Effects Of Road Salt Research Articles

The effect of road salt (NaCl) treatment on the hatching success of Daphnia magna and Thamnocephalus platyurus

Salinization is an emerging problem for freshwater biodiversity. Road salt treatment results in salinization of local freshwater, influencing its entire ecosystem throughout the year. The present study examines the impact of road salt on the hatching success of two zooplankton species, Daphnia magna and Thamnocephalus platyurus, using pure laboratory lines from MicroBioTest. Hatching success was determined without incubation (T0) and after 3, 7 and 28 days of incubation at 5°C (T3, T7 and T28, respectively), at different NaCl concentrations. The low-temperature incubation was intended to simulate winter conditions - 5°C corresponds to the water temperature at the bottom of the ponds during winter in a temperate climate. The number of hatchings decreased with increasing NaCl concentration for T. platyurus, and decreased rapidly after a crucial value of 7 600 mg NaCl/L for D. magna. At the second hatching (eggs washed after first incubation and put into standard freshwater), D. magna demonstrated a low hatching rate regardless of NaCl concentration, while most T. platyurus hatchings were observed at the highest NaCl concentration; hence, the highest (15 200 mg/L) and lowest (1 900 mg/L) NaCl concentrations resulted in similar total hatching for the two species. The incubation time for three and seven days in NaCl at 5°C had no significant impact on hatching success; however, T28 resulted in significantly lower hatching success at all NaCl concentrations and controls. No significant differences in hatching success were noted if the eggs were first washed after incubation in NaCl and then put into the standard freshwater for hatching.

The effects of road salt (NaCl), predation, and competition on the growth and community interactions of spotted salamanders (Ambystoma maculatum) and wood frogs (Lithobates sylvaticus)

Road deicing salts are frequently used in northern regions of the world during the winter and early spring months. As a result, a significant portion of road runoff into surrounding aquatic habitats contains road deicing salts. Previous studies found road salt contaminations in vernal pools that pond-breeding amphibians commonly use, including spotted salamanders (Ambystoma maculatum) and wood frogs (Lithobates sylvaticus). Studies have examined the impact of road salt on both amphibian species, but to our knowledge no previous studies have examined how road salt impacts the interspecific competition between both amphibians. We hypothesized that road salt would negatively impact growth and survivorship of both amphibian species. During the spring and summer of 2017, we conducted an outdoor mesocosm experiment in which we created eight experimental conditions with three main factors: presence/absence of NaCl (1000 mg/L Cl−), presence/absence of interspecific competition between the two amphibian species (A. maculatum and L. sylvaticus), and presence/absence of predatory dragonfly larvae (Family Libellulidae). Our experiment revealed that salt delayed hatching and increased deformity in spotted salamander hatchlings. Additionally, salt reduced salamander survivorship by 62% and frog survivorship by 30%. Wood frog tadpoles and road salt interacted to diminish salamander survivorship a further 80% beyond salt alone, likely through an increase in interspecific competition. Road salt increased the larval period of salamanders and decreased the proportion metamorphosed by the end of the experiment. Dragonfly larvae reduced salamander survivorship by 35%, whereas they increased wood frog tadpole development rates. Dragonfly larvae and salt interacted to alter tadpole denticle size, with salt negating the impact of dragonfly larvae. Thus, we found that salt interfered with aquatic predatory chemical cues. Overall, the results of this study suggest that management strategies should be implemented in order to reduce the impact of road salts on freshwater aquatic ecosystems.

