. Scientific Frontline

Saturday, January 29, 2022

Modern Day Gold Rush Turns Pristine Rainforests into Heavily Polluted Mercury Sinks

Illegal gold miners use mercury to bind gold particles, then separate the two metals by burning gold-mercury pellets in open fire ovens, releasing clouds of highly toxic mercury particles into the atmosphere.
Credit – Melissa Marchese

If you had to guess which part of the world has the highest levels of atmospheric mercury pollution, you probably wouldn’t pick a patch of pristine Amazonian rainforest. Yet, that’s exactly where they are.

In a new study appearing in the journal Nature Communications, an international team of researchers show that illegal gold mining in the Peruvian Amazon is causing exceptionally high levels of atmospheric mercury pollution in the nearby Los Amigos Biological Station.

One stand of old-growth pristine forest was found to harbor the highest levels of mercury ever recorded, rivaling industrial areas where mercury is mined. Birds from this area have up to twelve times more mercury in their systems than birds from less polluted areas.

The spread of mercury pollution from gold mining has primarily been studied in aquatic systems. In this study, a team of researchers led by Jacqueline Gerson, who completed this research as part of her Ph.D. at Duke, and Emily Bernhardt, professor of Biology, provide the first measurements of terrestrial inputs, storage and impact of atmospheric mercury to forests and measurements of methylmercury, the most toxic form of mercury.

Illegal miners separate gold particles from river sediments using mercury, which binds to gold, forming pellets large enough to be caught in a sieve. Atmospheric mercury is released when these pellets are burned in open fire ovens. The high temperature separates the gold, which melts, from the mercury, which goes up in smoke. This mercury smoke ends up being washed into the soil by rainfall, deposited onto the surface of leaves, or absorbed directly into the leaves’ tissues.

Thawing permafrost can accelerate global warming

Outcrop of Yedoma sediments with the thick ice masses underlain by river sediments exposed on an arm of the Lena River in the river delta.
Credit: Janet Rethemeyer

Thawing permafrost in the Arctic could be emitting greenhouse gases from previously unaccounted-for carbon stocks, fueling global warming. That is the result of a study conducted by a team of geologists led by Professor Dr Janet Rethemeyer at the University of Cologne’s Institute of Geology and Mineralogy, together with colleagues from the University of Hamburg and the Helmholtz Centre Potsdam – GFZ German Research Centre for Geosciences. In the Siberian Arctic, the research team determined the origin of carbon dioxide released from permafrost that is thousands of years old. This research endeavor is part of the German-Russian research endeavor ‘Kopf – Kohlenstoff im Permafrost’, funded by the German Federal Ministry of Education and Research (BMBF). The paper ‘Sources of CO2 Produced in Freshly Thawed Pleistocene-Age Yedoma Permafrost’ has now appeared in Frontiers in Earth Science.

Global climate change is causing temperatures to rise sharply, especially in the Arctic. Among other things, higher temperatures are causing more and more permafrost soils, which have been frozen for thousands of years, to thaw. Particularly affected is so-called ‘yedoma’ permafrost, which is widespread in areas that were not covered by ice sheets during the last ice age. Yedoma contains up to 80 per cent ice and is therefore also called ice complex. The ground ice can thaw very abruptly, causing the bedrock to collapse and erode. Such processes, known as thermokarst, make carbon previously stored in the frozen ground accessible to microorganisms, which break it down and release it as carbon dioxide and methane. The greenhouse gas release amplifies global warming, which is known as permafrost-carbon feedback.

New species of 'incredibly rare' insect discovered

The newly discovered leafhopper Phlogis kibalensis
Credit: Dr Alvin Helden, Anglia Ruskin University 

An Anglia Ruskin University (ARU) scientist has discovered a new species that belongs to a group of insects so rare that its closest relative was last seen in 1969.

Dr Alvin Helden found the new species of leafhopper, which he has named Phlogis kibalensis, during field work with students in the rainforest of the Kibale National Park in western Uganda, and the discovery has been announced in the journal Zootaxa.

