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Environmental impacts of road salt and alternatives in the New York City watershed

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... Sodium chloride concentrations from 0.5% to 2% (dry weight) have been shown to cause discoloration to severe leaf burn, defoliation, and plant death, and salt deposits on leaf surfaces can cause localized dehydration (Sucoff 1975b). Tolerance to sodium chloride for some vegetation, specifically pine seedlings, can be as low as 67.5 ppm in soils; the sodium chloride concentration in soil should be less than 100 ppm to allow the seed germination and root growth of grasses and wildflowers (Wegner and Yaggi 2001). Some woody and herbaceous species, however, tolerate up to 200 ppm of sodium chloride. ...
... Calcium magnesium acetate showed no negative impacts to soil, vegetation, and streams on the North Island of New Zealand where it was used for anti-icing and deicing; the high application costs were the principal disadvantage (Burkett and Gurr 2004). Calcium magnesium acetate works similarly to sodium chloride, but it can require 50% more by weight to achieve the same results (Wegner and Yaggi 2001) and is "slower acting and less effective in freezing rain, drier snowstorms, and light-traffic conditions" (Ramakrishna and Viraraghavan 2005). Other disadvantages of calcium magnesium acetate include air quality impacts, poor performance in thick accumulations of snow and ice, and poor performance in temperatures below 23°F (−5°C). ...
... Potassium acetate is generally used for anti-icing and performs quicker than calcium magnesium acetate at lower temperatures, but costs more (Wegner and Yaggi 2001). Few studies have been conducted to examine its environmental impacts (Wegner and Yaggi 2001). ...
Article
As chemicals are widely used for snow and ice control of highway and airfield pavements or air-crafts, recent years have seen increased concerns over their potentially detrimental effects on the surrounding environment. The abrasives used for winter operations on pavements are also a cause of environmental con-cerns. After some background information, this paper presents a review of the environmental impacts of chemicals used for snow and ice control, including those on: surface, ground, and drinking waters; soil; flora; and fauna. The paper provides a state-of-the-art survey of published work (with a focus on those in the last two decades) and examines mainly the impacts of abrasives, chlorides, acetates and formates, urea, gly-cols, and agro-based deicers. Finally, we conclude with a brief discussion of public perception of such impacts and best management practices (BMPs) to mitigate them.
... These elevated concentrations can cause localized leaf dehydration, leaf burn, defoliation, leaf necrosis, pines needle browning, twig dieback and eventually plant death (Sucoff 1975;Cekstere et al. 2008). In some cases, the sodium chloride concentration tolerance for vegetation can be as low as 67.5 mg/L in the soil, specifically for pine seedlings (Wegner and Yaggi 2001). However, the detrimental effects of chloride deicers on trees decrease with increasing distance from the roadside. ...
... For instance, grasses, ferns, maples, and oaks all have high tolerances to chloride deicers, while pines and sumacs near roadways will exhibit severe damage (Bryson and Barker 2002). The maximum sodium chloride concentration for seed germination and root growth of some grasses and wildflowers can be as low as 100 mg/L (Wegner and Yaggi 2001), while some herbaceous species can tolerate up to 200 mg/L of sodium chloride (TRB 1991). In addition, deciduous broadleaved shrubs are more tolerant to elevated chloride deicers than are evergreen needleleaved shrubs (Li et al. 2014). ...
... Moreover, when compared with sodium chloride, acetate-based deicers (calcium magnesium acetate and potassium acetate) can cause a higher mortality rate for the wood frog larvae in the 96-h acute toxicity test (Harless et al. 2011). Calcium magnesium acetate (CMA) performs similarly to sodium chloride in light to moderate snow, but is less effective in thick accumulation of snow and ice and at lower temperatures (Wegner and Yaggi 2001;Ramakrishna and Viraraghavan 2005). CMA can increase the biological oxygen demand (BOD) in soils and water bodies because of microbial decomposition (Findlay and Kelly 2011). ...
Chapter
As abrasives and deicer products are widely used for snow and ice control, the past decade has seen increased concerns over the detrimental impacts on the surrounding environment. Generally, these snow and ice control materials can cause impacts to air quality, water quality, soil, flora, fauna, and human health. The added cost of clean‐up and the paradigm shift from reactive to proactive snow and ice control strategies have resulted in growing use of chemicals instead of abrasives. Therefore, there is a need to better understand and assess the environmental impacts of deicers, in an effort to conduct sustainable winter road maintenance operations in an environmentally and fiscally responsible manner. This chapter will discuss relevant background information and provide a review of the environmental impacts of snow and ice control materials, including abrasives, chlorides, acetates and formates, glycols, urea, and agro‐based deicers, according to a survey of published work particularly those over the last two decades.