The Effects of Road Salt (Nacl), Predation, and Competition on the Growth and Community Interactions of Spotted Salamanders (Ambystoma Maculatum) and Wood Frogs (Lithobates Sylvaticus)

The Effects of Road Salt (Nacl), Predation, and Competition on the Growth and Community Interactions of Spotted Salamanders (Ambystoma Maculatum) and Wood Frogs (Lithobates Sylvaticus)

Relative Toxicity and Sublethal Effects of NaCl and Energy-Related Saline Wastewaters on Prairie Amphibians

Increasing salinity in freshwater environments is a growing problem due both to the negative influences of salts on ecosystems and their accumulation and persistence in environments. Two major sources of increased salinity from sodium chloride salts (NaCl) are saline wastewaters co-produced during energy production (herein, wastewaters) and road salts. Effects of road salts have received more attention, but legacy contamination from wastewaters is widespread in some regions and spills still occur. Amphibians are sensitive to contaminants, including NaCl, because of their porous skin and osmoregulatory adaptations to freshwater. However, similarities and differences between effects of wastewaters and road salts have not been investigated. Therefore, we investigated the relative influence of wastewaters and NaCl at equivalent concentrations of chloride on three larval amphibian species that occur in areas with increased salinity. We determined acute toxicity and growth effects on Boreal Chorus Frogs (Pseudacris maculata), Northern Leopard Frogs (Rana pipiens), and Barred Tiger Salamanders (Ambystoma mavortium). We posited that wastewaters would have additive effects on amphibians compared to NaCl because wastewaters often have additional toxic heavy metals and other contaminants. For NaCl, toxicity was higher for frogs than the salamander. Toxicity of wastewaters was also similar between chorus and leopard frogs. Only chorus frog survival was lower when exposed to wastewater compared to NaCl. Mass and length of leopard and chorus frog larvae decreased with increasing salinity after only 96 hours of exposure but did not for tiger salamanders. Size of leopard frogs was lower when exposed to NaCl compared to wastewater. However, growth effects were similar between wastewater and NaCl for chorus frogs. Taken together, our results suggest that previous studies on effects of road salt could inform future studies and management of wastewater-contaminated ecosystems, and vice versa. Nevertheless, effects of road salts and wastewaters may be context-, species-, and trait-specific and require further investigations. The negative influence of salts on imperiled amphibians underscores the need to restore landscapes with increased salinity and reduce future salinization of freshwater ecosystems.

Using wood chips for the protection of plants and soil from the harmful effects of road salt

In this study, the use of a new system made of natural wood absorbers (Salix viminalis) is proposed as a tool to protect plants, groundwater and soil from the adverse effects of de-icing salt. The toxic effects of road de-icing salt on soils, groundwater and plant growth have concerned environmental scientists, especially ecologists, for decades and have already been the subject of many studies. In terms of both time and cost, sodium chloride is widely regarded as the most effective chemical for de-icing roads and pavements. The protection of roadside plants is mainly achieved by using physical barriers with a limited capacity to retain road salt. Willow chips were packed into three systems: separated micro-columns, separated micro-columns with retention cups, and a monolayer column. Each system eliminated some of the salt from a brine solution such that only low-salinity water penetrated into the soil. The efficiency of road salt uptake varied from 31–95% depending on the system. The efficiency of the system was determined based on the salt content measured in the absorber collected after winter. Soil contamination by de-icing salt and the migration of different ions in groundwater were beyond the scope of this study.

Effects of road salt on a free-living trematode infectious stage

Many temperate freshwater habitats are at risk for contamination by run-off associated with the application of road de-icing salts. Elevated salinity can have various detrimental effects on freshwater organisms, including greater susceptibility to infection by parasites and pathogens. However, to better understand the net effects of road salt exposure on host-parasite dynamics, it is necessary to consider the impacts on free-living parasite infectious stages, such as the motile aquatic cercariae of trematodes. Here, we examined the longevity and activity of cercariae from four different freshwater trematodes (Ribeiroia ondatrae, Echinostoma sp., Cephalogonimus sp. and an unidentified strigeid-type) that were exposed to road salt at five different environmentally relevant concentrations (160, 360, 560, 760 and 960 mg/ml of sodium chloride). Exposure to road salt had minimal detrimental effects, with cercariae activity and survival often greatest at intermediate concentrations. Only the cercariae of Cephalogonimus sp. showed reduced longevity at the highest salt concentration, with those of both R. ondatrae and the unidentified strigeid-type exhibiting diminished activity, indicating interspecific variation in response. Importantly, cercariae seem to be relatively unaffected by salt concentrations known to increase infection susceptibility in some of their hosts. More studies will be needed to examine this potential dichotomy in road salt effects between hosts and trematodes, including influences on parasite infectivity.

