those from two counties are likely to pay $3.9 to $4.9 for ponds to have recreational benefits. The findings of the study could help stormwater managers in designing their stormwater management programs, especially for better evaluation of stormwater utility fees.

Developing an ecosystem model of a floating wetland for water quality improvement on a stormwater pond.

An ecosystem model was developed to assist with designing and implementing a floating wetland (FW) for water quality management of urban stormwater ponds, focusing on nitrogen (N) removal. The model is comprised of three linked submodels: hydrology, plant growth, and nitrogen. The model was calibrated with the data that resulted from a FW constructed and implemented as part of an interdisciplinary pedagogical project on a university campus, titled "The Rain Project", which raised awareness of stormwater issues while investigating the potential application of green infrastructure for sustainable stormwater management. The FW had been deployed during the summer of 2015 (i.e., May through mid-September) on a major stormwater pond located at the center of the Fairfax Campus of George Mason University near Washington, D.C. We used the model to explore the impact of three design elements of FW (i.e., hydraulic residence time (HRT), surface area coverage, and primary productivity) on the function of FW. Model simulations showed enhanced N removal performance as HRT and surface area coverage increased. The relatively low macrophyte productivity observed indicates that, in the case of our pond and FW, N removal was very limited. The model results suggest that even full pond surface coverage would result in meager N removal (∼6%) at a HRT of one week. A FW with higher plant productivity, more representative of that reported in the literature, would require only 10% coverage to achieve similar N removal efficiency (∼7%). Therefore, macrophyte productivity appears to have a greater impact on FW performance on N removal than surface area coverage or pond HRT. The outcome of the study shows that this model, though limited in scope, may be useful in aiding the design of FW to augment the performance of degraded stormwater ponds in an effort to meet local water quality goals.

Buoyant microplastics in freshwater sediments - How do they get there?

The accumulation of microplastics (MPs) in the sediments of a stormwater treatment pond was studied to gain knowledge on how these facilities protect the natural environment against this emerging pollutant. Thirteen sediment samples were analyzed for MPs down to 10 µm, mapping the pattern of accumulation in the pond. The average abundance in terms of MP-number and mass was 11.8 µg kg-1 and 44,383 item kg-1, respectively. They were rather unevenly distributed, with concentrations varying up to two orders of magnitude within the pond, showing that a trustworthy quantification of MPs retained by such units must rely on many and well-distributed subsamples. Buoyant MPs made up 95.4 % of the MP-mass and 83.5 % of the MP-number and in most of the sampled locations, polypropylene dominated the polymer fingerprint, followed by polyethylene. No spatial pattern in the distribution of MPs in the pond was identified. Instead, the MP content correlated to the organic matter and silt content, indicating that the processes leading to deposition could be similar. A computational fluid dynamics model was set up and used to simulate the transport mechanisms governing the conveyance of MPs in the pond from water to sediments. The results showed that the combination of advection and dispersion were likely the driving mechanism for buoyant (and non-buoyant) MPs to get in contact with the sediment bed and spread over the pond. Once in contact with the sediments, the MPs would have some probability of being permanently incorporated and hereby preventing them from entering the downstream aquatic environment.

Fate of antimony contamination generated by road traffic - A focus on Sb geochemistry and speciation in stormwater ponds.

