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Amy L. Rhodes
Bachelor of Arts
Environmental Science and Policy
Smith College, Paradise Pond, Water Pollution, Biogeochemistry, Deicing Practice
Deicing agents, especially sodium chloride salt, are widely used in northern climates to prevent roads and walkways from icing in the winter. However, the salt residue persists and accumulates in watersheds, and pollutes surrounding ecosystems. Smith is a microcosm community within Northampton that has a stormwater and landscape management plan that serves the College and is also adjacent to an important waterbody: the Mill River. Therefore, studying the deicing practices and stormwater infrastructure on campus can provide insight to the broader problem of road salt pollution.
In this study, I collected water samples from the Mill River, Lyman Pond, campus storm drains, and pipes that discharge into Paradise Pond, and analyzed these waters for their major ion chemistry and stable isotopic composition. I also analyzed the chemistry of each kind of deicing agent that Smith College uses and interviewed Physical Plant decision makers to document the stormwater designs and deicing practices applied to Smith’s roads and walkways. Water chemistry results revealed that pipes discharge storm runoff with high chloride concentration, up to 443 mg/L, to the Mill River all year round. One pipe receiving runoff from Elm Street/ Route 9, which is maintained by Northampton city, contributes the most salt pollutants to the Mill River, and its chloride concentration has never been lower than the standard of chloride concentration in drinking water from EPA (250mg/L). Chloride concentration in storm drains varies from 2mg/L to 554 mg/L, which may result from dense, salty water that accumulates in the sediment of storm drains due to high density. Of the three deicing agents used by Smith, sodium chloride from rock salt-sand mixture accounts for approximately 92-93% of the deicing pollution discharging to Paradise Pond, with magnesium chloride making up 4-8% of the balance. Smith’s additional deicing agents, Dead Sea Mag pellets and a liquid pretreatment, contribute magnesium chloride to a lesser extent, and their use decreases the need for rock salt application overall. Together, the chemical mixture of the different deicing agents reveals distinctive sodium-to-magnesium ratios in stormwater that vary spatially around campus and could be used as a tracer to distinguish relative salt inputs from campus versus the city. Indeed, while Smith College is discharging high salt concentration runoff to the Mill River, some suggestions are provided to reduce potential salt pollution.
©2023 Wenxi Li. Access limited to the Smith College community and other researchers while on campus. Smith College community members also may access from off-campus using a Smith College log-in. Other off-campus researchers may request a copy through Interlibrary Loan for personal use.
Li, Wenxi, "Connections between Deicing Practices and Infrastructure on Water Chemistry of Lyman and Paradise Ponds at Smith College, Northampton, MA" (2022). Honors Project, Smith College, Northampton, MA.
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