Effects of road salt on microbial communities: Halophiles as biomarkers of road salt pollution.

Increased use of salting to de-ice roadways, especially in urban areas, is leading to elevated salinity levels in soil as well as surface- and ground water. This salt pollution may cause long-term ecological changes to soil and aquatic microbial communities. In this study, we examined the impact on microbial communities in soils exposed to urban road salt runoff using both culturing and 16S amplicon sequencing. Both methods showed an increase in halophilic Bacteria and Archaea in samples from road salt-exposed areas and suggested that halophiles are becoming persistent members of microbial communities in urban, road salt-impacted soils. Since salt is a pollutant that can accumulate in soils over time, it is critical to begin assessing its impact on the environment immediately. Toward this goal, we have developed a facile semi-quantitative assay utilizing halophilic microbes as biomarkers to evaluate on-going salt pollution of soils.

Timing is everything: Pulsed versus constant exposures in assessing effects of road salt on aquatic organisms.

Timing is everything: Pulsed versus constant exposures in assessing effects of road salt on aquatic organisms.

Effects of road salt on larval amphibian susceptibility to parasitism through behavior and immunocompetence

Large quantities of road salts are used for de-icing in temperate climates but often leach into aquatic ecosystems where they can cause harm to inhabitants, including reduced growth and survival. However, the implications of road salt exposure for aquatic animal susceptibility to pathogens and parasites have not yet been examined even though infectious diseases can significantly contribute to wildlife population declines. Through a field survey, we found a range of NaCl concentrations (50–560mg/L) in ponds known to contain larval amphibians, with lower levels found in sites close to gravel- rather than hard-surfaced roads. We then investigated how chronic exposure to environmentally-realistic levels of road salt (up to 1140mg/L) affected susceptibility to infection by trematode parasites (helminths) in larval stages of two amphibian species (Lithobates sylvaticus − wood frogs, and L. pipiens − northern leopard frogs) by considering effects on host anti-parasite behavior and white blood cell profiles. Wood frogs exposed to road salt had higher parasite loads, and also exhibited reduced anti-parasite behavior in these conditions. In contrast, infection intensity in northern leopard frogs had a non-monotonic response to road salts even though lymphocytes were only elevated at the highest concentration. Our results indicate the potential for chronic road salt exposure to affect larval amphibian susceptibility to pathogenic parasites through alterations of behavior and immunocompetence, with further studies needed at higher concentrations, as well as that of road salts on free-living parasite infectious stages.

Contribution of mineral dust sources to street side ambient and suspension PM10 samples

The aim of this study was to determine the relative contributions of mineral dust sources, particularly pavement wear and traction sanding in the PM10 samples collected from 1) street side ambient air and 2) street dust suspension emission samples. The study was conducted between autumn 2011 and spring 2012 at Suurmetsäntie in Helsinki, Finland. The results showed that dust from pavement aggregates was the largest source during spring, accounting for 40–50 percent of the particulate matter in the air and suspension samples. Based on studies on formation of dust, major source of the dust from pavement aggregates is the wear by studded tyres. Traction sanding (1–5.6 mm wet sieved crushed stone) and road salting (NaCl) were applied frequently during the winter 2011/2012. Sanding material explained about 25 percent of the street dust in the air and suspension samples. Traction sanding is estimated to account for approximately few percent of the pavement dust via “the sandpaper effect”. Effect of road salt was few percent in the samples. The source contributions from pavement and traction sanding observed in spring 2012 at Suurmetsäntie are similar to what has been estimated in a previous study conducted in the early 2000s in Finland. The general perception in Finland has been that traction sanding is the main source of airborne street dust. Studies conducted in 2000s and the results of this study, however, indicate that traction sanding has been an important but not the main source of dust in PM10 even in winters with extensive use of sanding for traction control.