Although antimony (Sb) contamination has been documented in urban areas, knowledge gaps remain concerning the contributions of the different sources to the Sb urban biogeochemical cycle, including non-exhaust road traffic emissions, urban materials leaching/erosion and waste incineration. Additionally, details are lacking about Sb chemical forms involved in urban soils, sediments and water bodies. Here, with the aim to document the fate of metallic contaminants emitted through non-exhaust traffic emissions in urban aquatic systems, we studied trace element contamination, with a particular focus on Sb geochemistry, in three highway stormwater pond systems, standing as models of surface environments receiving road-water runoff. In all systems, differentiated on the basis of lead isotopic signatures, Sb shows the higher enrichment factor with respect to the geochemical background, up to 130, compared to other traffic-related inorganic contaminants (Co, Cr, Ni, Cu, Zn, Cd, Pb). Measurements of Sb isotopic composition (δ123Sb) performed on solid samples, including air-exposed dusts and underwater sediments, show an average signature of 0.07 ±â€¯0.05‰ (n = 25, all sites), close to the δ123Sb value measured previously in certified reference material of road dust (BCR 723, δ123Sb = 0.03 ±â€¯0.05‰). Moreover, a fractionation of Sb isotopes is observed between solid and dissolved phases in one sample, which might result from Sb (bio)reduction and/or adsorption processes. SEM-EDXS investigations show the presence of discrete submicrometric particles concentrating Sb in all the systems, interpreted as friction residues of Sb-containing brake pads. Sb solid speciation determined by linear combination fitting of X-Ray Absorption Near Edge Structure (XANES) spectra at the Sb K-edge shows an important spatial variability in the ponds, with Sb chemical forms likely driven by local redox conditions: "dry" samples exposed to air exhibited contributions from Sb(V)-O (52% to 100%) and Sb(III)-O (<10% to 48%) species whereas only underwater samples, representative of suboxic/anoxic conditions, showed an additional contribution from Sb(III)-S (41% to 80%) species. Altogether, these results confirm the traffic emission as a specific source of Sb emission in surface environments. The spatial variations of Sb speciation observed along the road-to-pond continuum likely reflect a high geochemical reactivity, which could have important implications on Sb transfer properties in (sub)surface hydrosystems.

Molecular characterization of dissolved organic matter in urban stormwater pond and municipal wastewater discharges transformed by the Florida red tide dinoflagellate Karenia brevis.

Karenia brevis blooms occur almost annually in southwest Florida, imposing significant ecological and human health impacts. Currently, 13 nutrient sources have been identified supporting blooms, including nearshore anthropogenic inputs such as stormwater and wastewater outflows. A 21-day bioassay was performed, where K. brevis cultures were inoculated with water sourced from three stormwater ponds along an age gradient (14, 18, and 34 yrs.) and one municipal wastewater effluent sample, with the aim of identifying biomolecular classes and transformations of dissolved organic matter (DOM) compounds used by K. brevis. All sample types supported K. brevis growth and showed compositional changes in their respective DOM pools. Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) catalogued the molecular composition of DOM and identified specific compound classes that were biodegraded. Results showed that K. brevis utilized species across a wide range of compositions that correspond to amino sugars, humic, and lignin-like biomolecular classes. The municipal wastewater and the youngest stormwater pond (SWP 14) effluent contained the largest pools of labile DOM compounds which were bioavailable to K. brevis, which indicates younger stormwater pond effluents may be as ecologically important as wastewater effluents to blooms. Conversely, generation of DOM compounds of greater complexity and a wide range of aromaticity was observed with the older (SWP 18 and SWP 34) stormwater pond treatments. These data confirm the potential for stormwater ponds and/or wastewater to contribute nutrients which can potentially support K. brevis blooms, revealing the need for improved nutrient retention strategies to protect coastal waters from the potential ill effects of urban effluent.

Highway stormwater ponds as islands of Odonata diversity in an agricultural landscape.

Stormwater management ponds, which are constructed to retain excess runoff and pollutants from traffic, play an important role in the freshwater biodiversity in highly modified areas. However, their roles in agricultural and semi-natural landscapes remain largely unexplored. In this study, we used Odonata as a bioindicator to compare a set of highway stormwater ponds and surrounding ponds within an agricultural and semi-natural landscape to examine the extent to which stormwater ponds act as biodiversity refuges. We analyzed the differences in environmental parameters and the richness, compositions, and conservation values of the odonate communities of stormwater and surrounding ponds. We also examined the factors controlling the differences in the communities of both pond types. The stormwater ponds were smaller, less eutrophicated, less shaded by trees, less stocked with fish, and less connected with other waterbodies than the surrounding ponds. However, they had a higher plant diversity and pH values and were more densely overgrown with vegetation. Compared with surrounding ponds, stormwater ponds had a higher Odonata richness and ß-diversity, but their taxonomic distinctness was significantly lower. Therefore, stormwater ponds hosted more variable communities but their assemblages were taxonomically similar. Indicator species were only identified in stormwater ponds. Furthermore, stormwater ponds harbored more species with higher conservation values. The most important factors affecting the differences between stormwater and surrounding ponds were the trophic state, relative tree shading, and fish stocking intensity. With their increase, the richness and rarity decreased. Our results highlight the potential of stormwater ponds to enhance the biodiversity outside urban areas by providing specific habitat conditions that are unique to the surrounding agricultural landscape. In addition, we suggest management practices that can be used to enhance their biodiversity conservation function.

