-My Research Project
My REU research project for the Summer of 2007 was measuring the daily variations of dissolved gaseous mercury (DGM) in the Raquette River and comparing this data to solar radiation measurements. The purpose of the project was develop a correlation between solar radiation and DGM variations. This was my first research experience, and I have learned a lot about the research process. I enjoyed developing and carrying out experiments, as well as analyzing the data. The executive summary is given below.
The Effects of Solar Radiation on Dissolved Gaseous Mercury Variations in the Raquette River.
Lauren Gorgol , Dustin Nuhfer , Hyun-Deok Choi , Dr. Thomas Holsen
The contamination of water bodies with high mercury levels is a growing concern in many parts of the United States. Large amounts of mercury are emitted into the atmosphere through fossil fuel burning and are deposited back to land and surface waters in many different pathways and locations as part of the mercury cycle. Once mercury reaches a water body it can be transformed to methylmercury by microorganisms. Methylmercury is taken up by biota and stored in the fats of small fish feeding on the biota. Bioaccumulation up the food chain results in hazardous methylmercury levels in predatory fish. This affects fish populations and raises public health concerns for human consumption of these fish (Amyot et al, 2004).
An important component in the mercury cycle is dissolved gaseous mercury (DGM). DGM consists of elemental mercury Hg 0, which is non-water soluble and non-reactive and thus easily volatilizes from a water body to the atmosphere. Research has shown that the rate of DGM volatilization is directly related to solar radiation, in which DGM production peaks at mid-day and reaches a low before sunrise the following day. This diurnal cycle is due to the photo-reduction of water soluble reactive mercury (Hg 2+ ) to non-water soluble Hg 0. Hg 2+ enters a water body through precipitation, and is then converted to volatile Hg 0 by this process. Understanding DGM production is an important part of the mercury cycle as it is the only way that mercury can volatilize from a body of water (O’Driscoll, 2003).
The aim of this research project was to develop techniques to measure DGM and then use these techniques to study the relationship between solar radiation and DGM production in the Raquette River. Solar radiation was measured every five minutes with a Davis Vantage Pro 2 weather station outside of the Rowley Laboratory Building at Clarkson University. DGM was measured using a specially designed gas stripping reactor connected to a Tekran 2537A Mercury Vapour Analyzer. The experimental set-up and reactor is shown in Figures 1 and 2. Samples were taken every 2 hours at the riverside with a 2L glass bottle and then taken back to the laboratory for analysis. The time of sampling ranged from approximately 6am until 12am the following day.
Figure 1:Experimental Set-up
Figure 2: Reactor
Figure 3 shows the relationship between solar radiation and DGM concentration in the Raquette River for the combined days of July 10, 12, and 18. Solar radiation values were time shifted by 90 minutes in advance of sampling and averaged over one hour to obtain the best correlation. Time shifting analysis has been performed in prior research of DGM and solar radiation correlation with greatly improved results (O’Driscoll, 2003). The graph shows a strong positive relationship when fitting a linear trendline to the data with an R squared value of 0.895. The high R squared value obtained suggests that DGM concentration can be approximated by solar radiation data with the equation y = 0.0365x + 22.7.
Further research to contribute to understanding DGM variations due to solar radiation in the Adirondack region would include measuring DGM levels in the nearby Grasse and St. Lawrence Rivers. Another possibility area of research is to measure DGM variations throughout the year to analyze DGM under a wider range of solar radiation.
Amyot, M., Southworth, G., Lindberg, S.E., Hintelmann, H., Lalonde, J.D., Ogrinc, N., Poulain,
A.J., Sandilands, K.A. Formation and evasion of dissolved gaseous mercury in large
enclosures amended with 200HgCl 2. Atmospheric Environment. 2004, 38, 4279-4289.
O’Driscoll, N.J., Lean, D.R.S., Loseto, L., Carignan, R., Siciliano, S.D., The effect of dissolved
organic carbon on the photoproduction of dissolved gaseous mercury in lakes and the
potential impacts of forestry. Environmental Science and Technology. 2004, 38, 2664-
Some of my interests are ultimate frisbee, hiking, and playing flute.
I am on the Snowbabies ultimate frisbee team at the University at Buffalo. We travel to tournaments on the weekends and play all through the year.
I have hiked some of the Adirondack Peaks this summer and last winter. Here's some of the pictures.