Changes of water chemistry in the mixing zone between the Bear River Bay and Great Salt Lake.

We have examined the mixing zone between the predominantly fresh water of Bear River Bay and the saline water of Great Salt Lake during the summer season of 2019. The impetus for this research is a scarcity of data reflecting the seasonal and diel changes of complex water mixing systems separated by a railroad causeway. Monthly measurements of specific conductance in the study area have historically ranged from 1000 to more than 200,000 uS/cm, pH fluctuates between 6.9 and 9.4, elevated concentrations of Mercury range from 3 to 40 ng/L, and levels of nutrient concentrations, such as Nitrogen, have been recorded below 1 mg/L and above 20 mg/L. Similar studies in the wetlands located along the southern coastline of Great Salt Lake indicated significant diel fluctuations in Se and As concentrations. The need to collect additional baseline data is particularly pressing at this time, as the Bear River is being assessed for a dam project that would likely change flow dynamics. Our study utilized a microwave digestor to prepare samples and ICP-MS to analyze samples. The field parameters were measured using a Toll 9500 probe. Initial results confirm a relatively wide range of pH and total dissolved solids, and high concentrations of Mercury, Selenium, and Arsenic. We have also observed a significant gradient in heavy metals between the Bear River Bay and Great Salt Lake and diel fluctuations in pH and heavy metals. The initial phase of our research began in the summer of 2019 and will continue into 2020.