Conclusions

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Results supported our hypothesis that chloride levels in the retention pond will greatly increase due to the use of road salt.

The three sample areas show similar patterns of a change of chloride levels: an increase then a decrease (FIGURE 1).

Levels at site 3 were higher compared to site 1 and 2, possibly due to the higher road salt use in areas that drain to this part of the pond.

The observed patterns of chloride levels are probably explained by the record amounts of snow, below freezing temperatures, and warm days with snow and ice melting.

In a similar study conducted last year, the highest recorded chloride level in the Edgewood Retention Pond was 465 mg/L. Our highest record was 7000 mg/L. Our study differed in that we tested three sites in the pond whereas this group took samples from the same spot. When comparing results, the first noticeable increase in chloride levels was observed in the month of December. Both studies also had a large increase in chloride levels during the months of January and February.

Because of the large amount of snow, more road salt was applied. However, the overuse of salt can negatively impact the environment. The following are examples of impacts:
    Vegetation
    Inhibition of seed germination and root growth for grasses and wildflowers.
    Competition to native species from salt-tolerant invasive species.
    Wildlife:
    Compromised health in birds ingesting salt at 266 mg/kg; median lethal dose in
    birds and mammals in 3,000 mg/kg.
    Aquatic life:
    Decreased dissolved oxygen and increased nutrient loading, promoting
    eutrophication.
    Reduction of number and diversity of maconinvertebrates.
    Median lethal dose (7 days exposure to salt) for 17 species of fish, amphibians,
   crustaceans ranges from 1,440-6,031 mg/L (mean value of 3,345 mg/L) (2006).