Environmental Impact CMA Versus Road Salt
| CMA | Salt (NaCl) | |
Soils |
Biodegradable in soil. No adverse effect on soil compaction and strength. Increases soil permeability | Sodium may accumulate in soil. Breaks down soil structure, increases erosion. Causes soil compaction which decreases permeability. |
Vegetation |
Little or no adverse effect. May stimulate roadside plant growth. Acetate ion is the most abundant organic acid metabolite found in nature. | Osmotic stress and soil compaction harm root systems. Spray causes foilage dehydration damage. Many plant species are salt sensitive. |
Groundwater |
Poor mobility in soil, unlikely to reach groundwater. Ca, Mg increases water hardness. | Mobile Na and Cl ions readily reach groundwater. Increases Na and Cl concentrations in well water along with alkalinity and hardness. |
Surface Water |
Potential for oxygen depletion through biological oxygen demand(BOD) at concentration greater than 100 ppm in closed systems. Decomposes in 5 days at 20°C, 10 days at 10°C, 100 days at 2°C. Will not stimulate algae growth. | Causes density stratification in ponds and lakes which can prevent reoxygenation. Increases runoff of heavy metals and nutrients through increased erosion. |
Aquatic Life |
Less toxic to trout than salt. Minimal effect on trout eggs up to 5 times expected maximum runoff concentration of 1000 ppm. No effect on food chain (zooplankton, daphnia, bluegill, and fathead minnows) up to up to 1000 ppm. | Monovalent Na, Cl ions stress osmotic balance. Toxic levels: Na 500 ppm stickleback, Cl 400 ppm trout. |
Human/ Mammalian |
Mild skin and eye irritant. Vinegar odor. Acute oral LD50 in rats >5000 mg/kg. Essentially nontoxic. | Sodium linked to heart disease, hypertension. Cl causes unpleasant taste in drinking water. Mild skin and eye irritant. Acute Oral LD50 in rats = 3000 mg/kg. Slightly toxic. Contributes to winter road kills of wildlife. |
Water Treatment Plants |
No significant increase in BOD or impact on bacterial activity. | No significant impact at expected concentrations. |
Air Pollution |
Can reduce sand use and resulting particulate emissions. | Can reduce sand use and resulting particulate emissions. |
