Arctic sea ice 'frost flowers' in bloom at University of Manitoba lab

While others in Winnipeg are lamenting the bone-chilling temperatures and extreme weather warnings, researchers at a unique lab are celebrating the cold and seizing the opportunity to grow tiny, briny, icy structures called frost flowers.

"I think [I'm] one of those people that actually likes a cold spell, so this is perfect," said Feiyue Wang, director of the University of Manitoba's Sea-ice Environmental Research Facility (SERF).

SERF is the only outdoor experimental pool of its kind in Canada, and one of only a handful like it worldwide. At about 18 metres long, nine metres wide, and 2½-metres deep, the outdoor pool gives researchers a chance to simulate polar ocean conditions and grow their own sea ice at a fraction of the cost of studying up north.

Every fall since the project launched in 2012, Wang and others have filled the pool with their own homemade salt-water concoction. They heat the pool into January, and if things are considerably chilly, they unplug the heat and let the winter weather take its course.

Over the next few days, researchers keep a close eye on things like water temperature and chemistry, and ice growth in the pool. The goal is to better understand how sea ice factors in to concerns about climate change and pollution in the Arctic.

"We definitely see the active role of brine as a transport medium for chemical contaminants from the atmosphere to the ocean," Wang said. "But in certain cases, it could be from the ocean to the surface, and eventually it could affect the [ground-level] atmosphere as well."

Lessons learned up north

Wang, his colleagues and a small group of master's and doctoral students also spend time working in the field in the high Arctic. Lessons learned up north informed the construction and design of the pool thousands of kilometres south in Manitoba. Likewise, results gleaned from freezing their own salt water on campus helps them focus their efforts up north.

Whether it's under the semi-controlled environment of SERF, or out in the open on the frozen surface of an Arctic sea, both have their pros and cons from a research standpoint.

"What's often lacking is the controlled experiment. When you're working in the field, things change all of the time," Wang said.

"Sometimes you formulate a hypothesis based on field data. You wish you had the capability to control the rest of the variables."

Being subject to the whims of swirling winds, varying sunlight and unpredictable snow fall out on a desert-like landscape makes it hard to tease apart different factors influencing the sea ice environment.

At SERF, researchers can choose to vary one or two variables at a time, which allows them to do detailed studies of each mechanism involved in the freezing of polar sea ice. From there, they're better equipped to make inferences about how a contaminant and neuro-toxin like mercury finds its way from the atmosphere into oceans.

Salt water, porous ice

In a freshwater ecosystem like Lake Winnipeg, it's imagined that ice locks the lake off from its surrounding environment in the winter, isolating the water from the atmosphere above. Frozen polar oceans are different.

"What's different in the sea ice in the Arctic ocean environment is that sea water is so saline that when the ice forms, that the brine is ejected, so you have this pocket of space with very saline water that depresses the freezing point," Wang said. 

"It makes the sea ice a more porous structure than one piece of solid ice that completely separates the air from the water."

Contamination concerns

At SERF, researchers monitor feedback loops and the role sea ice plays in the broader climate system, and one of the ways they do that is by studying the saline-rich, crystalline frost flowers.

When ice first starts to form on the surface of the Arctic ocean, brine moves up through the icy flowers on the surface of the cooling polar ocean, opening up a pathway for chemical contaminants like mercury. They scale down the salty arms of the flowers like a ladder into the marine ecosystem, Wang said.

"You have a solid sea ice cover, but you also have all these liquid channels that allow energy, chemicals, gasses to still transport through," Wang said.

In the case of mercury, it's thought that once it makes the leap from the air into the ocean, it can be absorbed by microscopic zooplankton, which is then consumed by another diminutive predator. Those predators get consumed by small fish, which are eaten by bigger fish, and so on through the food chain. Eventually, contaminants start showing up in the fat stores of marine mammals like whales, some of which are dietary staples for people in remote northern communities.

Arctic oil spills

This year's experiments at SERF just got started over the weekend. Wang and others will be conducting a few separate, but complementary, studies this winter. 

The first is on the geophysical side. It involves monitoring the surface of the ice and developing a way to study Arctic ice remotely using satellites. They'll look at how carbon dioxide and mercury cycle in and out of polar oceans and interact with the ice, too.

That should wrap up in early February. Once it does, the ice will be melted down and frozen again. Then, they'll introduce crude into the mix to mimic the effects of an Arctic oil spill.

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