Mercury – the toxic element once common in household thermometers – is in the air we breathe, the ground beneath our feet and the rain that falls from the sky.
For most people, the only time we worry about mercury nowadays is when we eat fish. And for a good reason, says Mark Olson, atmospheric mercury network site liaison for the National Atmospheric Deposition Program (NADP).
“The problem is that methylmercury attaches to an organism’s muscle tissue,” Olson said, explaining that it accumulates, which means the farther up the food chain a fish is, the more mercury it typically contains. “If you’re eating those fish faster than you can get rid of the mercury from your system, your levels go up.”
That’s a problem because high levels of mercury can cause neurological and organ damage, among other medical issues. It does occur naturally in the environment, but human activity – such as burning coal and other fossil fuels – is a major source of mercury emissions, Olson said.
The NADP has been tracking and studying the environmental effects of atmospheric mercury at sites all over the U.S. since 1995. In 2011, Stone Laboratory’s Peach Point Research Laboratory on South Bass Island became one of those sites with the installation of a monitoring station made by Tekran Instruments Corporation and funded by the Ohio Environmental Protection Agency (EPA). Stone Lab is one of only two NADP sites in Ohio; the other is located at the southern end of the state in Athens at Ohio University.
“These long-term data sets will set us on the right path of reducing human exposure to mercury.”
Dr. Justin Chaffin
The Tekran measures mercury in three different phases – gaseous, particulate and oxidized – said Ohio Sea Grant Research Coordinator Dr. Justin Chaffin, who manages the program for Stone Lab. The instrument takes a reading every 5 minutes and transmits the data to the Ohio EPA and NADP.
Since the installation of the Tekran, Stone Lab has added several other types of mercury-monitoring equipment and protocols to the data collection program. Rainwater and snowfall collect in a half-gallon bottle which is sent away each week for mercury analysis. Four to eight times a year, Stone Lab staff deploys a special sampler that collects and concentrates mercury from the air for a monthly period and sends it away for isotope analysis. Leaf litter was collected and analyzed fall of 2017 and is again planned for 2018. And a meteorological tower next to the Research Laboratory tracks wind speed and direction, which pairs with data from the Tekran.
“So we can track the source (of the mercury),” Chaffin explains. “If we’re getting a west wind, maybe it’s coming from Detroit, for example.”
NADP data is used to create maps showing total mercury deposition, so individuals can see how much mercury pollution there is in their area. It’s also used by modelers who incorporate environmental and human variables to predict future mercury levels, and by scientists, who are examining potential links between atmospheric mercury and mercury levels in fish populations, Olson said.
“These long-term data sets will set us on the right path of reducing human exposure to mercury,” Chaffin said. “We want to minimize it for people through the animals we eat and the crops we grow.”
The project will continue for as long as there is funding, said Phil Downey, environmental specialist for the Air Monitoring Section of the Ohio EPA. The current grant lasts through June 2019.