... It also has the potential for phosphorous enrichment of surface waters exposed to high concentrations of CMA from agricultural products. In addition, CMA costs 16 to 23 times more than sodium chloride (Wegner & Yaggi, 2001) Potassium Acetate (KA) Potassium acetate, like CMA, is less harmful to plants and animals, less corrosive to metals and concrete materials compared to sodium chloride. Inhalation of KA may cause mild irritation to the respiratory tract. ...
... As with NaCL and CMA, KA brings about temporary oxygen depletion in water. It costs 23 to 26 times more than sodium chloride (Wegner & Yaggi, 2001). ...
Article
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Snowstorms/ice storms cause (a) road deaths/ injuries/property damage (b) environmental damage from deicing salt/contaminant highway runoff (c) drinking water contamination from deicing salt-runoff, with potential implications for human health (d) lost revenue from road deaths/injuries/damages/salting highways and snow removal (e) productivity/ school attendance loss consequent to nonpassable roadways (f) salt-induced damage to roads/automobiles/wildlife/plants/birds/pets and (g) lack of access to emergency medical care. Stretches of intracity highways and important roads/bridges covered with a “ ” shaped, ventilator-fitted Plexiglas roof will keep roads snow/ice free. Plexiglas roofing would help eliminate the need for salting roads and snow removal. This would help alleviate environmental damage, groundwater contamination, and human health interactions, particularly salt intake and hypertension and other diseases. Roofed-roads would reduce rain-related accidents, help prevent corrosion of roads/bridges due to road-salt/rain/acid rain and water freeze/thaw-related road/bridge damage. Covered local roads and intracity highways would be a boon to commuters in icy/rainy road conditions.
... Direct effects of chloride on roadside vegetation—decreased leaf size, leaf chlorosis, leaf burn, and tissue death (Environment Canada and Health Canada 2001)—occur at concentrations as low as 30 mg/L (Godwin et al. 2003). Eventually, the chloride migrates into the groundwater, where the chloride concentration may exhibit a relatively linear relation to road-salt application rate or to the density of two-lane roads (Wegner and Yaggi, 2001). Chloride accumulation in soils and in groundwater subsequently raises the baseflow chloride concentrations in surface water bodies during the summer and leads to increases in the baseline salinity of surface waters (Rosenberry et al. 1999; Siver et al. 1996 ). ...
... Deicing salts have the potential to induce ion exchange causing acidification of surface waters and increasing the mobility of other metals (Löfgren 2001). Prolonged retention of chloride in streambeds reduces dissolved oxygen and can increase nutrient loading, leading to eutrophication (Hale and Groffman 2006; Wegner and Yaggi 2001). Elevated levels of chloride in streams result in the decrease of benthic diversity (Mayer et al. 1999to have lethal and sublethal effects on aquatic plants and invertebrates (Hart et al. 1991). ...
Article
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The application of road salts as deicing agents contributes to the anthropogenic loading of chloride (Cl−) on the environment. Using a 2D solute model, the potential of the unsaturated zone to serve as a reservoir and the mechanisms controlling the movement of Cl− were examined. Physical properties and initial pore-water Cl− concentrations were derived from an array of soil borings. Initial pore-water concentrations show the presence of a Cl− “slug” approximately 0.75m below the surface. Simulations show that within the unsaturated zone, Cl− transport is predominantly vertical, driven by molecular diffusion. After a 1-year simulation, a Cl− slug similar to the background observation was noted. While Cl− is retained in the unsaturated zone, a net loss of Cl− from the unsaturated zone was simulated for the first 10 years. In year 11, an equilibrium between the Cl− input and output is achieved. The presence of Cl− in the unsaturated zone becomes a long-term source of chloride to the groundwater, which eventually discharges into the surface water. Historically, surface water chemistry data support the continual discharge of chloride to the surface water in the area, further supporting the hypothesis that the unsaturated zone serves as a Cl− reservoir.
... Snow runoff containing salt can produce high sodium and chloride concentrations in ponds, lakes, and bays. (Wegner, 2001) This can cause fish kills and changes to water chemistry that can result in the colonization of wetlands by invasive species. "These species include cattails and phragmites, both of which can be indicators of degraded wetlands subject to excessive nutrient loading and/or salt contamination." ...