Cultural meromixis: Effects of road salt on the chemical stratification of an urban kettle lake

Saline runoff from application of road salt deicers has the potential to create persistent density gradients in urban freshwater lakes, resulting in significant changes to physical mixing and biogeochemical cycling. In this study, the seasonal influence of road salt influx on the geochemical cycling of a small, urban kettle lake is examined. Water column samples were collected approximately twice per month for fifteen months and analyzed for temperature, pH, conductivity, major ions, nutrients and redox-sensitive solutes. The lake water column was redox-stratified with high concentrations of dissolved Mn(II), Fe(II), ammonium, phosphate and, during some periods, sulfide and methane in the hypolimnion. Bottom water anoxia was persistent throughout the entire sampling period. Concentrations of sodium and chloride, which correlated strongly with conductivity, were over a hundred times greater compared with levels in nearby rural lakes. Conductivity, chloride and calculated density profiles indicated the presence of a pycnocline at ~9m depth that persisted throughout the sampling period. The chemical data demonstrate that road salt input has caused the lake to become meromictic, with a complete lack of fall and spring turnover.

Effects of road salts on groundwater and surface water dynamics of sodium and chloride in an urban restored stream

Road salts are a growing environmental concern in urban watersheds. We examined groundwater (GW) and surface water (SW) dynamics of Na+ and Cl− in Minebank Run (MBR), an urban stream in Maryland, USA. We observed an increasing salinity trend in this restored stream. Current baseflow salinity does not exceed water quality recommendations, but rapid “first flush” storm flow was approximately one-third that of seawater. Comparisons between the upstream and downstream study reaches suggest that a major interstate highway is the primary road salt source. A heavily used road parallels most of MBR and was an additional source to GW concentrations, especially the downstream right bank. A baseflow synoptic survey identified zones of increased salinity. Downstream piezometer wells exhibited increases in salt concentrations and there was evidence that Na+ is exchanging Ca2+ and Mg2+ on soils. SW salt concentrations were generally elevated above GW concentrations. Salinity levels persisted at MBR throughout the year and were above background levels at Bynum Run, a nearby reference stream not bisected by a major highway, suggesting that GW is a long-term reservoir for accumulating road salts. Chronic salinity levels may be high enough to damage vegetation and salinity peaks could impact other biota. Beneficial uses and green infrastructure investments may be at risk from salinity driven degradation. Therefore, road salt may represent an environmental risk that could affect aquatic biota and limit the effectiveness of costly resource management and restoration efforts.

Hydrogeochemistry of the Catskill Mountains of New York

Major ion chemistry of Catskill region groundwater is characterized on the basis of 207 analyses compiled from three sources, including a web-based U.S. Geological Survey database, state agency regulatory compliance data, and sampling of trailside springs performed by the authors. All samples were analyzed for the complete set of major ions, including calcium, magnesium, sodium, potassium, bicarbonate, chloride, sulfate, and nitrate. Groundwater in pristine, high-elevation areas of the Catskill Peaks was found to be predominantly of calcium bicarbonate, calcium sulfate, or calcium bicarbonate-sulfate types, with relatively low ionic strength. Groundwater at lower elevations along the margins of the region or in valley bottoms was predominantly of sodium-chloride or sodium-bicarbonate types, showing the effects of road salt and other local pollution sources. Nitrate and sulfate enrichment attributable to regional air pollution sources were most evident in the high-elevation spring samples, owing to the generally low concentrations of other major ions. Trailside springs appear to be viable low-cost sources for obtaining samples representative of groundwater, especially in remote and inaccessible areas of the Catskill forest preserve.