The interaction between spatial variation in habitat heterogeneity and dispersal on biodiversity in a zooplankton metacommunity.

It is hypothesized that biodiversity is maintained by interactions at local and regional spatial scales. Many sustainability plans and management practices reflect the need to conserve biodiversity, yet once these plans are implemented, the ecological consequences are not well understood. By learning how management practices affect local environmental factors and dispersal in a region, ecologists and natural resource managers can better understand the implications of management choices. We investigated the interaction of local and regional scale processes in the built environment, where human-impacts are known to influence both. Our goal was to determine how the interaction between spatial variation in habitat heterogeneity in algal management of urban ponds and dispersal shape biodiversity at local and regional spatial scales. A twelve-week mesocosm study was conducted where pond management and dispersal were manipulated to determine how spatial variation in habitat and dispersal from various source pools influence zooplankton metacommunities in urban stormwater ponds. We hypothesized that dispersal from managed or unmanaged source pools will lead to community divergence and local management practices will act as an environmental filter, both reducing beta diversity between managed ponds and driving compositional divergence. Our results suggest that zooplankton dispersal from managed or unmanaged source pools was important to explaining divergence in community composition. Furthermore, local management of algae marginally reduced compositional turnover of zooplankton among ponds but did not lead to significant divergence in community composition. Management practices may act as strong environmental filters by reducing beta diversity between ponds. As hypothesized, source pool constraints led to compositional divergence and local management practices resulted in reduced compositional turnover between ponds. The results of this study suggest that sustainability and management plans may have complex effects on biodiversity both within and across spatial scales.

Copper concentration data for water, sediments, and vegetation of urban stormwater ponds treated with copper sulfate algaecide.

We characterized copper (Cu) concentrations in the water, sediments, and shoreline plants of stormwater ponds in the urban Tampa, Florida area. We selected 6 urban residential stormwater ponds that receive summer wet season (May to September) Cu sulfate applications at least twice a month. We collected triplicate water and sediment samples from each pond and analyzed for Cu, as well as nutrient pools (inorganic N and P) and a suite of other physicochemical properties (e.g., water temperature, pH, conductivity, alkalinity, etc.). We analyzed shoreline plant tissue samples for Cu. The raw dataset provides values for Cu concentrations in water, sediments and plant tissue, and other measured parameters in water and sediments. This dataset is important for characterizing the fate and potential mobility of Cu in freshwater ponds treated with Cu sulfate algaecides. This applied research data will provide baseline understanding of Cu concentrations in water, sediments, and select plant tissue samples, providing insights on potential toxicity of Cu and any threats that Cu sulfate algaecides may pose to aquatic organisms and downstream waters. This dataset can also inform future research designs aimed at elucidating the effects of Cu on denitrifying bacteria and N removal in stormwater pond ecosystems. Finally, the plant tissue data shows variable Cu concentrations among plant species, and this data can inform future phytoremediation experiments.

Water quality effects on dragonfly and damselfly nymph communities: A comparison of urban and natural ponds.

Cities are increasingly using constructed ponds to mitigate flooding and downstream water pollution from urban runoff. As a result, these stormwater ponds can have poor water quality, yet they can also attract wildlife. In this study, the effects of water quality on dragonflies and damselflies (Odonata) were determined in stormwater ponds (n = 41) and natural reference ponds (n = 10) of similar size across the National Capital Region of Canada. A total of 38 chemical/physical water quality variables along with Odonata nymph abundance and taxonomic composition were sampled at each pond. Chloride concentrations exceeded the guideline for the protection of aquatic life at over two-thirds of the stormwater ponds. Among all the metals tested, only Cu exceeded guidelines at many stormwater ponds. Both dragonfly and damselfly nymphs were on average less abundant in the stormwater ponds in comparison to the natural ponds. Ponds with high concentrations of chloride and metals typically had lower dragonfly abundance. Dragonfly community structure was significantly influenced by high chloride (or conductivity), which likely originates from winter road salting. In contrast, damselfly community structure in the stormwater ponds was similar to that found in natural ponds, with nutrients and metals explaining a small percent of variation in community structure. A water quality index developed to assess habitats for the protection of aquatic life did not significantly explain Odonata abundance or measures of diversity and may not be suitable in assessing pond habitat quality. To improve pond habitats within cities, efforts should be directed at reducing the amount of impervious surface and road salt usage within catchment basins.

A comparative study of macroinvertebrate biodiversity in highway stormwater ponds and natural ponds.

The use of stormwater ponds along the highways is shown to be an effective alternative to conventional systems, which are usually sewers. These ponds have the potential to combine their primary function of pollution and peak flow control with the promotion of biodiversity. The present study focuses on comparing natural and highway stormwater ponds in terms of environmental conditions and biodiversity of macroinvertebrate communities. Twelve highway stormwater ponds and nineteen natural ponds (located within or in the vicinity of cultivated landscape) were explored for the number of taxa, community composition, and selected environmental variables: pH, conductivity, pond surface area, the number of ponds within 1 km radius, and the distance to nearest neighboring pond. Highway stormwater ponds showed much higher conductivity, which is a good proxy for chloride concentration and highway pollutants. In addition, the surface area of stormwater ponds was almost twice as big as that of natural ponds. The biological community composition was very different between the two types of ponds, and the number of taxa was slightly higher in the highway stormwater ponds. The most important variables responsible for the variation in the biological community composition were conductivity, pond surface area, and the number of ponds within 1 km radius. This study supports that, in addition to their role in pollution and peak flow control, stormwater ponds have the potential to provide a habitat that may otherwise be unavailable along the highway.

Hypoxic conditions in stormwater retention ponds: potential for hydrogen sulfide emission.

Improper design and maintenance of stormwater ponds (SWPs) may lead to hypoxic conditions, poor water quality and the production of hydrogen sulfide (H2S). The objective of this study is to develop a comprehensive understanding of hypoxic conditions of SWPs, with a focus on the potential for H2S production and emission. This study was conducted at two retention SWPs in Ottawa, Canada; a problematic pond with the propensity for H2S emission and a reference pond that did not demonstrate H2S emission. The investigation illustrated a significant impact of low dissolved oxygen (DO) concentrations, hypoxic conditions, on the concentration of total sulfides in the water column. Both ponds were shown to periodically experience hypoxic conditions at depth, especially during summer periods with less precipitation and across longer periods of winter, ice-covered conditions. The problem pond, however, was shown to experience lower DO and longer hypoxic conditions than the reference pond in both non-ice-covered and ice-covered conditions due to greater depth and a longer hydraulic retention time. Hypoxic conditions were initiated at the deepest locations in the problem pond and subsequently were spread across the entirety of the pond under winter, ice-covered conditions. Algal biomass (Chlorophyll-a) and soluble biochemical oxygen demand concentrations were shown to not likely be significant factors in the development of hypoxia in the H2S-generating pond. Algal blooms of colonial Chrysophyceae, Synura, a known mixotroph, were observed during ice-covered conditions in the problem pond possibly due to stress-coping mechanisms of algae.

DNA metabarcoding adds valuable information for management of biodiversity in roadside stormwater ponds.