... "These species include cattails and phragmites, both of which can be indicators of degraded wetlands subject to excessive nutrient loading and/or salt contamination." (Wegner, 2001) In addition to investigating the influence of the highways on water quality I have identified land-uses within the watershed as sources that could contribute to a diminished water quality. ...
... For seed germination and root growth to occur for grasses and wildflowers, the NaCl concentration in soil should be less then 100 ppm. Some woody and herbaceous species, however, tolerate up to 200 ppm of NaCl (Wegner and Yaggi, 2001). In one study, chloride concentrations in soil near a Canadian highway were taken. ...
... Acetates have been extensively studied as alternatives to chloride-based products for snow and ice control. Environmental impacts are minimal with acetates, but due to funding limitations, the cost makes acetates infeasible for many agencies (Cheng and Guthrie, 1998;Vitaliano, 1992;Wegner and Yaggi, 2001;Fischel, 2001;Keating, 2001). Testing of soil, vegetation, and streams in the North Island of New Zealand where calcium magnesium acetate is used for both anti-icing and deicing has shown no negative impacts; however, the costliness of the product is its principal disadvantage (Burkett and Gurr, 2004). ...
... But there is a major problem with rust; extensive use of de-icing salts on bridges leads to corrosion of the reinforcement. 15 million tons of de-icing salts are used each year in the United States of America and 4 to 5 million tons in Canada [1]. When there is significant exposure to salt on the concrete surface, the alkaline protection to the steel can break down rapidly due to chloride attack and it may start to corrode; this can result in large and increasing portions of government budgets being spent to repair the concrete infrastructure. ...
Article
This paper examines the environmental conditions under which the time to cracking of concrete, due to pressure caused by rust production on the surface of steel bars, is short. To determine this time, volume compatibility is assumed, which allows for compaction of all materials affected by the pressure, including the rust itself. A fracture mechanics concept is also used to signal cover failure. The model reveals that time-to-cover-cracking is a function of the rust production and the strength of the system to resist the resulting pressure. It is found that the highest corrosion rates are towards the end of autumn and the beginning of spring, when humidity reaches relatively high values with moderate temperatures. On the other hand the highest resistance of the system to corrosion production is during summer, since the humidity is low. In addition, rust pressure drops during summer due to creep; water moves out of the concrete which also deforms, giving more space into which the rust can expand. Structures exposed to humid summers would suffer from high rust production and rapid cover spalling. The model can assist in the decision-making process to identify when a bridge is more likely to corrode, which could indicate that new materials, like fibre reinforced polymers might be the most suitable design solution despite their higher initial cost.
... There are several local highways running through the study area (Fig. 1a) and road salts are applied on the highways as a deicing agent during winter (Krabbenhoft, 1988;Bowser, 1992;Kenoyer and Bowser, 1992a). The most commonly used deicing salt in USA, including this area, is sodium chloride (NaCl; rock salt) because it is readily available, inexpensive, and effectively depresses the freezing point of water to melt ice (NRC, 1991;Keating, 2001;Wegner and Yaggi, 2004). Due to the influence of NaCl-deicers, some groundwaters and lakes located near the highways of the study area show higher Cl and Na levels than others (Bowser, 1992;Krabbenhoft, 1988;Kenoyer and Bowser, 1992a). ...
Article
Full-text available
The water chemistry data obtained from a sandy aquifer in the Trout Lake basin of northern Wisconsin, USA were reinvestigated in order to explain the chemical behavior of sodium concentration in groundwater. Monovalent cations such as sodium and potassium dissolved in groundwater generally remain within narrow concentration ranges. In contrast, calcium and magnesium concentrations show continuously increasing trends due to continuous weathering of aquifer materials, of which reactive minerals are dominated by sodic plagioclase. The similar trend observed in groundwaters contaminated with NaCl-deicer suggests that this unusual chemical behavior of monovalent cation is caused by cation exchange reactions. In other words, when Na ions are introduced into the groundwater system, only a minor fraction of the Na ion (∼5%) partitions into the aqueous phase, whereas the majority replaces divalent cations adsorbed on the exchangeable sites of the sediments. However, the cation exchange capacity (CEC) measured for the sandy sediment (∼4 meq/kg) is insufficient to cause the observed consistent Na concentration under a batch condition (stagnant groundwater with no molecular diffusion) of cation exchange. Results of transportive exchange calculations suggest that Na concentration can be effectively "buffered" as the NaCl-contaminated groundwater flows even when the CEC was very low (1 meq/kg) because flowing groundwater can interact with more cation exchange sites than that under stagnant conditions. It is also suggested that the buffering of Na concentration due to cation exchange can partly explain the "Ca-excess problem" that has been noted previously in the study area.
