SFS Annual Meeting

6/04/2024  |   10:30 - 10:45   |  Independence Ballroom A

Assessing Stream Vulnerability to Road Salt Application in Philadelphia Road salt application has led to salinization of freshwater rivers and streams which has negative impacts for ecosystem health. To understand stream vulnerability to road salt application, it is necessary to quantify the mass and distribution of salt and transit time distributions across a range of watersheds. Urban watersheds are likely to be highly susceptible to road-salt induced salinization; however, transit times in urban watersheds remain understudied. One step towards better quantification of transit times is estimating the amount of salt that enters from groundwater storage versus rapidly enters the stream via runoff. To quantify this, we performed a baseflow separation using an end member mixing model with measured stream specific conductance data and precipitation specific conductance data for three nested watersheds. Baseflow separation was performed on non-winter data to avoid seasonal road salt runoff. Additionally, we used hysteresis to better understand the proximity of solute sources to our monitoring points. Contrary to previous results in less urbanized settings, we found no relationship between antecedent discharge and the fraction of new water entering streams. Similarly, we found no correlation between rainfall intensity and new water fraction or total precipitation. The higher portion of old water during low flow conditions could indicate an additional source of road salt stored in the subsurface in the non-winter seasons. However, the hysteresis results suggest that most of the salt in the stream is sourced from close by the monitoring points.

Ryan Frederiks (Primary Presenter/Author), Department of Earth and Environmental Science, Temple University, ryan.frederiks@temple.edu;

Laura Toran (Co-Presenter/Co-Author), Department of Earth and Environmental Science, Temple University, ltoran@temple.edu;

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6/04/2024  |   10:45 - 11:00   |  Independence Ballroom A

Drivers of spatial and temporal variability in conductivity in temperate, urban streams Freshwater salinization is a major concern in temperate climates where road salt is used to manage snow and ice on roadways. In urban and suburban areas, wastewater, weathering of infrastructure, and salting parking lots and sidewalks can also contribute to salt contamination, but little is known about how well these sources explain variation in stream conductivity, and what factors may mitigate high conductivity in streams. Over one year in the greater Boston Massachusetts area, we collected synoptic conductivity data seasonally at 100 stream sites reflecting a gradient of land use/cover and socio-demographics, and continuously at three streams with different levels of impervious cover. Synoptic baseflow conductivity was best explained by percent impervious cover and season (r2=0.47, p<0.001), with highest median conductivity in summer and early fall, but consistent relationships with impervious cover across seasons. At high impervious cover, watersheds with higher housing vacancy had lower conductivity, suggesting that resident salting behavior may affect conductivity. Street sweeping also modulated the relationship between impervious cover and conductivity, reducing the conductivity in denser urban areas. Continuous conductivity data varied with discharge; in the winter, stream conductivity spiked with increases in discharge, likely due to the influx of road salt into waterways. In the summer, higher discharge was linked with sharp decreases in conductivity, suggesting that storm flows dilute conductivity. Temporal patterns of conductivity highlight the interplay between road salt application, seasonal climate, and precipitation that can guide policy and management decisions under climate uncertainty.

Allison Roy (Primary Presenter/Author), U.S. Geological Survey, Massachusetts Cooperative Fish and Wildlife Research Unit, University of Massachusetts Amherst, aroy@eco.umass.edu;

Annika Quick (Co-Presenter/Co-Author), Virginia Wesleyan University, aquick@vwu.edu;

Rebecca Hale (Co-Presenter/Co-Author), Smithsonian Environmental Research Center, haler@si.edu;

Kristina Hopkins (Co-Presenter/Co-Author), U.S. Geological Survey, khopkins@usgs.gov;

Jack Soucie (Co-Presenter/Co-Author), University of Massachusetts Amherst, jsoucie22@gmail.com;

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6/04/2024  |   11:00 - 11:15   |  Independence Ballroom A

Community science monitoring can identify salt and thermal pollution, but making local change remains a challenge Since 2016, over 150 continuous monitoring stations that record conductivity, water temperature, and water depth have been deployed in small to medium streams draining forested to urban watersheds throughout the Delaware River Basin in collaboration with over 50 watershed groups and over 200 volunteers. Volunteers helped quantify spatial and temporal pollution gradients, including acute salt-pollution events associated with winter storms, long-term groundwater salt contamination, and summer thermal pollution. Finer spatial resolution of groundwater salt contamination and thermal pollution has been obtained in some watersheds via volunteer driven synoptic sampling events during baseflow conditions. Volunteers have provided essential day-to-day upkeep of the continuous stations, quality assurance/control, monitoring station troubleshooting, and independently executed synoptic monitoring efforts. This project demonstrated that high quality continuous and synoptic data can be acquired by volunteers, with professional support. However, subsequent steps of interpreting data and communicating findings to the public and to local decision makers challenge most volunteers. These challenges point to a need for collaborations between scientists and non-scientists, volunteers and professionals. To this end, groups in this network are collaboratively developing foundational documents to support community scientist involvement in data interpretation/analysis and engagement with local government. Groups are also developing materials such as brochures/hand-outs, infographics, and presentations for public outreach and advocacy efforts to inform lay audiences including local decision makers about issues, concerns, and possible solutions.

