Road salt

The use of salt for snow and ice control began in the early 20th century. In Paris, sodium chloride was applied on a large scale to combat black ice, although the practice soon revealed disadvantages such as corrosion of iron structures and damage to the hooves of draft animals. Despite these drawbacks, the method proved effective in improving road safety and was soon adopted in other cities and countries. The use of salt for deicing roads began in the United States in the late 1930s, when New Hampshire experimented with spreading granular sodium chloride on roads in 1938. By the winter of 1941–1942, New Hampshire formally adopted a statewide salt-spreading policy; about 5,000 tons of salt were applied on U.S. highways that season. Before the adoption of road salt in New Hampshire, road maintenance in winter typically relied on plowing and spreading abrasives (sand, cinders) for traction, with salt only used occasionally (e.g. to slow freezing in stored sand piles). unloading road salt in Portsmouth, New Hampshire In the post-war era, as the U.S. highway networks expanded and the "bare pavement" standard (expectation that roads be cleared quickly) became dominant, salt usage increased greatly. During the 1950s and 1960s U.S. salt consumption doubled roughly every five years, climbing from about 1 million tons in the mid-1950s to nearly 10 million tons less than a decade later. Supply sources developed along with the demand, large underground rock-salt deposits (formed by the evaporation of ancient seas) supplied much of the salt. The Detroit salt mine (first discovered in 1895) became a prominent example as the mines expanded over the 20th century and supported local deicing operations. Detroit itself was among the earliest cities to apply salt to its roads (circa 1940) believed to be due to its proximity to the resource. A parallel development occurred in Europe. In Germany salt spreading became common in the 1960s as motorization increased and road-safety demands grew. Authorities established salt storage facilities and distributed salt manually from trucks before mechanical spreaders were introduced to improve efficiency. The transition from dry to wet-salt application in the early 1970s represented a further advancement, as saturated salt adhered better to road surfaces and was less susceptible to wind displacement. In later decades salt use stabilized (on the order of tens of millions of tons per year in the U.S.), and attention has shifted to optimizing application methods and mitigating collateral impacts. More recently, occasional supply constraints and environmental concerns have spurred experimentation with reduced-salt strategies and alternative de-icers (e.g., saturated salt–organic blends, calcium or magnesium salts). Specifically, the majority of this is all happening in areas east of Columbus and south of Cleveland. Every year, large amounts of brine are put into the injection wells of Ohio and spread on roads for deicing and dust suppressant. According to the Ohio Revised Code, the application of brine on roads is only allowed if a board or legislator of a county adopts a resolution allowing this. In addition to this, brine is allowed to be applied to a road or surface if it is from a well that is not drilled horizontally. Specifically, the bill hit a hold up in the Natural Resources Committee and never became an official law. == Purpose ==

Salt or brine is placed on the road during the winter season in order to help limit the amount of ice on roads by melting it or breaking it up1. It has been believed that spreading brine on dust roads helps just as well as commercial dust suppressors because of the chemical makeup that is similar between the two. Despite this, recent studies have shown the use of brine as a dust suppressant may not even actually control dust. == Spreading ==

Road salt is applied to road surfaces primarily to prevent the formation of ice or to melt existing snow and ice. Application methods and quantities vary depending on weather conditions, road type, traffic volume, and local policies. Deicing and anti-icing Two main strategies are used in winter road maintenance. De-icing involves applying road salt after snow or ice has formed on the roadway. The salt lowers the freezing point of water, allowing ice to melt and preventing refreezing under certain temperature conditions. Anti-icing is a preventive approach in which salt or salt brine is applied to dry or wet pavement before snowfall or freezing rain occurs. This method is intended to inhibit ice from bonding to the road surface and can reduce the total amount of salt required. Anti-icing is generally considered more efficient than de-icing when applied under appropriate weather forecasts. Application methods Road salt can be applied in various forms, mainly as dry rock salt, pre-wetted salt and brine. Dry rock salt consists of solid salt crystals spread directly onto the roadway. It is the most traditional and widely used form of road salt, despite being less effective at lower temperatures and being prone to being blown off of the roadway by traffic. Road salt and brine are generally spread using a winter service vehicle called a salt spreader. Salt spreaders are typically added to trucks, loaders, or in the case of brine, tankers. The salt is stored in the large hopper on the rear of the vehicle, with a wire mesh over the top to prevent foreign objects from entering the spreading mechanism and hence becoming jammed. The salt is generally spread across the roadway by an impeller, attached by a hydraulic drive system to a small onboard engine. However, until the 1970s, it was often spread manually either by workers shoveling salt from trucks or by smaller wheelbarrow-like vehicles, the latter still being used today for personal use. Some older spreading mechanisms still require it to be manually loaded into the impeller from the hopper. == Mechanics ==

