Easy does it with the salt!

The presence of salt in our air, land and water was largely under the control of natural processes until the mid-twentieth century. Then humans began introducing increasing amounts of salt into the environment, creating the anthropogenic salt cycle.

We have reached the point in many places where the amount of salt being introduced has surpassed nature’s capacity to reduce it. Around the 1940s, rock salt began to be used as a method of de-icing roads. The amount of salt applied grew nationwide from 5000 tons to 20 million tons today. Other sources of salt in the environment come from fertilizer, wastewater, water treatment, mining, and salt water intrusion.

Small amounts of salt are necessary to life, but above certain thresholds, it is toxic. Salts can also extract and co-mobilize metals (mercury, lead, copper, zinc, cadmium), nutrients, radionuclides (e.g., radon) and organics, allowing them to flow into our immediate environment.

A variety of salts are used today introducing excess chemicals including chloride, magnesium, and sodium, to name just a few, into the environment. Each of these causes its own set of problems, but they also combine with each other and other chemicals to form chemical cocktails that alter natural processes and pollute ecosystems. They threaten plants and animals, public health, water quality, soil quality, crop yields and infrastructure.

Excess chloride, for example, not only depletes oxygen levels in freshwater bodies harming aquatic plants and animals, it also pulls lead and mercury out of soils into water and corrodes water pipes. It degrades soil quality by reducing soil permeability, as well as increasing soil salinity. It can increase nutrient levels in water resulting in toxic algae blooms. Salts applied on land infiltrate into ground water or form dust. Water from wells becomes salty, affecting health, and eventually becomes undrinkable. Many wells in the Adirondacks were poisoned from high levels of road salt. Salty dust contributes significantly to infrastructure corrosion.

Reducing salts in the environment is an achievable goal. One of the best places to begin is the use of road salt. We do not have effective, environmentally friendly alternatives to salts, but we do not have to use as much as we do. Reducing road salt requires education about the effects of too much salt, the science of salt use on roads, and the best management practices to reduce salt. Several key facts and concepts underlie effective salt reduction practices. Salt only works effectively to melt ice between 15º and 32º Fahrenheit. When pavement is 32º or warmer, salt is unnecessary. When pavement is colder than 15º, salt does not work. Preventing ice from bonding to pavement (anti-icing) is more effective in achieving dry roads and sidewalks than trying to melt it after the fact (de-icing). Relatively small amounts of salt can effectively reduce ice under the right conditions. Putting down more does not improve its effectiveness.

What can you do to reduce salt pollution?

• Ask your town, state and federal officials to institute legislation and policies that restrict salt application, and support low salt best management practices.
• Apply salt sparingly and only under the right conditions. The pavement should be between 15-32° Fahrenheit. Salt grains should be spaced about 3 inches apart. This translates to using a cup to a cup and a half to an area the size of 2 parking spaces or 10 sidewalk squares – about 700 sq feet. Putting down more than that is wasteful and does not promote faster or more complete melting. Put down salt prior to snowfall, or after snow clearing.
• After the storm, sweep up leftover salt to use next time. Saves you money and helps the environment.
• Do not apply salt to gravel roads or driveways. It creates mud, causing ruts and worsening mud season.
• Calcium magnesium acetate (CMA) is less toxic than rock salt (sodium chloride) or calcium chloride, though more expensive.
• Never use fertilizer as a de-icer.
• Make sure your contractor is using low salt practices such as treating pavements. prior to storms, or applying properly sized sand/gravel for gravel surfaces.