ABSTRACT: Stormwater ponds are used to compensate for the adverse effects that road runoff might have on the natural environment. Depending on their design and placement, stormwater ponds can act as both refugia and traps for local biodiversity. To evaluate the impact of stormwater ponds on biodiversity, it is critical to use effective and precise methods for identification of life associated with the water body. DNA metabarcoding has recently become a promising tool for identification and assessment of freshwater biodiversity.Using both morphology and DNA metabarcoding, we analyze species richness and biological composition of samples from 12 stormwater ponds and investigate the impact of pond size and pollution levels in the sediments and water column on the macroinvertebrate community structure.DNA metabarcoding captured and identified more than twice the number of taxa compared to morphological identification. The (dis)similarity of macroinvertebrate community composition in different ponds showed that the ponds appear better separated in the results obtained by DNA metabarcoding, but that the explained variation is higher for the results obtained by morphologically identification, since it provides abundance data.The reliance on morphological methods has limited our perception of the aquatic biodiversity in response to anthropogenic stressors, thereby providing inaccurate information for appropriate design and management of stormwater ponds; these drawbacks can be overcome by DNA metabarcoding. Synthesis and applications. The results indicate that DNA metabarcoding is a useful tool in identifying species, especially Diptera, which are difficult to determine. Application of DNA metabarcoding greatly increases the number of species identified at each sampling site, thereby providing a more accurate information regarding the way the ponds function and how they are affected by management. OPEN PRACTICES: This article has earned an Open Data Badge for making publicly available the digitally-shareable data necessary to reproduce the reported results. The data is available at https://www.ebi.ac.uk/ena/data/view/PRJEB30841.

Temporal and Environmental Factors Driving Vibrio Vulnificus and V. Parahaemolyticus Populations and Their Associations With Harmful Algal Blooms in South Carolina Detention Ponds and Receiving Tidal Creeks.

Incidences of harmful algal blooms (HABs) and Vibrio infections have increased over recent decades. Numerous studies have tried to identify environmental factors driving HABs and pathogenic Vibrio populations separately. Few have considered the two simultaneously, though emerging evidence suggests that algal blooms enhance Vibrio growth and survival. This study examined various physical, nutrient, and temporal factors associated with incidences of HABs, V. vulnificus, and V. parahaemolyticus in South Carolina coastal stormwater detention ponds, managed systems where HABs often proliferate, and their receiving tidal creek waters. Five blooms occurred during the study (2008-2009): two during relatively warmer months (an August 2008 cyanobacteria bloom and a November 2008 dinoflagellate bloom) followed by increases in both Vibrio species and V. parahaemolyticus, respectively, and three during cooler months (December 2008 through February 2009) caused by dinoflagellates and euglenophytes that were not associated with marked changes in Vibrio abundances. Vibrio concentrations were positively and significantly associated with temperature and dissolved organic matter, dinoflagellate blooms, negatively and significantly associated with suspended solids, but not significantly correlated with chlorophyll or nitrogen. While more research involving longer time series is needed to increase robustness, findings herein suggest that certain HAB species may augment Vibrio occurrences during warmer months.

Monitoring water quality in Toronto's urban stormwater ponds: Assessing participation rates and data quality of water sampling by citizen scientists in the FreshWater Watch.

From 2013 to 2015, citizen scientist volunteers in Toronto, Canada were trained to collect and analyze water quality in urban stormwater ponds. This volunteer sampling was part of the research program, FreshWater Watch (FWW), which aimed to standardize urban water sampling efforts from around the globe. We held training sessions for new volunteers twice yearly and trained a total of 111 volunteers. Over the course of project, ~30% of volunteers participated by collecting water quality data after the training session with 124 individual sampling events at 29 unique locations in Toronto, Canada. A few highly engaged volunteers were most active, with 50% of the samples collected by 5% of trainees. Stormwater ponds generally have poor water quality demonstrated by elevated phosphate concentrations (~30µg/L), nitrate (~427µg/L), and turbidity relative to Canadian water quality standards. Compared to other urban waterbodies in the global program, nutrient concentrations in Toronto's urban stormwater ponds were lower, while turbidity was not markedly different. Toronto FWW (FWW-TO) data was comparable to that measured by standard lab analyses and matched results from previous studies of stormwater ponds in Toronto. Combining observational and chemical data acquired by citizen scientists, macrophyte dominated ponds had lower phosphate concentrations while phytoplankton dominated ponds had lower nitrate concentrations, which indicates a potentially important and unstudied role of internal biogeochemical processes on pond nutrient dynamics. This experience in the FWW demonstrates the capabilities and constraints of citizen science when applied to water quality sampling. While analytical limits on in-field analyses produce higher uncertainty in water quality measurements of individual sites, rapid data collection is possible but depends on the motivation and engagement of the group of volunteers. Ongoing efforts in citizen science will thus need to address sampling effort and analytical limits to fully realize the potential value of engaging citizen scientists in water quality sampling.