Halfman Assesses Nutrient Loading
Posted on Wednesday, August 08, 2012
Since he began working at Hobart and William Smith Colleges in 1994, Professor of Geoscience John Halfman has been monitoring the water quality of the Finger Lakes. In the beginning, Halfman monitored Seneca Lake and the major streams that flow into it. In 2005 his research expanded to include eight of the 11 Finger Lakes.
This summer, Halfman is assisted by several students who are helping him collect, analyze, and record hundreds of water samples each week. The research focuses on monitoring the relative levels of certain contaminates and nutrients in the lakes' and streams' water to determine how the lakes themselves are dealing with the human use of land in their watersheds. Two such nutrients are nitrates and phosphates, which can enter groundwater systems, move into streams and then deposit in the lakes. This artificial introduction of nutrients into the lake system is known as nutrient loading or eutrophication.
Laura Carver-Dionne '13, Carly Ellis '14 and Phillip Hackett ‘14 are a few of the summer research students who recently traveled to Canandaigua Lake with Halfman to study its water.
"I think it's important for people to have information about the fresh water sources they live around," says Ellis. "I am interested in water quality because of the limited availability of freshwater. I would like to work in this field, helping to resolve these problems."
When collecting samples from the Finger Lakes, Halfman and his research group travel to two predetermined locations on each lake. "The locations are picked based on depth, and if they serve as a good average for the lake as a whole," says Halfman. At each location a surface water sample as well as a sample from the bottom of the lake are collected and analyzed.
"Working with Professor Halfman on water quality in the Finger Lakes is great because, not only do I get to spend time in the lab analyzing samples, I get to go out in the field and collect samples," says Carver-Dionne.
Aboard the Colleges' pontoon-research boat, the 25-foot JB Snow, or on the 65-foot, steel hulled research vessel the William Scandling, the samples are analyzed for the amount of oxygen dissolved, alkalinity, pH, temperature, and the conductivity of the water. When the bottom water sample is collected, a device known as a CTD is used to collect the same information in a vertical profile. Water samples are bottled and taken to the geoscience lab on campus where they are analyzed for nutrient content using a technique known as spectroscopy.
Students also use a device called a Secchi disk to measure the depth to which light can penetrate the lake. This gives a good reference for the amount of nutrients present in the lake water.
The outcomes for student researchers are impressive. Many students who work with Halfman during the summer and the academic year present results at national conferences, others perform an Honors Project based on the research, and some write and publish papers with Halfman.