Comparing Mortality Rates on Aquatic Macroinvertebrate Populations when Subjected to Conventional and Organic Road Salts

Sodium chloride is the most common road deicer used across the nation. The New York State Department of Transportation applies between 680,000 and 860,000 metric tons of sodium chloride to roads each winter (Kelting 2012). Macroinvertebrates are a key component of wetland ecosystem structure and function. This study compared the differences between conventional and organic road salts on the number of macroinvertebrate fatalities. Macroinvertebrates used in this study were damselfly larvae (Zygoptera) and mayfly larvae (Ephemeroptera). Macroinvertebrates were separated into equal parts and placed in containers with water and one of the salt treatments. The treatments included a control, which was no road salt, sodium chloride, calcium chloride, magnesium chloride, calcium magnesium acetate, and beet juice. Containers were checked every 12 hours and tests were terminated after 96 hours. Sodium chloride was found to be the most harmful for both the damselflies and mayflies. The difference between the conventional and organic road salts was found statistically significant with a p-value of ˂ .01. For the damselflies, the differences between conventional and organic road salt fatalities was found statistically significant, with a p-value of 0.016. For the mayflies, the differences between conventional and organic road salts was not found statistically significant, with a p-value of 0.198. It was found through this study that the organic road salts were less harmful to the mortality rates of macroinvertebrates than conventional road salts.