Salt for use of melting ice and snow works through a phenomenon called freezing-point depression, the lowering of a substance's freezing point after the addition of solutes. When road salt is added to roads, aside from providing better friction for vehicles on the road, it also dissolves in the water of the ice, resulting in a lower freezing point. As long as the temperature is above this freezing point, this in turn results in the ice melting. Because of this, ordinary rock salt is only effective down to a range of . At colder temperatures, it can have the opposite effect. If milder weather is expected, road salt is sometimes used even in colder conditions. In very cold and dry weather, the road surface becomes rough and the need for de-icing is reduced. But during extreme cold and rain, the roads can become extremely difficult to pass and, in some cases, roads may need to be closed to traffic. == Types of salt ==

Sodium chloride Sodium chloride is by far the most common kind of road salt. This is mainly due to its widespread use and low cost, and thanks to its large industrial infrastructure, it is used in many industrial and consumer applications. While it is common and inexpensive, its effective temperature range usually does not fall below , and under these temperatures, it is often counter-productive. When used in large quantities, it can also disrupt local ecosystems by heightening the salinity of bodies of water and the soil. Further, rock salt's abrasive nature erodes concrete or asphalt if used heavily. Calcium chloride Calcium chloride is less common compared to sodium chloride. While it does cost five times more to make than sodium chloride, it can cover a far larger area and melts ice almost three times quicker. It has recently started rising in popularity since it is not as environmentally damaging as sodium chloride, and also because of its heightened effectiveness at clearing ice. It also causes less damage to concrete surfaces in comparison to its alternatives. Magnesium chloride Magnesium chloride is another less common road salt. It has a very low environmental impact, and is quite effective at clearing ice. However, it has been discovered that magnesium chloride causes far more damage to concrete surfaces compared to the other salts, and its use as a de-icing chemical on paved roads has largely been discontinued. It is still widespread as a highly effective dust clearer and soil stabiliser in warmer weather and on unpaved roads, and is often preferred by gardeners as it causes far less harm to plant life in comparison to other road salts. AquaSalina A type of deicer made from gases and oils from wells that has been raising concerns amongst many in Ohio the past few years is AquaSalina. In the winter of 2018, the amount of this product sprayed on highways exceeded into a six figure value of gallons. The ODNR found that AquaSalina contains more than 300 times as much radium as the amount the federal government has identified as safe drinking water. Radium is a metal that can lead to multiple types of illnesses including bone, liver and breast cancers. == Environmental impact ==

