Tag Archives: trace elements

UGA Skidaway Institute scientists publish two papers on Arctic processes

The Arctic is experiencing the effects of climate change faster than anywhere on the planet, yet it is one of the least understood regions, due largely to the difficulty of making observations and collecting samples there. With the support of National Science Foundation funding, two University of Georgia Skidaway Institute of Oceanography scientists are studying the biogeochemical processes in the Arctic and recently had their research published in two peer-reviewed science journals.

Postdoctoral researcher Christopher Marsay and assistant professor Clifton Buck have been participants in the international GEOTRACES program which aims to improve the understanding of biogeochemical cycles in the ocean, focusing on important trace elements. Trace elements are present in the ocean in very low concentrations, however some of those elements are essential for marine life and can influence the functioning of ocean ecosystems while others are potentially toxic to plants and animals.

Cliff Buck works with deck equipment during a GEOTRACES cruise in the Pacific Ocean.

“The Arctic part of the GEOTRACES program is particularly important because the region is already showing significant changes as a result of climate change and is relatively poorly studied with respect to many trace elements,” Marsay said.

Marsay is the lead author on both papers, which are the result of analysis of samples he collected on a 64-day GEOTRACES cruise from Dutch Harbor, Alaska to the North Pole and back from August through October 2015.

“On this cruise, our research goals were to describe the chemistry of atmospheric deposition to the region,” Buck said. “These data will then be shared with the scientific community to help better understand biogeochemical cycling of trace elements in the Arctic Ocean.”

The first paper, published in the journal Chemical Geology, describes the concentrations of 11 trace elements in atmospheric samples that Marsay collected during the cruise by pumping large volumes of air through filters. The sources of this material could include natural material from land surfaces, smoke and soot from burning vegetation, and emissions from industrial activity.

“We compare the results to other ocean regions and speculate as to the sources of the material reaching the Arctic,” Marsay said. “An important part of the work is that we used the concentration data to estimate how much of these chemicals settle from the atmosphere to the surface of the ocean.”

In addition to Marsay and Buck, co-authors included David Kadko from Florida International University, William Landing and Brent Summers from Florida State University, and Peter Morton from the National High Magnetic Field Laboratory.

The second paper was published in the journal Marine Chemistry. In it, Marsay and his co-authors examine trace elements in Arctic melt ponds. Melt ponds are a widespread feature of the sea ice in the Arctic during the summer months. As snow melts it forms ponds on top of the ice which eventually drain into the surface ocean.

Chris Marsay collecting samples at the North Pole.

“Melt ponds are an important intermediate step in atmospheric deposition to the surface ocean that is unique to the polar regions and not very well studied,” Marsay said. “Ongoing climate change in the Arctic will change this pathway, and we want to know how that may affect distribution and biological availability of trace elements in the surface ocean.”

The paper brought together measurements of several trace elements made by different research groups involved in the GEOTRACES project. It showed that the chemistry in melt ponds is also influenced by material in sea ice and the seawater beneath the ice, which modifies the chemistry of material deposited from the atmosphere before it reaches the surface ocean.

Additional co-authors on the paper included Ana Aguilar-Islas from the University of Alaska Fairbanks, Jessica Fitzsimmons, Laramie Jensen and Nathan Lanning from Texas A&M University, Mariko Hatta from University of Hawai’i at Manoa, Seth John and Ruifeng Zhang from the University of Southern California, David Kadko from Florida International University, William Landing from Florida State University, Peter Morton from the National High Magnetic Field Laboratory, Angelica Pasqualini from Columbia University, Sara Rauschenberg and Benjamin Twining from the Bigelow Laboratory for Ocean Sciences, Robert Sherrell from Rutgers University, and Alan Shiller and Laura Whitmore from the University of Southern Mississippi.

The two papers can be accessed through the UGA Skidaway Institute website at: https://www.skio.uga.edu/research/research-publications/.

UGA Skidaway Institute scientist to spend winter 2020 locked in Arctic ice

Cliff Buck

Spending the Christmas holidays and the better part of January and February on a ship frozen solid in the Arctic ice cap isn’t most people’s idea of a great way to spend the winter. However, University of Georgia Skidaway Institute of Oceanography scientist Cliff Buck is planning to do just that. Buck is part of a major, international research project named Multidisciplinary drifting Observatory for the Study of Arctic Climate or “MOSAiC.” The goal of the project is to sail the German ice breaker Research Vessel Polarstern into the Arctic Ocean until it becomes locked in the ice and leave it there for a year, all the while using it as a headquarters for scientists to study Arctic climate change.

Climate change is occurring at a higher rate in the Arctic than in other regions. That rate of change is not reflected well in climate change models, mostly due to the lack of year-round observations in the Arctic.

“We care about this because the Arctic is turning out to be one of the more sensitive parts of the planet when it comes to climate change,” Buck said. “It’s warming at rates much higher than other parts of the world, and as it warms, many things are happening, such as the reduction in the expanse of sea ice.”

Those changes have implications on the means and rates that materials flow into the region, which, in turn, affect plant and animal life. Buck’s role will be to monitor the atmospheric deposition of trace elements like iron. Trace elements appear in the ocean in minute concentrations — parts per billion or even parts per trillion. However, they play a key role in the growth of phytoplankton — the tiny marine plants that form the very base of the marine food web and produce approximately half the oxygen in our atmosphere. In much of the world’s ocean, it is the presence or scarcity of iron that regulates the growth of phytoplankton.

Buck and his colleagues hope to develop a better understanding of how trace elements make their way from the upper atmosphere to the ice cap. They can arrive either as little particles, floating in the atmosphere and settling like dust, or they can fall as part of a raindrop or snowflake.

“In the Artic, the composition and abundance of aerosols tend to vary seasonally which is the reason it is important to get a series of observations over a long time scale to see how deposition rates of these aerosols change over the course of a year,” Buck said. “We care about that because in areas removed from river input and other continental influences, atmospheric deposition can be the primary source of trace elements like iron for the surface ocean.”

Buck and colleagues from Florida International University and Florida State University will use a technique utilizing a radioactive isotope of beryllium, itself a trace element, to measure the rate of atmospheric deposition. Beryllium-7 is created only in the upper atmosphere by the exposure of nitrogen and oxygen to cosmic rays, and has a half-life of 53 days. By measuring the concentration of beryllium-7 in samples, Buck will be able to estimate the rate beryllium and other trace elements are being deposited on the surface.

R/V Polarstern
Photo credit: Stephanie Arndt/Alfred Wegener Institute

The research team will take turns working on the ship in shifts of two months at a time. As many as 40 to 50 scientists might be on the R/V Polarstern during each shift, collecting samples and making a wide range of observations throughout the year. Buck is tentatively scheduled to be on board from mid-December 2019 through mid-February 2020.

“I really have no one to blame but myself for being assigned a winter shift,” Buck said. “It is very difficult to make these measurements during the winter, so it is very important to us to insure those winter samples are collected properly. When I said that out loud, they said ‘so I guess you want to go in the winter.’”

Although locked in the Arctic ice cap, the R/V Polarstern will not be stationary. The area where the researchers anticipate the ship will be frozen is subject to a surface current called the Transpolar Drift which propels sea ice from the East Siberian Sea to the Fram Strait, off the east coast of Greenland. The R/V Polarstern could drift as much as 1,500 miles during its year locked in the ice cap.

“The Arctic Ocean is a very interesting place with a lot of wind and a lot of physics going on up there,” Buck said. “You may not perceive the movement, but you will be moving.”

Buck’s participation in the MOSAiC project is funded by a four-year, $350,412 grant from the National Science Foundation Arctic System Science Program.