Effects of Road Salts on Seasonal Wetlands: Poor Prey Performance May Compromise Growth of Predatory Salamanders

Road deicing agents that enter wetlands can affect amphibians both directly via their toxic effects and indirectly by altering food web interactions. We conducted experiments to determine whether larvae of the spotted salamander (Ambystoma maculatum) are more strongly influenced by direct versus indirect effects of salt concentration. Using outdoor mesocosms, we exposed salamanders and their prey to experimental salinities that were representative of values reported from salt contaminated breeding sites in North America. Increasing salinity depressed salamander growth but did not affect survival. Cladocerans were numerical dominants in samples taken 2 weeks after the experiment began, and markedly declined with increasing salinity. The number of cladocerans and total number of all invertebrates on this date were positively correlated with the mean mass of salamanders at the termination of the experiment. In a laboratory experiment where food was supplied in excess, increasing salinity did not affect the growth or survival of spotted salamanders that were chronically exposed to salinities that paralleled those in the mesocosm experiment. Our results suggest that spotted salamander larvae are more salt-tolerant than their prey, and that salamander growth may be compromised via indirect effects when breeding sites experience moderate salt contamination (i.e., < 1,000 mg L−1 of salts).

Effects of Road Salt on Connecticut's Groundwater: A Statewide Centennial Perspective

This study examined the extent to which development and road salting has affected Connecticut's groundwater. We gathered water quality data from different time periods between 1894 and the present and analyzed the data using maps generated with ESRI ArcGIS. Historical reports illustrate a statewide baseline trend of decreasing chloride concentration northward across the State (average, 2 ppm). Since then, statewide chloride concentrations in ground water have increased by more than an order of magnitude on average. Analysis indicates spatial correlation between chloride impacts and major roadways. Furthermore, increases in statewide chloride concentration parallel increases in road salt application. Projected trends suggest that statewide baseline concentrations will increase by an amount equal to five times background levels between the present and the year 2030. The analytical process outlined herein can be readily applied to any region to investigate salt impacts on large spatial and temporal scales.

The Effects of Road Salt on Stream Water Chemistry in Two Small Forested Watersheds, Catoctin Mountain, Maryland, USA

The Hauver Branch and Hunting Creek watersheds in Catoctin Mountain, Maryland, USA, are small rural watersheds that receive road salt during the winter. Base cation evidence of road salt application in stream water disappears by approximately September for Hauver Branch, but never disappears for Hunting Creek. The fraction of the precipitation-corrected watershed fluxes of both Mg2+ and Ca2+ attributable to cation exchange associated with road salt Na+ inputs are 14 and 19 % for Hauver Branch and Hunting Creek, respectively. The percentage of divalent cations in stream waters resulting from road salt application is calculated using the watershed chemical weathering Na+/SiO2 molar ratio. Calculation of a representative chemical weathering Na+/SiO2 molar ratio may be problematic with spatially variable bedrock, and/or inputs from water softeners, septic systems, and wastewater treatment plants. Therefore, investigations of small forested rural watersheds offer insights into road salt dynamics that may be lost at larger scales and/or with increased urbanization. The quantities of road salt application to the Hauver Branch and Hunting Creek watersheds are 3.3 and 11 t km−2 year−1, respectively. The per-lane-length-normalized road salt application rates for the Hauver Branch and Hunting Creek watersheds are 10 and 22 t lane−1 km−1 year−1, respectively. These per-lane-length-normalized road salt application rates are relatively large compared to more urbanized watersheds located north of the study site where the application rates are reported by municipalities. These findings may indicate that road and highway administrations may underestimate their rates of road salt application.