The widespread use of road salt has significant environmental and infrastructural repercussions. While effective and relatively inexpensive, this practice incurs hidden costs because of its corrosive nature, leading to approximately $5 billion in annual repairs across the United States, according to the country's Environmental Protection Agency. Metals common in plumbing infrastructure, such as copper, lead, and iron, are especially vulnerable. When salt or brine present on the roadway is spewed up by traffic, it hits the bodywork of the vehicle resulting in further corrosion. A study regarding the effect of road salt on bodywork corrosion found that the corrosion rate during the winter periods was reduced to less than 10% on uncoated steel plates. The cosmetic corrosion damages decreased by 50% on cars used on unsalted roads compared to cars driven on salted roads. The United States Environmental Protection Agency approximates that road salt use annually costs the government $5 billion in repairs to cars, trucks, bridges, and roads. Environmental damage One of the primary environmental concerns is the contamination of water sources. As road salt works through dissolving in snow and ice, and thereby lowering its melting point, the salt stays dissolved as the snow melt funnels into storm drains. These storm drains then lead into the sewer system, which washes into rivers, lakes and other bodies of water. It is clear that high levels of chloride, an ion present in most common, inorganic road salts, are toxic to fish, amphibians, and macroinvertebrates. These salt levels could result in the extirpation of freshwater species in salinated bodies of water. The increase of salt concentrations in drinking water could also be affected, as the salt not only permeates rivers and lakes, but the ground water as well. Water starts to taste salty when chloride concentrations exceed 250 mg/L. This elevated salt level could also lead to various elecrolyte imbalances, especially hypernatremia, in people who consume the salinated tap water. This in turn can cause symptoms such as, thirst, weakness, nausea, and loss of appetite, and more severely, confusion, muscle twitching, and bleeding in or around the brain. Tests by the Ohio Department of Natural Resources (ODNR) in 2017 found that a large amount of the samples from wells contained levels of radium that are above the legal limit for drinking water. Road salts also contribute to the process of water eutrophication. It is the process by which nutrients such as nitrogen and chloride rapidly accumulate in water. As a result, these nutrients support the overgrowth of organisms such as algae and create algal blooms. The death of these overgrown algae and algal blooms causes a depletion in oxygen in the water when they decompose, which can kill and harm various aquatic life in the waters. Furthermore, these conditions create a positive feedback loop where it the death of algae continue to create conditions that are favorable for algae to grow in, leading to greater and greater damage. The accumulation of salt in roadside soils adversely affects vegetation by increasing soil salinity, which can hinder plant growth and lead to the death of sensitive species. Overall, this will lead to plants becoming very dry and failing to grow to produce vegetation. In Beijing, they found that de-icing salt resulted in the deaths of 11,000 pavement trees, 1.5 million shrubs, and 200,000 square meters of lawn grass. This degradation of plant life not only disrupts local ecosystems but also contributes to soil erosion. Additionally, wildlife attracted to the salt (such as deer and moose) can be endangered, as they may ingest harmful amounts or be drawn to roadways, increasing the likelihood of vehicle collisions. Road side pools have seen to increase the likelihood of vehicle moose collisions by nearly 80%. The term "Salt Belt" refers to regions with heavy road salt usage, predominantly in the northeastern United States. In these areas, the cumulative effects of salt application are more pronounced, leading to higher concentrations of salt in the environment and exacerbating the associated negative impacts. == Activism ==

Individuals and groups including the Ohio Brine Task For Brine and the Ohio Community Rights Network have taken charge in an attempt to end oil and gas brine spreading in the state. Other groups, such as the Buckeye Environmental Network have held events at which they display their fears of the effects brine spreading can have on future generations using individuals with personal experience of being affected and studies done. == Consumption ==

Alternatives to traditional road salt are being explored to mitigate its environmental and infrastructural damage. While magnesium chloride and calcium chloride are considered less harmful to the environment, they are more expensive and may require higher application rates. Other strategies that help reduce salt usage and discharge into waterways include spraying road surfaces with brine in anticipation of snowfall, as well as using salt additives, such as sand to improve traction, dyes to aid in identification of salted areas, and agricultural by-products like beet juice, pickle juice, and molasses. Innovative solutions, such as porous pavements, have also been developed to reduce ice accumulation and minimize the need for de-icing agents. Many organic and alternative de-icers have shown to be just as effective as rock salt. Although certain scientists propose these biodegradable solutions to be more environmentally friendly than road salts, some studies suggest that they may be more detrimental to certain essential aquatic species such as zooplankton. Zooplankton serve as one of the main sources of food for smaller fish, and are essential in making sure that energy transfer from different trophic levels occurs smoothly in the food web. Further investigation and research is still required before these alternatives can be successfully implemented. The following lists contain the most-commonly used de-icing chemicals and their typical chemical formula. Salt • Sodium chloride (NaCl or table salt; the most common de-icing chemical.) • Magnesium chloride (MgCl2, often added to salt to lower its working temperature, causes less damage to plant life.) • Calcium chloride (CaCl2, often added to salt to lower its working temperature, causes less damage to concrete surfaces.) • Potassium chloride (KCl) • Calcium magnesium acetate (CaMg2(CH3COO)6) • Potassium acetate (CH3COOK) • Potassium formate (CHO2K) • Sodium formate (HCOONa) • Calcium formate (Ca(HCOO)2 Organics • Urea (CO(NH2)2), a common fertilizer • Various agricultural by-products, generally used as additives to sodium chloride • Methanol (CH4O), scarcely used on roads • Ethylene glycol (C2H6O2), scarcely used on roads • Propylene glycol (C3H8O2), scarcely used on roads • Glycerol (C3H8O3), scarcely used on roads == See also ==