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      A transatlantic flight may turn Saharan dust into a key ocean nutrient

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      As dust from the Sahara blows thousands of kilometers across the Atlantic Ocean, it becomes progressively more nutritious for marine microbes, a new study suggests.

      Chemical reactions in the atmosphere chew on iron minerals in the dust, making them more water soluble and creating a crucial nutrient source for the iron-starved seas, researchers report September 20 in Frontiers in Marine Science.

      Dust clouds settling on the Atlantic can spawn phytoplankton blooms that support marine ecosystems, says Timothy Lyons, a biogeochemist at the University of California, Riverside. “Iron is incredibly important for life,” he says. Phytoplankton require it to convert carbon dioxide into sugars during photosynthesis. More

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      Some tadpoles don’t poop for weeks. That keeps their pools clean

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      Some tadpoles don’t poop for the first weeks of their lives. At least, that’s the case for Eiffinger’s tree frogs (Kurixalus eiffingeri), scientists report September 22 in Ecology.

      Eiffinger’s tree frogs are tiny frogs that live in Taiwan and on two Japanese islands: Ishigaki and Iriomote. The tree-dwelling amphibians lay their eggs in puny puddles, which are often nestled in plant stems, tree hollows and bamboo stumps.

      Once the tadpoles hatch, they spend their early lives in these puddles. However, in pools as small as these, there’s not a lot of water to dilute ammonia — a toxic chemical animals release when they pee or poop.

      Bun Ito and Yasukazu Okada, biologists from Nagoya University in Japan, now have uncovered the tadpoles’ secret sanitation strategy — self-induced constipation. The tadpoles store their poop in an intestinal pouch until they start to metamorphize into full-fledged frogs.

      The tadpoles of Eiffinger’s tree frogs (Kurixalus eiffingeri) spend their first few weeks of life in tiny puddles of water nestled within tree hollows and bamboo stumps.Bun Ito

      Ito and Okada raised tadpoles from four different frog species in makeshift nurseries. Once the experiment began, they moved the tadpoles to smaller cribs, plastic cases with a little more than a tablespoon of water. The team measured and compared how much ammonia each species released. They also measured the amount of ammonia each species stored in their guts.

      Eiffinger’s tree frog tadpoles released less than half as much ammonia on average than the species that released the most. And compared with two of the other species, the tadpoles kept more ammonia in their guts. The researchers note that unlike Eiffinger’s tree frogs, the other species typically lay their eggs in open ponds where ammonia is easily diluted. More

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      A hurricane’s aftermath may spur up to 11,000 deaths

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      Meghan Rosen is a staff writer who reports on the life sciences for Science News. She earned a Ph.D. in biochemistry and molecular biology with an emphasis in biotechnology from the University of California, Davis, and later graduated from the science communication program at UC Santa Cruz. More

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      Why Hurricane Helene was so devastating

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      A perfect storm of climate, geologic and geographic conditions have combined to make Hurricane Helene one of the most devastating storms to ever hit the United States. Days after it slammed into Florida’s Big Bend region on September 26 and traveled hundreds of kilometers inland, Helene’s destructive impact has continued to grow.

      Fueled by warm water in the Gulf of Mexico, which climate change made hundreds of times more likely, the tempest rapidly intensified offshore. By the time Helene came onshore as a Category 4 storm, its wind speeds surpassed 209 kilometers per hour (130 miles per hour) (SN: 9/27/24). More

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      A thousands-year-old log demonstrates how burying wood can fight climate change

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      In 2013, Ning Zeng came across a very old, and ultimately very important, log.

      He and his colleagues were digging a trench in the Canadian province of Quebec, one that they planned to fill with 35 metric tons of wood, cover with clay soil, and let sit for nine years. The team hoped to show that the wood wouldn’t decompose, a proof-of-concept that burying biomass could be a cheap way to store climate-warming carbon. But during excavation, they unearthed a pristine, twisted log that was very old, older than anything they could have possibly produced in their experiment. More

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      A vital ocean current is stable, for now

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      The ocean’s circulatory system may not be doing as poorly as previously thought.

      A vital ocean artery known as the Florida Current, a bellwether for the ocean’s ability to regulate Earth’s climate, has seemingly been weakening for decades. But that recent decline might not be quite as severe as suspected. The current has actually remained stable over recent decades, researchers report September 5 in Nature Communications.

      A previously reported decline in the flow had prompted speculations that a major system of ocean currents — known for regulating Earth’s climate — may have weakened recently due to human-caused climate change. Some researchers have suggested that the larger system, known as the Atlantic Meridional Overturning Circulation, or AMOC, could collapse sometime this century, dramatically cooling the northern hemisphere and raising the sea level along some Atlantic coastlines by up to 70 centimeters. More

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      A biogeochemist is tracking the movements of toxic mercury pollution

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      One of the world’s richest biodiversity hot spots is Peru’s Madre de Dios, a region of the Amazon nestled at the base of the Andes mountains. When biogeochemist Jacqueline Gerson first traveled there in 2017, she found herself on a boat headed downstream through the forest. As the riverbanks passed by, she observed a scenic shift.

      At first, “it was beautiful, primary old-growth forest, lots of birds, lots of different wildlife,” says Gerson, a Ph.D. student at Duke University at the time. “Then, as I continued downstream … first you see these rocks,” she adds. “As you keep going, you see pile after pile after pile, and then you started to see some deforestation.”

      She was witnessing the signs of artisanal and small-scale gold mining. Unlike large-scale industrial operations with fleets of dump trucks and excavators, workers here use basic tools or their own hands to extract ore. These informal gold-mining efforts are so prolific in Madre de Dios that they support at least half of the region’s economy.

      In Madre de Dios, artisanal and small-scale gold miners tear down lush tracts of Amazonian rainforest to make way for mining operations, leaving behind mounds of sediment and pits that fill with water.Melissa Marchese

      But there is a price to that gain. The small-scale miners mix mercury into riverbank sediments that contain flecks of gold. This produces a gold-mercury amalgam that can easily be separated from the muck and then burned to isolate the gold. But that burning also releases fumes of mercury into the open air.

      For Gerson, now at Cornell University, illuminating how toxic contaminants flow through the environment is a calling. She studies how human activities contribute to these contaminants and alter their paths. More

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      Climate change could double U.S. temperature-linked deaths by mid-century

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      Heat-related deaths in the United States are on the rise. But how bad will it be 20, 30 or 40 years from now? Scientists now have a clue.

      Currently, an estimated 8,000-plus deaths in the United States every year are associated with extreme temperatures, both hot and cold. Within the next few decades, that number could double or even triple, largely due to heat, researchers report September 20 in JAMA Network Open.

      “As the climate warms, the frequency, duration and intensity of heat waves is increasing. Understanding how this will impact our health is crucial,” Sameed Khatana, a cardiologist at the University of Pennsylvania, says. Our bodies are capable of bearing sweltering temperatures, but as temperatures rise, this ability is pushed to its limit (SN: 6/21/24). More