Causes of toxicity to Hyalella azteca in a stormwater management facility receiving highway runoff and snowmelt. Part II: Salts, nutrients, and water quality

The Terraview–Willowfield Stormwater Management Facility (TWSMF) features a tandem of stormwater management ponds, which receive inputs of multiple contaminants from highway and residential runoff. Previous research determined that benthic communities in the ponds were impacted by poor habitat quality, due to elevated sediment concentrations of metals and polycyclic aromatic hydrocarbons (PAHS), and salinity in the overlying water, but did not address seasonal changes, including those caused by the influx of contaminants with the snowmelt. In order to address this issue, water and sediment samples were collected from the TWSMF during the fall and spring, and four-week sediment toxicity tests were conducted with Hyalella azteca. The effects of metals and PAHs are discussed in a companion paper; the effects of road salt, nutrients, and water quality are discussed here. After exposure to fall samples, survival of Hyalella was reduced (64–74% of controls) at three out of four sites, but growth was not negatively affected. After exposure to spring samples, survival was 0–75% of controls at the two sites furthest downstream, and growth was significantly lower in four out of five sites when comparing Hyalella exposed to site water overlying site sediment versus control water overlying site sediment. Toxicity appeared to be related to chloride concentrations: little or no toxicity occurred in fall samples (200mgCl−/L), and significant effects on survival and growth occurred in spring samples above 1550mgCl−/L and 380mgCl−/L, respectively. Sodium chloride toxicity tests showed similar results: four-week LC50s and EC25s (growth) were 1200 and 420mgCl−/L, respectively. Although water quality and nutrients were associated with effects observed in the TWSMF, chloride from road salt was the primary cause of toxicity in this study. Chloride persists during much of the year at concentrations representing a significant threat to benthic communities in the TWSMF.

The effects of road salt on larval life history traits and behavior in Rana temporaria

The effects of road salt on larval life history traits and behavior in <I>Rana temporaria</I>

Periphyton response to simulated nonpoint source pollution: local over regional control

We investigated functional and structural responses of periphyton communities to simulated nonpoint source (NPS) pollution over a 2-year period. Periphyton communities were examined in three unique but hydrologically connected habitats in the lower Muskegon River: river, wetland, and lake. Our study addressed several major questions: (1) what are the effects of nonpoint source pollutants on periphyton structure and function, (2) to what degree do environmental conditions, including the pollutant delivery system and hydrologic conditions, affect periphyton response, and (3) do periphyton communities show synchronous responses to nonpoint source pollution? Nutrients were added over a 21-day period in each of the four seasons over 2 years. The effect of road salt on metabolism was evaluated in the winter and spring seasons in the river habitat only. In general, the periphyton community showed complex responses to the NPS amendments, but there was little evidence of nutrient limitation in this system based on community structure, biomass accrual, metabolism, or alkaline phosphatase activity. This result was unexpected given the relatively low ambient concentrations of phosphorus. We discuss the possibilities that nutrient delivery was ineffective or that herbivory and/or irradiance might have constrained periphyton growth, but ultimately conclude that our results suggest that periphyton communities in the lower Muskegon River watershed were (1) nutrient-replete, (2) tolerant of short-term salt additions, and (3) influenced more by local conditions (habitat) than by regional (watershed) factors. In systems where nonpoint source pollutant delivery is diffuse and hydrologic residence time is short, the influence of nonpoint source pollutants on periphyton may be either modest or too difficult to detect using traditional endpoints.

Effect of salt and urban water samples on bacterivory by the ciliate, Tetrahymena thermophila

The effect of road salt on the eating of bacteria or bacterivory by the ciliate, Tetrahymena thermophila, was followed in non-nutrient Osterhout's solution with Escherichia coli expressing green fluorescent protein. Bacterivory was impaired at between 0.025 and 0.050% w/v but the ciliates appeared to have normal morphologies and motilities, whereas at above 0.1%, bacterivory was blocked and many ciliates died. By contrast, E. coli remained viable, suggesting salt could alter predator–prey relationships in microbial communities. In nutrient medium, salt was not toxic and the ciliates grew. After growth in salt, ciliates consumed bacteria in 0.2% salt, indicating the salt acclimation of bacterivory. Bacteria and ciliates were added to urban creek samples to compare their capacity to support exogenous bacterivory. Even though samples were collected weekly for a year and be expected to have fluctuating salt levels as a result of deicing, all creek samples supported a similar level of bacterivory.