The new species, which has a distinctive metallic sheen, pitted body, and, in common with most leafhoppers, uniquely-shaped male reproductive organs – in this case partially leaf-shaped – belongs to a group, or genus, called Phlogis.

Prior to this new discovery, the last recorded sighting of a leafhopper from this rare genus was in Central African Republic in 1969.

Friday, January 28, 2022

A 3D View of an Atmospheric River

Features in Earth’s atmosphere, spawned by the heat of the Sun and the rotation of the Earth, transport water and energy around the globe. Clouds and precipitation shown here are from NASA’s MERRA-2 reanalysis, a retrospective blend of a weather model and conventional and satellite observations.

Video: NASA's Scientific Visualization Studio
Final Editing and Conversion: Scientific Frontline


Invisible machine-readable labels that identify and track objects

Caption:MIT scientists built a user interface that facilitates the integration of common tags (QR codes or ArUco markers used for augmented reality) with the object geometry to make them 3D printable as InfraredTags.
Credits: Photos courtesy of MIT CSAIL.

If you download music online, you can get accompanying information embedded into the digital file that might tell you the name of the song, its genre, the featured artists on a given track, the composer, and the producer. Similarly, if you download a digital photo, you can obtain information that may include the time, date, and location at which the picture was taken. That led Mustafa Doga Dogan to wonder whether engineers could do something similar for physical objects. “That way,” he mused, “we could inform ourselves faster and more reliably while walking around in a store or museum or library.”

The idea, at first, was a bit abstract for Dogan, a 4th-year PhD student in the MIT Department of Electrical Engineering and Computer Science. But his thinking solidified in the latter part of 2020 when he heard about a new smartphone model with a camera that utilizes the infrared (IR) range of the electromagnetic spectrum that the naked eye can’t perceive. IR light, moreover, has a unique ability to see through certain materials that are opaque to visible light. It occurred to Dogan that this feature, in particular, could be useful.

Researchers identify proteins that could predict liver transplant rejection

Northwestern University scientist have discovered families of proteins in the body that could potentially predict which patients may reject a new organ transplant, helping inform decisions about care.

The advancement marks the beginning of a new era for more precise study of proteins in specific cells.

Scientists tend to look at shifting patterns of proteins as if through goggles underwater, taking in just a fraction of available information about their unique structures. But in a new study in the journal Science, scientists took a magnifying glass to these same structures and created a clarified map of protein families. They then held the map up in front of liver transplant recipients and found new indicators in immune cell proteins that changed with rejection. The study is available online and will be published tomorrow (Jan. 28).

The result, the Blood Proteoform Atlas (BPA), outlines more than 56,000 exact protein molecules (called proteoforms) as they appear in 21 different cell types — almost 10 times more of these structures than appeared in similar previous studies.

Climate change in the Early Holocene - archaeology report

New insight into how our early ancestors dealt with major shifts in climate is revealed in research by an international team, led by Professor Rick Schulting from Oxford University’s School of Archaeology.

  • Radiocarbon dating from a prehistoric cemetery in Northern Russia reveals human stress caused by a global cooling event 8,200 years ago.
  • Early hunter gatherers developed more complex social systems and, unusually, a large cemetery when faced by climate change

Published in Nature Ecology & Evolution, the report reveals, new radiocarbon dates show the large Early Holocene cemetery of Yuzhniy Oleniy Ostrov, at Lake Onega, some 500 miles north of Moscow, previously thought to have been in use for many centuries, was, in fact, used for only one to two centuries. Moreover, this seems to be in response to a period of climate stress.