... To date, the ecohydrological simulations intentionally simplify some areas, by neglecting the activities of bacteria, fungi, and animals (including human management) and the constraints of soil chemistry, to focus on complexities of vegetation form and function. In its next step ecohydrology should address features of the urban environment, by simulating human activities such as stormwater management with the associated chemical constraints, such as road salt toxicity (Wegner and Yaggi, 2001) and the limits on sorption of urban metals (Davis et al., 2003). Rodriguez-Iturbe (2000; has identified a major application area for the new field as representing hydrologic control on ecological processes through simulation, where water may be a limiting factor due to scarcity or intermittent and unpredictable appearance. ...
Chapter
Full-text available
Urban and suburban development alters watershed imperviousness and connectivity, resulting in alterations to the hydrologic and hydraulic runoff response. Stormwater conveyance devices have been incorporated into most development to address the goal of floodwater removal for protection of life and property. Urban and suburban development laws generally consider the stormwater drainage system as part of the basic infrastructure and leave right of way and space to locate the component parts. Drainage systems are designed to protect life, enable vehicular access, extend pavement life cycle, control the volume and velocity of stormwater runoff along curbs and gutters, and convey stormwater runoff to natural or human constructed drainage ways and receiving waters. Engineering equations have been developed to design construction for optimal runoff behavior, such as timing, volume, and rate, into, through, and from conveyance devices. Design equations are also utilized for assessing the performance of constructed environments, to ascertain whether stormwater devices need rehabilitation or expansion. New frontiers in stormwater include model spatially distributed development that incorporates high-density elevation maps, radar rainfall, and details of remotely sensed infrastructure as well as ecological restoration simulation, including groundwater and river remediation for wildlife and recreation.
... En çok kullanılan kimyasallar CaCl 2 , MgCl 2 , CMA (Kalsiyum, Magnezyum, Asetat) ve NaCl'dür (Kuloğlu ve ark., 2005). Amerika Birleşik Devletlerinde buzlanmayı önlemek için yılda ortalama 15 milyon ton tuz kullanıldığı bilinmektedir (Wegner ve Yaggi, 2001). Yol kaplamalarına zarar veren NaCl tuzu, yol yüzeyinde soyulmalara neden olmaktadır. ...
Article
Full-text available
ZET Korozyon, metallerin bulunduğu ortamda kimyasal veya elektrokimyasal reaksiyonlar sonucunda bozulması ve zamanla metalik özelliğini kaybetmesidir. Karayollarında kullanılan işaret levhaları, elektrik direkleri, köprü elemanları, bariyerler ve trafik ışıkları gibi metalik alaşımlardan yapılan malzemelerin de asfalt beton içerisinde olmalarına rağmen zamanla korozyona uğradıkları bilinmektedir. Diğer taraftan karayollarında karla mücadele kapsamında yapılan tuzlama çalışmaları da bu metaller için ayrıca korozif ortam oluşturmaktadır. Bu çalışmada, asfalt beton içerisine konulan düşük karbon çeliğinin açık devre potansiyeli sekiz hafta boyunca ölçülmüş ve potansiyelin zamana bağlı olarak -650 mV'tan -690 mV'a doğru azaldığı tespit edilmiştir. Birinci hafta sonunda %3.5 NaCl çözeltisi içerisindeki metalin korozyon potansiyeli -734 mV'tan -774 mV 'a kaymıştır. 8. hafta sonunda elde edilen korozyon akım yoğunluğu 1. hafta sonunda elde edilen değerden yaklaşık 1.76 kat daha fazladır. Buna bağlı olarak elde edilen korozyon direnci de azalmış olup korozyon direnci 2240 ohm.cm 2 den 859 ohm.cm 2 değerine kadar düşmüştür. ABSTRACT :Corrosion is the degradation of the metals as a result of chemical and electrochemical reactions and the loss of their metallic properties in time. Metallic alloys used in highways, such as traffic signs, lamppost, parts of the bridge, barriers and traffic lights are also known to corrode over time, although they are in asphalt concrete. On the other hand, salting processes to prevent the icing on highways also create a corrosive environment for these metals. In this study, the corrosion potential of low carbon steel placed in asphalt concrete was measured during 8 weeks, and the open circuit potential has been found to decrease from -650 mV to -690 mV over time. At the end of the first week, corrosion potential of the metal in 3.5 % NaCl solution changed from -734 mV to -774 mV. Corrosion current density obtained at the end of the 8 th week is approximately 1.76 times more than the value obtained at the end of the 1 st week. Accordingly, corrosion resistance also reduced, and the corrosion resistance decreased from 2240 ohm.cm 2 to 859 ohm.cm 2 .
... Most vegetation damage occurs within 60 feet of the road and is greatest close to the pavement. Nonetheless, impacts have been observed up to 200 meters from treated roads as the contaminated water migrates (Wegner and Yaggi, 2001). Two mechanisms are primarily responsible for the impacts. ...
... Extensive use of deicing salts on bridges leads to corrosion of steel reinforcement in concrete. In the United States, 15 million tons of deicing salts are used each year and 4-5 million tons are used in Canada (Wegner and Yaggi 2001). Alternatives to salt exist, but their cost is very high and their environmental effects have not been fully evaluated. ...
Article
Vast governmental budgets are spent annually to face corrosion problems of steel reinforcement in concrete bridges attributable to the extensive use of deicing salts. Corrosion controls the lifetime of a bridge, which has two distinct periods. During the first period, chlorides diffuse through the cover. When sufficient chlorides are formed at the rebars, corrosion initiates. This marks the start of the second period, during which rust with higher volume to bare steel is produced. The rust puts pressure on the cover, which finally leads to cover spalling. In this paper, a model is developed to determine the time span of the second period. The model includes a volume compatibility condition that allows for the proper introduction of compaction of all materials that contribute to cover spalling, including the rust. A new condition for marking failure of the cover is also established, based on fracture mechanics and strain energies. Finally, a new formula is proposed for the rate of rust production, which allows for the constant rust production at early and nonlinear diffusion dependant rates at latter stages of corrosion. DOI: 10.1061/(ASCE)EM.1943-7889.0000215. (C) 2011 American Society of Civil Engineers.
... Eagleson intentionally simplifies some areas by neglecting the activities of bacteria, fungi and animals (including human management), and the constraints of soil chemistry, to focus on complexities of vegetation form and function. In the proposed application, ecohydrology should address features of the urban environment by simulating human activities such as storm-water management with the associated chemical constraints, such as road salt toxicity (Broecker et al., 1971;Wegner & Yaggi, 2001) and the limits on sorption of urban metals (Davis et al., 2003). Rodriguez-Iturbe (2000, 2003a has identified a major application area for the new field as representing hydrologic control on ecological processes through simulation where water may be a limiting factor due to scarcity or intermittent and unpredictable appearance. ...
Article
Full-text available
A framework for urban storm‐water management that moves beyond flood control to improve societal and ecological services will maximize the functions and benefits of water resources management. Theoretical constructs for such work originate from the integration of ecological engineering, ecohydrology and service learning paradigms. Implementation consists of simulating, monitoring and reporting how storm‐water design decisions to infiltrate or directly discharge runoff result in a complex set of linked adjustments to the dynamics of the water table, soil chemistry concentrations, plant stress/viability, terrestrial habitat, river loads/flows, and aquatic habitat patterns. Coordination of a socio‐ecological‐based urban storm‐water management programme is discussed using a case study in the Onondaga Creek watershed that drains through the City of Syracuse, NY, USA. In Onondaga Creek, service learning‐directed research gathered findings on the geomorphological characterization of a healthy stream, flood impacts of storm sewer separation, and channel stability with concrete removal. Unfortunately, linkages between systems will remain unexplored until the development of more tightly coupled channel‐watershed simulation models.
... In cases of sudden rainfall, insufficient personnel and work equipment do not make it possible to effectively prevent icing and snow accumulation on all roads. It is known that an average of 15 million tons of deicing salts is used annually to avoid icing on roads in the United States (Wegner 2001). The amount of deicing salt used in Turkey is estimated to be approximately 100 000 tons/year (Gürer 2014). ...
