Date of Award

8-2014

Degree Name

Master of Science

Department

Geological and Environmental Sciences

First Advisor

Dr. Carla M. Koretsky

Second Advisor

Dr. Alan Kehew

Third Advisor

Dr. William Sauck

Keywords

Anoxia, redox, mixing, salt, contamination

Access Setting

Masters Thesis-Open Access

Abstract

Several studies indicate that seasonal applications of road deicers can lead to saline runoff entering surface water and groundwater, which can in turn change the chemistry, density, and physical mixing patterns of urban lakes. An investigation at Asylum Lake, an urban lake located near three major roadways, was conducted to determine the degree of road salt contamination in the lake, to determine if salt loading disrupts seasonal mixing patterns, and to determine the extent of redox stratification present due to eutrophic conditions. Samples were collected monthly from the deepest point in Asylum Lake over a 19-month period and analyzed for dissolved oxygen, temperature, pH, conductivity, alkalinity, NH4+, Mn2+, H2S, Fe2+, PO43-, Ca, Mg, Na, K, Cl-, and SO42-. Groundwater samples were collected over a 10-month period from three wells around Asylum Lake and tested for the same parameters as the lake water.

Asylum Lake never underwent spring mixing, apparently due to the influx of salts entering the lake from snowmelt, and a period of fall mixing was never observed during this investigation. Additionally, Asylum Lake is eutrophic, leading to the development of seasonal redox stratification in the lake water column. However, this stratification is disrupted in the fall and winter following partial fall turnover and subsequent ice cover. Groundwater results indicated background chloride levels to be ~1.2 ppm.

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