"The team believes the creation of the cemetery reveals a social response to the stresses caused by regional resource depression...[it] would have helped define group membership for what would have been previously dispersed bands of hunter-gatherers - mitigating potential conflict over access to the lake’s resources"

The team believes the creation of the cemetery reveals a social response to the stresses caused by regional resource depression. At a time of climate change, Lake Onega, as the second largest lake in Europe, had its own ecologically resilient microclimate. This would have attracted game, including elk, to its shores while the lake itself would have provided a productive fishery. Because of the fall in temperature, many of the region’s shallower lakes could have been susceptible to the well-known phenomenon of winter fish kills, caused by depleted oxygen levels under the ice.

Thursday, January 27, 2022

Expanded University of Hawaiʻi asteroid tracking system can monitor entire sky

Left: Sutherland ATLAS station during construction in South Africa.
Credit: Willie Koorts (SAAO)
Right: Chilean engineers and astronomers installing the ATLAS telescope at El Sauce Observatory.

A state-of-the-art asteroid alert system operated by the University of Hawaiʻi Institute for Astronomy (IfA) can now scan the entire dark sky every 24 hours for dangerous bodies that could plummet toward Earth.

The NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) has expanded its reach to the southern hemisphere, from two existing northern-hemisphere telescopes on Haleakalā and Maunaloa. Construction is now complete and operations are underway on two additional telescopes in South Africa and Chile.

Telescope unit on Haleakalā, Maui.
Photo credit: Henry Weiland

Large Herbivores Help Rare Species Persist in a Warming Arctic

A herd of caribou in arctic Greenland. Caribou at this study site have been declining over the past several years, while muskoxen have been increasing. Such herbivores help rare plant species persist in a rapidly changing climate.
Credit: Eric Post/UC Davis

Being common is rather unusual. It’s far more common for a species to be rare, spending its existence in small densities throughout its range. How such rare species persist, particularly in an environment undergoing rapid climate change, inspired a 15-year study in arctic Greenland from the University of California, Davis.

Arctic wintergreen, a very rare species,
grows among birch and willow
shrubs near Kangerlussuaq, Greenland.
Credit: Eric Post/UC Davis
The study, published in the journal Scientific Reports, found that caribou and muskoxen helped mitigate the effects of climate change on rare arctic plants, lichens and mushrooms at the study site.

The authors suggest that by constraining the abundance of the two most common plant species — dwarf birch and gray willow — large herbivores may allow other, less common species to persist rather than be shaded or outcompeted for nutrients by the woody shrub’s canopy, or suppressed by leaf litter and cooler soils.

“This is more evidence that conserving large herbivores is really important to maintaining the compositional integrity of species-poor systems like the arctic tundra,” said lead author Eric Post, director of the UC Davis Polar Forum and a professor in the UC Davis Department of Wildlife, Fish and Conservation Biology.

Microbes help hibernating animals recycle nutrients, maintain muscle through winter

Like many hibernators, thirteen-lined ground squirrels retain muscle tone and healthy gut microbiomes through hibernation even though they aren’t eating or moving around. Their success at rest may help humans make long space voyages.
Credit: Rob Streiffer

To get through a long winter without food, hibernating animals — like the 13-lined ground squirrel — can slow their metabolism by as much as 99 percent, but they still need important nutrients like proteins to maintain muscles while they hibernate. A new study from the University of Wisconsin–Madison shows that hibernating ground squirrels get help from microbes in their guts.

The discovery could help people with muscle-wasting disorders and even astronauts on extended space voyages.

“The longer any animal doesn’t exercise, bones and muscles start to atrophy and lose mass and function,” says Hannah Carey, an emeritus professor in the UW–Madison School of Veterinary Medicine and co-author of the new study, published today (Jan. 27) in the journal Science. “Without any dietary protein coming in, hibernators need another way to get what their muscles need.”

One source of nitrogen, a vital building block for amino acids and proteins, accumulates in the bodies of all animals (including humans) as urea, a component of urine. The researchers knew that urea that moved into the squirrels’ digestive tract could be broken down by some gut microbes, which also need nitrogen for their own proteins. But the researchers wanted to see if some of that urea nitrogen freed up by the microbes was also being incorporated into the squirrels’ bodies.

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