Article
Since ancient times, the closure of roads due to ice and snow accumulation is one of the most critical problems of highway transportation. There are two different approaches to prevent icing on the road: passive and active methods. In this study, the most efficient aggregate type and the asphalt mixture combination containing electrically conductive components was determined for electrically conductive asphalt pavements which are considered among the active anti-icing methods. For this purpose, a two-stage experimental study was carried out. In the first stage, asphalt concrete (CAC) specimens with 25 different aggregate and conductive component contents were produced and their properties such as volumetric resistivity, the temperature variations under constant (30 Volt) electrical direct current (DC), heating and cooling times and thermal conductivity were determined. Marshall asphalt design was also performed for three series (2.1; 4.1, and 4.3) for the best electrical and thermal conductivity properties in the second stage of the study. Volumetric resistivity tests were performed and temperature variations under constant voltage (30 V) were determined on the Marshall specimens. As a result of the study, environmentally friendly asphalt specimens with wearing layer having high electrical conductivity properties were developed. It was concluded that not only the conductive components but also the aggregate type was reasonably effective in terms of anti-icing performance and CAC specimens could exhibit behaviour close to traditional asphalt properties.
... Eagleson (2002) intentionally simplifies some areas, by neglecting the activities of bacteria, fungi, and animals (including human management) and the constraints of soil chemistry, to focus on complexities of vegetation form and function. In an alternative application, ecohydrology should address features of the urban environment, by simulating human activities such as stormwater management with the associated chemical constraints, such as road salt toxicity (Broecker et al., 1971;Wegner and Yaggi, 2001) and the limits on sorption of urban metals (Davis et al., 2003). Rodriguez-Iturbe (2000, 2003 has identified a major application area for the new field as representing hydrologic control on ecological processes through simulation where water may be a limiting factor due to scarcity or intermittent and unpredictable appearance. ...
... Ecological problems with sodium and chloride concentrations generally only occur in freshwater ecosystems, and include toxicity to plants, invertebrates, and fish. Human health concerns relate to the impacts of salt intake on hypertension (Howard and Haynes, 1993;Forman and Alexander, 1998;Wegner and Yaggi, 2001). ...
Chapter
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Abstract The chemistry of urban surface waters is influenced by natural biogeochemical processes that interact with the physical structures as well as the many activities and material inputs associated with dense human habitation. Concentrations of sediment, nitrogen, phosphorus, natural and novel organic compounds, metals, chloride, sulfate, calcium, magnesium, sodium, and potassium all change as the percentage of urbanized land increases. Unique urban chemistries result from many factors in the urban environment. They include high rates of watershed loading that increase with human activity and population density; more direct hydrologic pathways that route runoff and waste streams to surface waters via drainage systems and wastewater treatment plants; changes in the capacity of the landscape to retain and transform nutrient and organic matter inputs due to loss of vegetative cover and effective riparian zones; and alteration of streambed sediments, streambed form, and rates of bank erosion by increased peak flows. The conditions that create the uniquely urban biogeochemical cycles often lead to a degradation of water quality, but the extent of degradation can vary dramatically. Improvements in waste management, drainage systems, and stream restoration have been shown to reduce degradation or rehabilitate water quality in urban areas. The following is a review of available knowledge on global urban water chemistry and the chemical cycling in urban watersheds, which results in distinct urban biogeochemistry.
... When salt crystals are applied to paved surfaces and react with the snow and ice, they tend to dissociate into sodium (Na+) and chloride (Cl-) ions. Chloride can contaminate receiving water bodies and groundwater supplies through runoff or by infiltrating underlying aquifers (Wegner and Yaggi 2001;Heath and Belaval 2011) and has been shown to have impacts upon soils and roadside vegetation (Fay and Shi 2012). At the UNHSC, chloride concentrations in runoff from a 3.6-ha (9-acre), impervious parking lot subjected to standard winter maintenance practices have been measured as high as 5,000 mg=L. ...
Article
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This study presents the findings from research conducted at the University of New Hampshire Stormwater Center (UNHSC) which investigated porous pavements as a potential strategy for minimizing the use of deicing chemicals for winter maintenance. In cold regions, chloride is an integral component of winter maintenance and safe usage of transportation surfaces. Chloride-laden runoff from impervious surfaces threatens aquatic habitats, degrades drinking water supplies, and corrodes infrastructure. State and federal environmental agencies are beginning to regulate chloride usage through the implementation of total maximum daily loads (TMDLs). Parking surfaces in some watershed studies have been shown to be the single largest chloride source in storm-water runoff, in some instances contributing up to 50% of the total load. This study examined winter maintenance over two winters and 38 storms from 2006–2008. The study evaluated winter performance in response to deicing practices by measuring skid resistance, the degree of snow and ice cover, recoverable chloride mass, and effective salt loads. During and just after snowstorms, analysis of snow/ice cover and pavement skid resistance demonstrated that from 64 to 77% less salt was needed in order for a porous asphalt (PA) lot to maintain equivalent or better surface conditions as compared to a reference dense-mix asphalt (DMA) lot. Between snow storms, the lack of standing water on porous asphalt greatly reduced the frequency and mass of salt applications needed to control black ice. Although the DMA lot received a typical salt application that was four times greater, the annual median snow and ice surface cover for the PA lot was not significantly different (p ¼ 0.749, 95% confidence), and the annual median weighted skid resistance for the PA lot was 12% greater (p ¼ 0.061, 95% confidence). A companion study on the hydrologic and water quality performance reported that freeze-thaw was limited due to the well-drained nature designed into the system, and surface infiltration capacities remained in excess of 500 cm=h (200 in:=h), despite the fact that the maximum frost penetration depth observed was nearly 71 cm (28 in.). Porous pavements present one viable potential strategy for chloride reduction.
... When salt crystals are applied to paved surfaces and react with the snow and ice, they tend to dissociates into sodium (Na + ) and chloride (Cl -) ions. Chloride can contaminate receiving water bodies and groundwater supplies through runoff or by infiltrating underlying aquifers (Wegner & Yaggi, 2001). At the University of New Hampshire ...
Conference Paper
In northern climates, runoff from standard pavements has varying seasonal effects on the surrounding environment. Year-round runoff carries transportation associated contaminants into surface waters. During the winter and spring, deicing practices for pavements result in high levels of chloride-laden runoff that is both toxic to aquatic biota and degrades drinking water supplies. The use of pervious pavements for parking lots for new and redevelopment projects are one watershed-based strategy that can both mitigate impacts for new development and reverse impacts in areas with redevelopment. This study presents the findings from 2 pervious pavements, a pervious concrete and a porous asphalt parking lot, studied at the University of New Hampshire Stormwater Center. Winter in particular places great demands on pavements however it was observed that due to the well-drained nature of the reservoir base that freeze thaw was limited. Surface infiltration rates, frost penetration, degree of snow and ice cover, and surface friction were measured on a monthly basis to assess winter performance. Frost penetration was observed to reach depths of eighteen inches however, surface infiltration capacities remained in excess of 200-in/hr. Analysis of snow and ice cover and pavement skid resistance demonstrated that up to 75% less salt was needed for porous asphalt to maintain equivalent or better surface conditions as the reference dense mix asphalt lot. The annual median snow and ice surface cover for the porous asphalt lot was not significantly different than the reference lot with salt applications four times greater (p=0.749 @95% CI). The annual median weighted skid resistance for the porous asphalt lot was 12% greater than the reference lot with greater salt application (p=0.061 @95%CI). Pervious concrete did not demonstrate substantial salt reduction capabilities during storm events; however, `black-ice' formation did not occur during freeze-thaw conditions indicating possible annual reductions. Pavement color and shading were found to be major factors influencing the amount and duration of snow and ice cover on the pervious concrete lot.
... Salt and other chloride-based deicers can have detrimental effects on plants, in particular, roadside vegetation (31,36,37,38,39,40,41,42). Road salt exposure to vegetation from vehicle spray within 10 -20 m (33 -65 ft) of the road has been shown to cause greater severity of foliar damage than root uptake through the soil (22,43). ...
Article
Winter road maintenance operations, commonly known as snow/ice control operations, are one of the most critical functions of state, provincial and local transportation agencies in cold regions. These operations aim to provide safety and mobility by timely and effective application of materials and plowing. The most common materials used are salt (sodium chloride, solid and brine), magnesium chloride-based, and calcium chloride-based deicers, agro-based additives and blends, and abrasives. In practice, the specific choice and application method and rate of these materials dependent on temperature, precipitation type, level of service goals, budget, and environmental sustainability. Best practices of material application are designed to apply the right type and amount of materials in the right place at the right time. This review presents the literature review and agency interviews that were conducted to assemble the information about the use of materials, including types of materials, application tactics, application rates, and application equipment.
Article
This paper reviews wet and dry deposition of aerosol sodium measured from 1980 to 1998 at a suburban site at Argonne National Laboratory, about 40 kilometers southwest of downtown Chicago. The deposition samples were obtained with a wet/dry deposition sampler operated as part of the National Atmospheric Deposition Program/National Trends Network (NADP/NTN) 1. Dry deposition data were for eight-week samples and wet deposition data were for weekly samples. Air quality measurements made with dichotomous and high-volume aerosol samplers at five sites 1-4 km southwest of the Argonne site showed that most of the sodium aerosol mass was in particles greater than 10 urn in diameter. Thus one can expect that the simple bucket measurement of dry deposition is a valid sampling approach for the relatively large sodium particles. Dry and wet depositions of the road salt aerosol in the November to April period were about 103 and 14 mg/m 2, respectively. For the May to October period of warm months, dry and wet depositions of sodium were both about 24 mg/m 2. Road deicing salt is the primary source of the increased sodium in the cold months. The daily application rate of road deicing salt is known for the period 1987 to 2002 for 22 individual areas comprising the Chicago area. A linear correlation analysis of dry deposition of sodium versus road salt applied showed that about 75% of the variance of sodium at the suburban Chicago site could be explained with the linear model. Winter total (wet plus dry) deposition of sodium greatly exceeded summer total deposition, and for the winter months dry deposition greatly exceeded wet deposition.
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In this study, the effects of road salting on the quality of forest soils near the road were monitored in the Krkonoše Mountains (Czech Republic). Physical, chemical properties and microbial parameters of soils were determined and the toxic potentials of soil water extracts were evaluated using the bacterial tests (Microtox and Pseudomonas putida growth inhibition test). Increased concentrations of Na+ ions (up to 100 mg/kg) and pH values up to 8 were found closer to the road. Microbial biomass and respiration activity were significantly reduced at the roadside (ANOVA; P < 0.05), and the metabolic quotients showed that the microbial community was apparently under stress. Large stimulation of Pseudomonas putida growth was determined, especially for salinized samples closest to the road. Oppositely, results showed the unsuitability of bacteria toxicity tests in such cases of pollution. Assessment of intrinsic soil microbial communities is more ecologically relevant and shows the effects that cannot be detected by bacterial toxicity tests.
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The aim of this study was to cross-culturally investigate the instructional efficacy of the Common Knowledge Construction Model (CKCM) with college students learning about ‘factors affecting solubility’ focusing on students’ conceptual understanding, attitudes and scientific habits of mind. Even though the CKCM is a decade old, there has been little study of its effectiveness in different cultural contexts, which is unfortunate because having effective studies from different cultural contexts can increase the strength of generalization. In order to add to the cultural context variation in which the CKCM has been studied, the study reported in this paper investigated the effectiveness of a CKCM undergraduate chemistry unit taught in Turkey and the USA for pre-service teachers. The study was quasi-experimental with the CKCM and country as the independent variables; and conceptual understanding, scientific habits of mind and attitudes towards chemistry as the dependent variables. Data were collected using a pre/post-test administration of the Factors Affecting Solubility Test (FAST), the Scientific Habits of Mind (SHOM) survey, and the Chemistry Attitudes and Experiences Scale (CAES). The data were analyzed using an independent samples t-test, paired samples t-test, and ANCOVA. Statistically significant differences were found between contexts, generally favoring the Turkish pre-service teachers. This is an interesting result in that the findings of the study suggest that the CKCM may be more effective in its adapted setting than in its original (American) setting.
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Sodium and chloride in surface water are typically related to urbanization and population density and can have a significant impact on drinking water sources and the subsequent salinity of aquatic ecosystems. While the majority of research has focused on the impact of deicing salts on urban surface waters in colder climates, the effect of urbanization on sodium and chloride concentrations has been found to occur in warmer climates. This study investigated long-term exports of sodium and chloride from watersheds with increasing urbanization in the humid subtropical Dallas-Fort Worth region. We compared exports to characteristics of urbanization: urban land cover, impervious surface area, and calculated contributions from wastewater discharges. Long-term data (1980-2008) were obtained from five USGS gages located in and around the cities. Exports were calculated by regression analysis between concentrations and discharge and normalized for time and the watershed area. Grab samples were collected from June 2009 to May 2010 and sodium and chloride concentrations quantified. Our results show a strong positive relationship between the mean annual sodium and chloride exports from each watershed and the percent urban land cover and impervious surface area. Long-term increases in sodium and chloride fluxes were found for the three watersheds with the highest percentage of urban land cover. The single largest contributor was wastewater effluent that was estimated to contribute approximately half of the total loads in the three urbanized watersheds. Atmospheric deposition and deicing salts accounted for small amounts of the total export for urbanized watersheds. The source of the remaining salt load is still unknown and may be a combination of non-point sources. Estimates of urban salt exports were similar to estimates from northern watersheds affected by deicing salts.
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