David Bressler (Primary Presenter/Author), Stroud Water Research Center, dbressler@stroudcenter.org;

John Jackson (Co-Presenter/Co-Author), Stroud Water Research Center, jkjackson@stroudcenter.org;

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6/04/2024  |   11:15 - 11:30   |  Independence Ballroom A

Pollution contribution of organic deposition in urban roads and parking lots Organic deposition from trees, bushes, and grass, falling on impervious surfaces like roads and parking lots, has been identified as a contributor of nutrient pollution in urban systems. However, studies regularly use laboratory-based leachate tests or compare the overlap of tree cover and impervious surface area with nutrient concentrations in outflows at a catchment or sub-catchment level to assess the contribution of organic deposition to urban stormwater pollution. Few studies have assessed the nutrient contribution directly from organic buildup on urban impervious surfaces. To address this knowledge gap, samples of organic debris were collected from curbs at six road and six parking lot sites and transferred to twelve concrete channels. Water from a rainwater tank was then run through the channels at 1.5 L/min with samples taken at 0, 5, 15, 30 and 60 minutes. Samples were then analyzed for total and dissolved nitrogen and phosphorus, organic and inorganic carbon and suspended solids. Sampling was repeated 5 times over an 8-week period. A first flush effect was seen for all analytes with concentrations dropping to background levels after 5-15 minutes. Analyte concentrations were not significantly different between roads and parking lots for most analytes. Overall, pollutant concentrations were lower, compared to other studies, indicating that other study methods may over-estimate stormwater pollution from organic deposition in urban systems. These findings will assist in more accurately defining the pollution contribution of organic deposition in urban catchments and assist urban managers in determining effective street sweeping regimes.

Joseph O'Connell (Primary Presenter/Author), Centre for Applied Water Science, University of Canberra, joseph.oconnell@canberra.edu.au;

Fiona Dyer (Co-Presenter/Co-Author), Centre for Applied Water Science, University of Canberra, fiona.dyer@canberra.edu.au;

Jurian Hoogewerff (Co-Presenter/Co-Author), University Of Canberra, Jurian.Hoogewerff@canberra.edu.au;

Rod Ubrihien (Co-Presenter/Co-Author), Centre for Applied Water Science, University of Canberra, Rod. Ubrihien@canberra.edu.au;

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6/04/2024  |   11:30 - 11:45   |  Independence Ballroom A

WATER QUALITY OF STORM WATER MANAGEMENT PONDS: A TEMPORAL AND SPATIAL CONSIDERATION Storm water management (SWM) ponds are engineered structures to retain and slowly release storm waters to reduce erosion and water quality issues in urban streams and rivers. The SWM ponds collect runoff, including associated nutrients and contaminants (e.g. road de-icing salt), from roadways and other impervious areas. Although typically not their primary function, SWM ponds also become important focal points for biodiversity within urban settings, linking aquatic and terrestrial ecosystems. We sampled 50 SWM ponds in Brampton, Canada during summer 2022 and approximately 50% were resampled during 2023, to study their water quality and biological composition relative to their design and landscape features. Water quality was assessed through: monthly vertical profiles of temperature, conductivity, dissolved oxygen (DO), and turbidity; water chemistry was sampled near surface and below stratification; and some ponds were monitored via data loggers measuring temperature, conductivity and DO. Ponds greater than 2m in depth were typically stratified through a combination of thermal and salinity conditions, and these ponds were frequently anoxic below stratification. Pond epilimnia could alternate between supersaturation of DO during daytime to anoxia during nighttime. Surface waters showed a wide variation in chemical conditions, including chloride and nutrients. Most exceeded chronic and some exceeded acute federal guidelines for chloride concentrations. Hypolimnetic conditions showed highly elevated levels of chloride, phosphorus, and some metals, as a consequence of stratification and anoxia. Water discharged from these ponds may represent multiple stressors for streams, and contribute to cumulative effects within urban areas.

Donald Jackson (Primary Presenter/Author), University of Toronto, don.jackson@utoronto.ca;

Charlie Loewen (Co-Presenter/Co-Author), Iowa State University, cloewen@IASTATE.EDU;

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6/04/2024  |   11:45 - 12:00   |  Independence Ballroom A

URBAN BEAVER VS. STORMWATER PONDS: VARIATIONS IN IMPACT ON DISSOLVED ORGANIC MATTER QUANTITY AND QUALITY Nutrient-rich runoff from urban watersheds is known to increase productivity in locations of hydrologic retention on the urban landscape, such as stormwater ponds. However, urban beaver ponds are also prevalent in some urban systems, and it is unclear if beaver ponds have the same response. We measured the quantity, source, and bioavailability of dissolved organic matter (DOM) across stormwater and beaver ponds in Atlanta, GA, in 2021. Dissolved organic carbon concentrations increase from inflow to outflow of stormwater ponds, but beaver pond did not show a change in concentration. Effects of pond type (stormwater vs. beaver) were greater than other potential controls on concentration, including flow and season. Specific ultraviolet absorbance at 254 nm behaved similarly between pond types, shifting towards more aromatic carbon in pond outflow. Beaver and stormwater ponds had similar ranges in DOM bioavailability, assessed through dark bottle incubations, in summer; both pond types had less bioavailable DOM in autumn. Overall, beaver and stormwater ponds have similar impacts on aromaticity and bioavailability of DOM, but only stormwater ponds increased dissolved organic carbon concentrations. This suggests that urban beaver ponds can help retain water on the urban landscape similar to stormwater ponds, but without similar increases in the export of bioavailable carbon.

Sarah Ledford (Primary Presenter/Author), Georgia State University, sledford@gsu.edu;

Julian Sheppy (Co-Presenter/Co-Author), Southern Cross University, j.shepp16@gmail.com;

Elizabeth Sudduth (Co-Presenter/Co-Author), Georgia Gwinnett College, esudduth@ggc.edu;

Sandra Clinton (Co-Presenter/Co-Author), Department of Geography and Earth Sciences, University of North Carolina Charlotte, sclinto1@uncc.edu;

Diego Riveros-Iregui (Co-Presenter/Co-Author), University of North Carolina, diegori@unc.edu;

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