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Human Noise Reaches to the Deepest Part of the Ocean

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If a ship passes over the deepest part of the ocean but there’s nobody there to hear it, does it still make a sound? It sure does. New audio recordings from the Mariana Trench, the deepest part of the world's oceans, have captured the sounds of whales, distant earthquakes, storms, and even ships passing tens of thousands of feet above.

Challenger Deep is a valley inside the trench, seven miles below the surface of the ocean. To give you some idea of just how deep that is: If you chiseled Mount Everest off its foundation and dropped it into the Challenger Deep, the mountain’s peak would still be a mile underwater.

Image credit: Center for Coastal and Ocean Mapping - Joint Hydrographic Center

The valley is of great scientific interest, but its distance from the surface and the tremendous amounts of pressure down there have made it hard to study. A team of engineers created a special titanium-coated hydrophone, or underwater microphone, but even they weren’t sure it would work.

"We had never put a hydrophone deeper than a mile or so below the surface, so putting an instrument down some seven miles into the ocean was daunting," engineer Haru Matsumoto said in a press release. "We had to drop the hydrophone mooring down through the water column at no more than about five meters per second. Structures don't like rapid change, and we were afraid we would crack the ceramic housing outside the hydrophone." 

Researchers dropped the hydrophone over the side of a ship. More than six hours passed before the equipment reached the valley floor, but once it did, it began recording. When the research team collected the hydrophone, they brought up 23 days' worth of noise from the bottom.

"You would think that the deepest part of the ocean would be one of the quietest places on Earth," chief project scientist Robert Dziak said in the press release. "Yet there really is almost constant noise from both natural and man-made sources. The ambient sound field at Challenger Deep is dominated by the sound of earthquakes, both near and far was well as the distinct moans of baleen whales and the overwhelming clamor of a category 4 typhoon that just happened to pass overhead. There was also a lot of noise from ship traffic, identifiable by the clear sound pattern the ship propellers make when they pass by."

Curious what those “distinct moans” and that “overwhelming clamor” sound like? Listen for yourself:

The Challenger Deep soundtrack is impressive on its own, as both scientific data and a demonstration of human ingenuity. But it’s also an indicator that our effects on the environment reach farther than we could have imagined. Scientists now know that anthropogenic (human-created) sound wreaks havoc on marine ecosystems, from the largest whales to the smallest fish eggs on coral reefs. From city streets to the Challenger Deep, our noise is more than just noise.

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Switzerland Flushes $1.8 Million in Gold Down the Sewer Every Year
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Switzerland has some pretty valuable sewer systems. As Bloomberg reports, scientists have discovered around $1.8 million worth of gold in the country's wastewater, along with $1.7 million worth of silver.

Scientists at the Swiss Federal Institute of Aquatic Science and Technology examined sewage sludge and effluents, or discharged liquid waste, from 64 water treatment plants and major Swiss rivers. They did this to assess the concentrations of various trace elements, which are "increasingly widely used in the high-tech and medical sectors," the scientists explained in a press statement. "While the ultimate fate of the various elements has been little studied to date, a large proportion is known to enter wastewater."

The study, which was recently published online in the journal Environmental Science & Technology, revealed that around 94 pounds of gold makes its way through Switzerland's sewage system each year, along with 6600 pounds of silver and high concentrations of rare metals like gadolinium and niobium. For the most part, these metals don't harm the environment, researchers say.

With gold and silver quite literally flowing through their sewers, is there any way that Switzerland could turn their wastewater into wealth? Scientists are skeptical: "The recovery of metals from wastewater or sludge is scarcely worthwhile at present, either financially or in terms of the amounts which could be extracted," the release explains.

However, in the southern canton of Ticino, which is home to several gold refineries, the "concentrations of gold in sewage sludge are sufficiently high for recovery to be potentially worthwhile," they conclude.

Switzerland is famous for its chocolate, watches, and mountains, but it's also home to major gold refineries. On average, around 70 percent of the world's gold passes through Switzerland every year—and judging from the looks of it, much of it goes down the drain. As for the sewer silver, it's a byproduct of the chemical and pharmaceutical industry, which is a cornerstone of Switzerland's economy.

[h/t Bloomberg]

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Grass-Fed Beef Is Actually Worse for the Planet, Report Finds
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There are plenty of reasons to reject factory farming, but in the case of beef, your carbon footprint shouldn’t be one of them. According to EcoWatch, new research shows that grazed cattle provide an outsized contribution to greenhouse gasses, as opposed to cattle kept largely indoors and fed on grain.

The report [PDF], released by Oxford’s Food Climate Research Network, aims to provide definitive answers to what has been a heavily debated topic in environmental circles. Some research has found that grazing cattle actually reduces the carbon footprints of beef operations, because all that pasture stores carbon and prevents it from being released into the atmosphere, and because all that chomping stimulates new vegetation growth. Other research has found that the benefits aren’t as great as the grass-fed boosters estimate—especially since the fields of grain used to grow cattle feed for factory farms sequester carbon, too.

The new Oxford research comes down firmly on the side of the latter camp. It finds that while grass-fed operations can help sequester carbon, it’s “only under very specific conditions,” in part since the definition of what a grassland is can vary wildly. There are natural ranges dominated by wild vegetation, there are pastures that are actively maintained and managed by farmers, and there is land that lies somewhere in between. Overgrazing, trampling, and soil conditions can all negatively impact how much carbon the grasses can sequester. And even under the best conditions, the gains can be short-lived. “This sequestering of carbon is even then small, time-limited, reversible, and substantially outweighed by the greenhouse gas emissions these grazing animals generate,” according to FCRN.

And it seems that even if the vegetation does sequester carbon, grass-fed beef is still an outsized source of greenhouse gasses.

To begin with, all cattle are a huge drain on the environment, no matter how you feed them. The report estimates that the livestock supply chain generates around 14.5 percent of global greenhouse gas emissions, and cattle create 65 percent of those livestock emissions. But even compared to cattle in general, grass-fed animals are heavy polluters. Within the global protein supply, grass-fed beef makes up around 1 gram of protein per person, per day, compared to 13 grams from all ruminants (cattle, sheep, goats, etc.). But these grazed cattle generate up to a third of all global greenhouse emissions from ruminants. In other words, grass-eating cattle create an outsized cost—emissions-wise—compared to the meat they provide.

And the carbon sequestration doesn't help enough to offset that. The report estimates that the carbon sequestration that might occur from grazing practices would only offset emissions by 20 percent.

There are other reasons to buy grass-fed beef, of course, whether it’s about ethical concerns with factory farming or just a taste preference. But if you’re going to choose grass-fed, your reason shouldn’t be concern for the environment.

[h/t EcoWatch]

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