ice gaps may form toxic conveyor belt

Gaps forming in seasonal Arctic sea ice may be creating a toxic conveyor belt, drawing mercury from higher altitudes to rain down on the ice, snow and tundra, a new study said.

The gaps, which come as the region shifts from perennial ice to thinner seasonal ice because of climate change, drive convection currents in the lower atmosphere that cycle mercury and ozone from higher levels toward Earth's surface, where oxidation converts the mercury into a more toxic form, according to the study published online Wednesday in the journal Nature.

"Most atmospheric mercury is in elemental form, but it can be converted to an oxidized form, and this oxidized form is much more reactive, and this will deposit out of the atmosphere very quickly," said atmospheric scientist Christopher W. Moore of the Desert Research Institute in Reno, lead author of the paper.

"We think that these [events] add hundreds of tons of additional deposition of mercury to Arctic ecosystems each year," said fellow author Daniel Obrist, of the institute.

The Arctic ecosystem is home to such animal as seals, commercially harvested fish, and the endangered polar bear, which are being increasingly stressed by climate change.

Primates burn less energy than peers

You may think you're working hard. But relative to other mammals, you're kind of a slacker.

Primates, including humans, expend about half the energy in daily activities compared to similar-size mammals, said a study in the Proceedings of the National Academy of Sciences. The study sheds new light on the question of why primates grow, reproduce and age so slowly.

"It presents a neat alternative hypothesis to our understanding of why primates have such extended life histories," said Steve Ross, an author of the study and director of Lincoln Park Zoo's Lester E. Fisher Center for the Study and Conservation of Apes.

"When we started getting the data in, we were just totally blown away by how different the primates were from anybody else," said lead author Herman Pontzer, associate professor of anthropology at Hunter College.

Primates of different sizes — including ring-tailed lemurs, bonobos, diademed sifaka and common marmosets — were included in the study, and the lower energy expenditure was found across the range of the group. The dozens of non-primate mammals studied included the pygmy gerbil, the gray wolf and the Arabian oryx.

The new data suggest that slow metabolic rates also play a key role in our slow maturation and long life spans. "People are very interested in what makes us age," Pontzer said. "Now that we have a nice connection here to total metabolic rate, that gives us some idea of where to look next."

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