Ansgar Walk, Wikimedia Commons // CC BY 2.5
Ansgar Walk, Wikimedia Commons // CC BY 2.5

Polar Bears Are Consuming Less Mercury—But There's a Downside

Ansgar Walk, Wikimedia Commons // CC BY 2.5
Ansgar Walk, Wikimedia Commons // CC BY 2.5

Scientists studying mercury levels in polar bears say that melting sea ice has forced the bears to change their diets. The researchers published their study in the journal Environmental Science & Technology.

Mercury is all around us. Some of it occurs naturally in plants, animals, and the soil. Some of it is our fault, the result of industrial pollution from coal and other fuels.

Regardless of its source, it piles up in living things the same way. Tiny animals eat plants containing mercury, and the mercury stays in their bodies even after all the plant matter is gone. Then those tiny animals are eaten by small animals, and on and on, onward up the food chain. Apex predators like swordfish and sharks are swimming globs of mercury, which is why we tell pregnant women not to eat them.

For the same reason, they shouldn’t eat polar bears, either (although we would kind of like to see them try). Previous tests on bears in the southern Beaufort Sea found alarmingly high mercury levels in the animals’ hair and body tissue—the result of the bears’ diet of mercury-saturated ringed seals. Or their former diet, we should say.

Researchers followed Beaufort Sea bears from 2004 to 2011, taking regular tissue and hair samples from sedated bears and by long-distance biopsy dart. Chemical analysis of the samples showed a clear and steady decline in mercury levels. Each year, the bears’ bodies contained 13 percent less mercury.

But it’s not as though these bears were getting 13 percent smaller. They weren’t wasting away. So what had happened?

It turns out their main prey, ringed seals, had grown scarce. Ringed seals spend most of their time on sea ice. But as the sea ice disappeared, so did they. In response, the bears shifted their predatory attention to bearded seals and bowhead whales, both of which carry less mercury. Even as their mercury levels dropped, the bears' BMI increased, perhaps because they were eating more blubber from the larger prey.

The authors note that the bears in their study might not represent all bears in that region. They could only take samples from the bears they could find along the coast. Less successful hunters might still have been struggling out at sea.

They also say that the polar bears’ prey-switching is, sadly, not a sustainable solution. We’re not exactly experiencing a surplus of whales, here.

nextArticle.image_alt|e
iStock
An Eco-Friendly Startup Is Converting Banana Peels Into Fabric for Clothes
iStock
iStock

A new startup has found a unique way to tackle pollution while simultaneously supporting sustainable fashion. Circular Systems, a “clean-tech new materials company,” is transforming banana byproducts, pineapple leaves, sugarcane bark, and flax and hemp stalk into natural fabrics, according to Fast Company.

These five crops alone meet more than twice the global demand for fibers, and the conversion process provides farmers with an additional revenue stream, according to the company’s website. Fashion brands like H&M and Levi’s are already in talks with Circular Systems to incorporate some of these sustainable fibers into their clothes.

Additionally, Circular Systems recycles used clothing to make new fibers, and another technology called Orbital spins those textile scraps and crop byproducts together to create a durable type of yarn.

People eat about 100 billion bananas per year globally, resulting in 270 million tons of discarded peels. (Americans alone consume 3.2 billion pounds of bananas annually.) Although peels are biodegradable, they emit methane—a greenhouse gas—during decomposition. Crop burning, on the other hand, is even worse because it causes significant air pollution.

As Fast Company points out, using leaves and bark to create clothing may seem pretty groundbreaking, but 97 percent of the fibers used in clothes in 1960 were natural. Today, that figure is only 35 percent.

However, Circular Systems has joined a growing number of fashion brands and textile companies that are seeking out sustainable alternatives. Gucci has started incorporating a biodegradable material into some of its sunglasses, Bolt Threads invented a material made from mushroom filaments, and pineapple “leather” has been around for a couple of years now.

[h/t Fast Company]

nextArticle.image_alt|e
iStock
Undersea Internet Cables Could Be Key to the Future of Earthquake Detection
iStock
iStock

Considering that 70 percent of the planet is covered by oceans, we don't have all that many underwater earthquake sensors. Though there's plenty of seismic activity that happens out in the middle of the ocean, most detection equipment is located on land, with the exception of a few offshore sensor projects in Japan, the U.S., and Canada.

To get better earthquake data for tremors and quakes that happen far from existing sensors, a group of scientists in the UK, Italy, and Malta suggest turning to the internet. As Science News reports, the fiber-optic cables already laid down to carry communication between continents could be repurposed as seismic sensors with the help of lasers.

The new study, detailed in a recent issue of Science, proposes beaming a laser into one end of the optical fiber, then measuring how that light changes. When the cable is disturbed by seismic shaking, the light will change.

This method, which the researchers tested during earthquakes in Italy, New Zealand, Japan, and Mexico, would allow scientists to use data from multiple undersea cables to both detect and measure earthquake activity, including pinpointing the epicenter and estimating the magnitude. They were able to sense quakes in New Zealand and Japan from a land-based fiber-optic cable in England, and measure an earthquake in the Malta Sea from an undersea cable running between Malta and Sicily that was located more than 50 miles away from the epicenter.

A map of the world's undersea cable connections with a diagram of how lasers can measure their movement
Marra et al., Science (2018)

Seismic sensors installed on the sea floor are expensive, but they can save lives: During the deadly Japanese earthquake in 2011, the country's extensive early-warning system, including underwater sensors, was able to alert people in Tokyo of the quake 90 seconds before the shaking started.

Using existing cable links that run across the ocean floor would allow scientists to collect data on earthquakes that start in the middle of the ocean that are too weak to register on land-based seismic sensors. The fact that hundreds of thousands of miles of these cables already crisscross the globe makes this method far, far cheaper to implement than installing brand-new seismic sensors at the bottom of the ocean, giving scientists potential access to data on earthquake activity throughout the world, rather than only from the select places that already have offshore sensors installed.

The researchers haven't yet studied how the laser method works on the long fiber-optic cables that run between continents, so it's not ready for the big leagues yet. But eventually, it could help bolster tsunami detection, monitor earthquakes in remote areas like the Arctic, and more.

[h/t Science News]

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios