Caribou gut parasites indirectly create a greener tundra
Infected herbivores eat less, allowing plants to flourish

A caribou on Siberia’s Yamal Peninsula browses on some willows. 

JEFF KERBY

By Jake Buehler

Gut parasites in large plant eaters like caribou thrive out of sight and somewhat out of mind. But these tiny tummy tenants can have big impacts on the landscape that their hosts travel through.

Digestive tract parasites in caribou can reduce the amount that their hosts eat, allowing for more plant growth in the tundra where the animals live, researchers report in the May 17 Proceedings of the National Academy of Sciences. The finding reveals that even nonlethal infections can have reverberating effects through ecosystems.

Interactions between species have long been known to ripple through ecosystems, indirectly impacting other parts of the food web. When predators eat herbivores, for example, a reduction in plant-eating mouths leads to changes in the plant community. This is how sea otters, for example, can encourage kelp growth by feeding on herbivorous urchins (SN: 3/29/21).

“Anytime you have a change in species interactions that changes what the animals are doing on the landscape, it can influence their impact on the ecosystem,” says Amanda Koltz, an ecologist at Washington University in St. Louis.

When parasites and pathogens kill their hosts, it can have a similar effect to predators on ecosystems. A prime example is the rinderpest virus, which in the late 19th century devastated populations of ruminants — buffalo, antelope, cattle — in sub-Saharan Africa. Once wildebeest populations in East Africa were spared further infection following the vaccination of cattle and the eradication of the virus, their exploding numbers trimmed the grass back in the Serengeti and led to other landscape changes.

But unlike rinderpest, most infections aren’t lethal. Nonlethal parasite infections are pervasive in ruminants — plant eaters that play key roles in shaping vegetation on land. Koltz and her team wondered if changes to a ruminant’s overall health or behavior from a chronic parasitic infection could also induce changes in the surrounding plant community.

Parasites like this brown stomach worm (Teladorsagia circumcincta), shown in an SEM image, are common residents of the guts of ruminants such as sheep, cattle and deer.

DENNIS KUNKEL MICROSCOPY/SCIENCE SOURCE

The researchers looked to caribou (Rangifer tarandus). Using data from published studies, Koltz and her team developed a series of mathematical simulations to test how caribou survival, reproduction and feeding rate could be influenced by stomach worm (Ostertagia spp.) infections.

The scientists then calculated how these effects could alter the total mass of and population changes in the caribou, parasites and plants. The simulations predict that not only could lethal infections trigger a cascade leading to more plant mass, but also nonlethal infections had just as large an effect. Sickened caribou that ate less or experienced a drop in reproduction rate led to an increase in plant mass when compared with a scenario with no parasites.

The team also analyzed data from 59 studies on 18 species of ruminants and their parasites, gathering information on how the parasites impact host feeding rates and body mass. The analysis found that chronic parasitic infections generally cause many types of herbivores to eat less, also reducing their body mass and fat reserves.

Indirect ecological ramifications from parasitic infections could be common in ruminants all over the world, the researchers conclude.

The study “highlights that there are widespread interactions that we’re not considering in ecosystem contexts quite yet, but we should be,” Koltz says.

Globally, parasites face an uncertain future with fast environmental changes — like climate change and habitat loss from changes in land use — altering relationships with their hosts, potentially leading to many parasite extinctions. “How such changes in host-parasite interactions might disrupt the structure and functioning of ecosystems is a topic that we should be thinking about,” Koltz says.

The findings also are “going to change how we think about what controls ecosystems,” says Oswald Schmitz, a population ecologist at Yale University who was not involved in the research. “Maybe it isn’t predators that are necessarily controlling the ecosystem, maybe the parasites are more important,” he says. “And so, what we really need to do is more research that disentangles [this].”

Scientists are rapidly gaining a better understanding of parasites’ ubiquity and abundance, says Joshua Grinath, an ecologist at Idaho State University in Pocatello. “Now we are challenged with understanding the roles of parasites within ecological communities and ecosystems.”

sciencenews.org

CITATIONS

A.M. Koltz et al. Sublethal effects of parasitism on ruminants can have cascading consequences for ecosystems. Proceedings of the National Academy of Sciences. Vol. 119, May 17, 2022, e2117381119. doi: 10.1073/pnas.2117381119.

R.M. Holdo et al. A disease-mediated trophic cascade in the Serengeti and its implications for ecosystem C. PLOS Biology. Published September 29, 2009. doi: 10.1371/journal.pbio.1000210.

C.J. Carlson et al. Parasite biodiversity faces extinction and redistribution in a changing climate. Science Advances. Vol. 3., September 6, 2017. doi: 10.1126/sciadv.1602422.

About Jake Buehler

KINETOSCOPE

Prehistoric people may have used light from fires to create dynamic art

When brought near flickering flames, stone engravings of animals seem to move

Replicas of stones featuring animal engravings, which were excavated in southern France, are shown positioned around a fire. Researchers think prehistoric people would have placed them this way so flickering flames would create the illusion of moving images.        A. NEEDHAM ET AL/PLOS ONE 2022 (CC-BY 4.0)

By Allison Gasparini

Prehistoric people may have used firelight to create the illusion of movement in their art.

An analysis of 50 engraved stones excavated in France suggests that when the stones were placed near a fire, the flickering light made the engraved animals seem to move, researchers report April 20 in PLOS ONE.

These stones, or “plaquettes,” were found in the 1860s in a rock-shelter called Montastruc, and are engraved with animals such as horses, ibex and deer. The site was used by Magdalenian people, hunter-gatherers who inhabited the area between 23,000 and 14,000 years ago.

The researchers analyzed heat damage on the stones, which was indicative of them being directly exposed to high temperatures for a prolonged period, and created 3-D models of the plaquettes. Those models were imported to a virtual reality software where they were placed next to a virtual hearth so that the areas of heat damage were closest to the flames, mimicking how the stones may have been placed in real life. The researchers then observed the visual effects of the virtual reality light.

It was surprising to see how dynamic the art was and “how changed your experience of the art was by a simple thing, just putting it close to a fire,” says Andy Needham, an archaeologist at the University of York in England. The work suggests that the artists purposely engraved along the contours of the rock to influence viewers to see meaningful movement through the random pattern of firelight, he says.

The finding adds to archaeologists’ understandings of the relationship between early people’s artwork and fire. Another recent study found that Stone Age humans created “hidden” art in dark caves which could be illuminated and made visible only with the help of the right lighting (SN: 7/6/21).

CITATIONS
A. Needham et al. Art by firelight? Using experimental and digital techniques to explore Magdalenian engraved plaquette use at Montastruc (France). PLOS ONE. Published online April 20, 2022. doi: 10.1371/journal.pone.0266146.

sciencenews.org

Ancient penguin bones reveal unprecedented shrinkage in key Antarctic glaciers

Thwaites Glacier is losing ice more quickly than at any other time in the last 5,500 years

Pine Island Glacier in Antarctica, shown in February of 2020 shedding ice into Pine Island Bay, may be retreating at an unprecedented rate.       NASA EARTH OBSERVATORY, USGS

By Douglas Fox

sciencenews.org
JUNE 9, 2022 

Antarctica’s Pine Island and Thwaites glaciers are losing ice more quickly than they have at any time in the last few thousand years, ancient penguin bones and limpet shells suggest.

Scientists are worried that the glaciers, two of Antarctica’s fastest-shrinking ones, are in the process of unstable, runaway retreat. By reconstructing the history of the glaciers using the old bones and shells, researchers wanted to find out whether these glaciers have ever been smaller than they are today.

“If the ice has been smaller in the past, and did readvance, that shows that we’re not necessarily in runaway retreat” right now, says glacial geologist Brenda Hall of the University of Maine in Orono. The new result, described June 9 in Nature Geoscience, “doesn’t give us any comfort,” Hall says. “We can’t refute the hypothesis of a runaway retreat.”

Pine Island and Thwaites glaciers sit in a broad ocean basin shaped like a bowl, deepening toward the middle. This makes the ice vulnerable to warm currents of dense, salty water that hug the ocean floor (SN: 4/9/21). Scientists have speculated that as the glaciers retreat farther inland, they could tip into an irreversible collapse (SN: 12/13/21). That collapse could play out over centuries and raise the sea level by roughly a meter.

Researchers dated ancient shorelines (seen here as the series of small ridges in the rocky terrain between the foreground boulders and background snow) on islands roughly 100 kilometers from Pine Island and Thwaites glaciers in Antarctica to help figure out if the glaciers are in the process of unstable, runaway retreat.      JAMES KIRKHAM

To reconstruct how the glaciers have changed over thousands of years, the researchers turned to old penguin bones and shells, collected by Scott Braddock, a glacial geologist in Hall’s lab, during a research cruise in 2019 on the U.S. icebreaker Nathaniel B. Palmer.

One afternoon, Braddock clambered from a bobbing inflatable boat onto the barren shores of Lindsey 1 — one of a dozen or more rocky islands that sit roughly 100 kilometers from where Pine Island Glacier terminates in the ocean. As he climbed the slope, his boots slipped over rocks covered in penguin guano and dotted with dingy white feathers. Then, he came upon a series of ridges — rocks and pebbles that were piled up by waves during storms thousands of years before — that marked ancient shorelines.

Twelve thousand years ago, just as the last ice age was ending, this island would have been entirely submerged in the ocean. But as nearby glaciers shed billions of metric tons of ice, the removal of that weight allowed Earth’s crust to spring up like a bed mattress — pushing Lindsey 1 and other nearby islands out of the water, a few millimeters per year.

As Lindsey 1 rose, a series of shorelines formed on the edges of the island — and then were lifted, one after another, out of reach of the waves. By measuring the ages and heights of those stranded shorelines, the researchers could tell how quickly the island had risen. Because the rate of uplift is determined by the amount of ice being lost from nearby glaciers, this would reveal how quickly Pine Island and Thwaites glaciers had retreated — and whether they had gotten smaller than they are today and then readvanced.

Braddock dug into the pebbly ridges, collecting ancient cone-shaped limpet shells and marble-sized fragments of penguin bones deposited when the shorelines formed. Back in Maine, he and his colleagues radiocarbon dated those objects to estimate the ages of the shorelines. Ultimately, the researchers dated nearly two dozen shorelines, spread across several islands in the region.

These dates showed that the oldest and highest beach formed 5,500 years ago. Since that time, up until the last few decades, the islands have risen at a steady rate of about 3.5 millimeters per year. This is far slower than the 20 to 40 millimeters per year that the land around Pine Island and Thwaites is currently rising, suggesting that the rate of ice loss from nearby glaciers has skyrocketed due to the onset of rapid human-caused warming, after thousands of years of relative stability.

“We’re going into unknown territory,” Braddock says. “We don’t have an analog to compare what’s going on today with what happened in the past.”

Slawek Tulaczyk, a glaciologist at the University of California, Santa Cruz, sees the newly dated shorelines as “an important piece of information.” But he cautions against overinterpreting the results. While these islands are 100 kilometers from Pine Island and Thwaites, they are less than 50 kilometers from several smaller glaciers — and changes in these closer glaciers might have obscured whatever was happening at Pine Island and Thwaites long ago. He suspects that Pine Island and Thwaites could still have retreated and then readvanced a few dozen kilometers: “I don’t think this study settles it.”

CITATIONS

S. Braddock et al. Relative sea-level data preclude major late Holocene ice-mass change in Pine Island Bay. Nature Geoscience. Published online June 9, 2022. doi: 10.1038/s41561-022-00961-y.

SEE

https://plawiuk.blogspot.com/2022/06/polar-scientist-explains-peril-of.html

https://plawiuk.blogspot.com/2022/06/present-antarctic-deglaciation-may-be.html

FUND HEALTHCARE NOT COPS
How having health care workers handle nonviolent police calls may impact crime

The Denver pilot program in the study is one of many similar ones rolled out in recent years

In June 2020, Denver launched a pilot program to send trained health professionals (shown) rather than police officers in response to 911 calls for help involving nonviolent offenses, such as trespassing or disorderly conduct.         DENVER POLICE DEPARTMENT

By Sujata Gupta
JUNE 8, 2022 

For the last two years, a person acting erratically in downtown Denver has likely first encountered unarmed health care workers rather than police. That shift stems from the rollout of a program known as Support Team Assisted Response, or STAR, which sends a mental health clinician and paramedic to respond to certain 911 calls about nonviolent behavior.

The program, and others like it, aim to defuse the tensions that can arise when police officers confront civilians in distress. Critics of these experimental programs have suggested that such reduced police involvement could allow crime to flourish. 

Now, researchers have found that during its pilot phase, the STAR program did not appear to lead to more violent crime. And reports of minor crimes substantially decreased, the researchers conclude June 8 in Science Advances.

Much of that reduction occurred because the health responders do not issue citations or make arrests (SN: 12/18/21). But even that reduction in reported crime is beneficial, says economist Thomas Dee of Stanford University. “That person is getting health care instead of being arrested.”

Following the death of George Floyd at the hands of a white police officer and the subsequent rise of the Black Lives Matter movement in the summer of 2020, cities throughout the country have been rolling out programs like STAR. “We cannot police our way out of every social problem,” says Temitope Oriola, a sociologist at the University of Alberta in Edmonton, Canada. But so far there have been few studies of these programs’ effects on crime, let alone on the reduction of violence between police and the public (SN: 7/9/20).

Dee and Jayme Pyne, a sociologist also at Stanford, looked at the STAR program’s impact on crime reports. The duo investigated the program’s pilot phase, which ran from June to November 2020 and encompassed eight of the city’s 36 police precincts. Police officers and 911 operators in those eight precincts redirected calls for minor and non-dangerous complaints to STAR providers. These calls included concerns about trespassing, indecent exposure, intoxication and similar low-level offenses. During the six-month pilot, STAR providers responded to 748 calls, averaging roughly six incidents per eight-hour shift.

Dee and Pyne analyzed criminal offenses in all 36 precincts from December 2019 to November 2020. They then compared the change in crime rates in the eight precincts receiving STAR services with the change in crime rates in the other 28 precincts. The rate of violent crime remained unchanged across the board, including in the precincts where the STAR program was active, the researchers found. But there was a 34 percent drop in reports of minor offenses in the STAR precincts, from an average of about 84 offenses per month in each district to an average of about 56 citations.

The data also suggest that the actual level of minor crimes and complaints dropped too — that is, the drop wasn’t just due to a lack of reporting, the researchers say. Prior to the pilot, minor offenses in the eight precincts receiving STAR services resulted in an average of 1.4 citations per incident. So having health care workers rather than police respond to 748 such calls should generate roughly 1,000 fewer citations, the authors calculate. Instead, citations dropped by almost 1,400. Providing people in crisis with access to health services may be preventing them from reoffending, Dee says.

Research into these sorts of programs is crucial, says Michael Vermeer, a justice policy researcher with the RAND Corporation, a public policy research organization headquartered in Santa Monica, Calif. But he cautions against drawing firm conclusions from a single study launched at the onset of the COVID-19 crisis, which dramatically changed crime rates and patterns across the country. “They just got confounded by the pandemic,” Vermeer says.

Dee agrees that he and other researchers now need to replicate this study across more cities, and also scale up in Denver. The city has since expanded the STAR program beyond the initial pilot.

Even if researchers eventually find that STAR and similar programs don’t budge crime rates much, that doesn’t mean that the programs are unsuccessful, says sociologist Brenden Beck of the University of Colorado Denver. He points to the potential to save taxpayer dollars. Dee and Pyne estimate that a single offense processed through STAR costs about $150, compared with the roughly $600 it costs to process one through the criminal justice system.

What’s more, helping people having nonviolent mental health crises get help and stay out of jail lets these individuals hold onto their jobs and stay present in their family members’ lives, Beck says. “I would hope we as a research community move on to study the benefit of these programs not just in terms of crime but also in terms of human welfare.”

CITATIONS

T. Dee and J. Pyne. A community response approach to mental health and substance abuse crises reduced crime. Science Advances. Vol. 8, June 8, 2022. doi: 10.1126/sciadv.abm2106.

sciencenews.org

COSBY A RAPIST AND THAT IS THAT
Civil jury finds Bill Cosby sexually abused teenager in 1975


SANTA MONICA, Calif. (AP) — Jurors at a civil trial found Tuesday that Bill Cosby sexually abused a 16-year-old girl at the Playboy Mansion in 1975.

The Los Angeles County jury delivered the verdict in favor of Judy Huth, who is now 64, and awarded her $500,000.

“It’s been torture,” Huth said of the seven-year legal fight. “To be ripped apart, you know, thrown under the bus and backed over. This, to me, is such a big victory.”

Jurors found that Cosby intentionally caused harmful sexual contact with Huth, that he reasonably believed she was under 18, and that his conduct was driven by unnatural or abnormal sexual interest in a minor.

The jurors’ decision is a major legal defeat for the 84-year-old entertainer once hailed as America’s dad. It comes nearly a year after his Pennsylvania criminal conviction for sexual assault was thrown out and he was freed from prison. Huth’s lawsuit was one of the last remaining legal claims against him after his insurer settled many others against his will.

Cosby did not attend the trial or testify in person, but short clips from 2015 video deposition were played for jurors, in which he denied any sexual contact with Huth. He continues to deny the allegation through his attorney and publicist.

Cosby spokesman Andrew Wyatt said they would appeal and he claimed they had won because Huth didn’t win punitive damages.

Jurors had already reached conclusions on nearly every question on their verdict form, including whether Cosby abused Huth and whether she deserved damages, after two days of deliberations on Friday. But the jury foreperson could not serve further because of a personal commitment, and the panel had to start deliberating from scratch with an alternate juror on Monday.

Cosby’s attorneys agreed that Cosby met Huth and her high school friend on a Southern California film set in April of 1975, then took them to the Playboy Mansion a few days later.

Huth’s friend Donna Samuelson, a key witness, took photos at the mansion of Huth and Cosby, which loomed large at the trial.

Huth testified that in a bedroom adjacent to a game room where the three had been hanging out, Cosby attempted to put his hand down her pants, then exposed himself and forced her to perform a sex act.

Huth filed her lawsuit in 2014, saying that her son turning 15 — the age she initially remembered being when she went to the mansion — and a wave of other women accusing Cosby of similar acts brought fresh trauma over what she had been through as a teenager.

Huth’s attorney Nathan Goldberg told the jury of nine women and three men during closing arguments Wednesday that “my client deserves to have Mr. Cosby held accountable for what he did.”

“Each of you knows in your heart that Mr. Cosby sexually assaulted Miss Huth,” Goldberg said.

A majority of jurors apparently agreed, giving Huth a victory in a suit that took eight years and overcame many hurdles just to get to trial.

During their testimony, Cosby attorney Jennifer Bonjean consistently challenged Huth and Samuelson over errors in detail in their stories, and a similarity in the accounts that the lawyer said represented coordination between the two women.

This included the women saying in pre-trial depositions and police interviews that Samuelson had played Donkey Kong that day, a game not released until six years later.

Bonjean made much of this, in what both sides came to call the “Donkey Kong defense.”

Goldberg asked jurors to look past the small errors in detail that he said were inevitable in stories that were 45 years old, and focus on the major issues behind the allegations. He pointed out to jurors that Samuelson said “games like Donkey Kong” when she first mentioned it in her deposition.

The Cosby lawyer began her closing arguments by saying, “It’s on like Donkey Kong,” and finished by declaring, “game over.”

Huth’s attorney reacted with outrage during his rebuttal.

“This is about justice!” he shouted, pounding on the podium. “We don’t need game over! We need justice!”

The Associated Press does not normally name people who say they have been sexually abused, unless they come forward publicly, as Huth has.

___

AP Entertainment Writer Andrew Dalton contributed to this report.

Brian Melley, The Associated Press

FASCISTS HAVE NO RIGHT TO FREE SPEECH

Poilievre promises to protect freedom of speech on campus, appoint a 'Free Speech Guardian'

Catherine Lévesque - National Post

The idea of withholding federal funds from universities in order to protect free speech on campus is not new.

Conservative leadership hopeful Pierre Poilievre is threatening to remove direct federal research and other grants from Canadian universities if they do not commit to protect academic freedom and free speech from “campus gatekeepers.”

If he forms government, Poilievre promises to appoint a former judge which will act as a “Free Speech Guardian” who will ensure that universities respect the principles enshrined in the Charter of Rights and Freedoms, in particular section 2(b) which protects “freedom of thought, belief, opinion and expression.”

The former judge will be responsible for ensuring compliance by universities to these principles of academic freedom and free speech, but will also investigate claims of academic censorship.

Examples could include having pro-life or pro-Israel student groups cancel events or lose resources because of their different viewpoints, or having professors such as Jordan Peterson resign his post because of his “unacceptable philosophical positions” from his own account .


The “Free Speech Guardian” would be responsible for enforcing Poilievre’s policy by reporting to the federal government on universities’ breaches and for recommending reductions in direct federal grants to those that do not uphold the principles in the Charter. Federal-provincial transfers would not be affected by the free speech requirements.

Most support professor's use of racist language, in context: poll

U of T talk by anti-Israel activist tests Ontario’s campus free speech policy

There would, however, be limitations to Poilievre’s proposal. Hate speech will continue to be prohibited, as the courts have rules that it can be banned under the Charter.

“The Charter protects free speech, not hate speech, as explained by the Supreme Court of Canada. So does my academic freedom and free speech policy,” said Poilievre in a written statement to the National Post when asked for more specifics.

The idea of withholding federal funds from universities in order to protect free speech on campus is not new. In fact, former Conservative leader Andrew Scheer made this a promise during his own leadership campaign in 2017, and reiterated in his victory speech that “the foundation of our democracy is the ability to have a debate about any subject.”

But education remains a provincial jurisdiction and some provinces have already taken action to do just that.

In 2019, Ontario announced that all colleges and universities had developed, implemented and complied with a free speech policy while ensuring that hate speech and discrimination are not allowed on campus. Alberta also encouraged all publicly funded post-secondary institutions to adopt the Chicago Principles to encourage freedom of speech around that time.

More recently, Quebec adopted a law to enforce new rules around academic freedom across the province, ensuring that “any word” can be spoken in a university classroom as long as it is used in an academic context.

Quebec’s initiative was an indirect response to a University of Ottawa professor’s use of the N-word during a lecture that led to her suspension. The events played out differently in Ontario, where the province’s free speech policy had no effect, and in Quebec, where politicians of all stripes ran to the professor’s defence, invoking her right to use the derogatory word.

Poilievre’s campaign did not respond to followup questions regarding if his free speech policy would let a professor use the N-word in class for academic purposes.

Geneviève Tellier, a professor at the University of Ottawa who co-authored a book to denounce her colleague’s treatment at the time of her suspension, said that Ontario’s free speech policy was already in place when the events happened and did not change anything to the situation.

She seemed skeptical of Poilievre’s suggestion to have a national oversight, adding that it would only add another level of complexity.

“We already have a Free Speech Guardian. It’s the Charter of Rights and Freedoms,” said Tellier in an interview. “And we have the judicial system. Do we need something else? In my opinion, it would only add another administrative burden.”

She also added that Poilievre seems to mix up freedom of speech and academic freedom, stressing that universities do not exist to advance different agendas, but to advance knowledge.

That being said, it came as no surprise to the professor of political studies why the leadership candidate would tap into that theme as part of his campaign.

“Because there’s the word freedom. His whole campaign is driven by freedom.”

These tiny marsupials survived wildfires only to face extinction from feral cats

The Kangaroo Island dunnart was one species seen to reemerge after Australian bushfires

At about 7.5 centimeters long (not counting its tail), this Kangaroo Island dunnart — caught in 2022 during routine monitoring of the island’s wild inhabitants — easily fits in the palm of a hand.
PAT HODGENS


By Asa Stahl
JUNE 16, 2022 

Few marsupials have gone from miraculous survival to the brink of extinction as quickly as the Kangaroo Island dunnart.

In 2019 and 2020, devastating fires burned nearly 10 million hectares of southeastern Australia. The flames threatened hundreds of species with extinction, but the Kangaroo Island dunnart (Sminthopsis aitkeni) — which already numbered less than 500 before the fires — seemed to be one that defied expectations in the aftermath (SN: 3/9/21).

But now these rare creatures may be more at risk than ever, researchers say June 16 in Scientific Reports. The danger, as domestic as it sounds, is getting eaten by a cat.

As of 2008, invasive feral cats had contributed to at least 13 percent of extinctions worldwide. That’s one reason the government has been euthanizing cats on Kangaroo Island for years. The scientists who conducted the dunnart study knew all this — but when they studied the remains of cats euthanized in 2020, they were still surprised by what they saw: Seven out of 86 cats had recently dined on dunnart.

“We were not expecting to find so many,” says Louis Lignereux, a field researcher at the University of Adelaide School of Animal and Veterinary Science. It’s particularly bad news, he says, if you think of what was in the cats as only a snapshot of what they ate in the last 36 hours. Taking that into account, those seven cats alone could have eaten enough to wipe out the Kangaroo Island dunnart within a few months, if they had survived — and there are hundreds of other cats on the island.

A small habitat makes the dunnarts especially vulnerable. It’s like putting all your eggs in one basket, Lignereux says. Since the fires, the Kangaroo Island dunnart is thought to now live in an area about one-tenth of the size of Manhattan (SN: 1/13/20).

“If something happened to this spot,” he says, “then [the dunnart] is gone forever.”

Questions or comments on this article? E-mail us at feedback@sciencenews.org

CITATIONS

P. Hodgens et al. Cat predation of Kangaroo Island dunnarts in aftermath of bushfire. Scientific Reports. Published online June 16, 2022. doi: 10.1038/s41598-022-11383-6.

F.M. Medina et al. A global review of the impacts of invasive cats on island endangered vertebrates. Global Change Biology. Vol. 17, June 3, 2011, p. 3503–3510. doi: 10.1111/j.1365-2486.2011.02464.x.

About Asa StahlE-mail
Asa Stahl is the 2022 AAAS Mass Media fellow with Science News. He is a 5th year Astrophysics Ph.D. student at Rice University, where his research focuses on detecting and characterizing young stars and planets.

Western wildfires’ health risks extend across the country

Those fires devastating communities in the West send bad air traveling, boosting emergency room visits in the East

Western wildfires, like the 2018 Camp Fire in Paradise, Calif., are devastating for local communities. Their smoke also travels to heavily populated areas to the east. Researchers are beginning to study the health effects for people far from the fires.
JOSH EDELSON/AFP VIA GETTY IMAGES

By Megan Sever
JUNE 17, 2022

After a relaxing day at the Jersey Shore last July, Jessica Reeder and her son and daughter headed back home to Philadelphia. As they crested a bridge from New Jersey into Pennsylvania, they were greeted with a hazy, yellow-gray sky. It reminded Reeder of the smoky skies she saw growing up in Southern California on days when fires burned in the dry canyons.

Smelling smoke and worried about her asthma and her kids, Reeder flipped the switch to recirculate the air inside the car instead of drawing from the outside. At home, the family closed all the windows and turned their air purifiers on high.

The smoke had traveled from fires raging on the other side of the continent, in the western United States and Canada. Although air quality in Philadelphia didn’t come close to the record-bad air quality that some western cities experienced, it was bad enough to trigger air quality warnings — and not just for people with asthma or heart problems.

Most large U.S. wildfires occur in the West. But the smoke doesn’t stay there. It travels eastward, affecting communities hundreds to thousands of kilometers away from the fires. In fact, the majority of asthma-related deaths and emergency room visits attributed to fire smoke in the United States occur in eastern cities, according to a study in the September 2021 GeoHealth.

Smoke poured into the eastern United States and Canada from wildfires in the West on July 21, 2021 (darker red is denser smoke). Residents of eastern cities received code orange and code red warnings that air quality was unhealthy.

JOSHUA STEVENS/NASA EARTH OBSERVATORY

The big problem is fine particulate matter, tiny particles also known as PM2.5. These bits of ash, gases and other detritus suspended in smoke are no more than 2.5 micrometers wide, small enough to lodge in the lungs and cause permanent damage. PM2.5 exacerbates respiratory and cardiovascular problems and can lead to premature death. The particles can also cause asthma and other chronic conditions in otherwise healthy adults and children.

Over the last few decades, U.S. clean air regulations have cut down on particulate matter from industrial pollution, so the air has been getting cleaner, especially in the populous eastern cities. But the regulations don’t address particulate matter from wildfire smoke, which recent studies show is chemically different from industrial air pollution, potentially more hazardous to humans and increasing significantly.

So far, a lot of the research on how wildfire PM2.5 can make people sick has been based on people living or working near fires in the West. Now, researchers are turning their attention to how PM2.5 from smoke affects the big population centers in the East, far from the wildfires. One thing is clear: With the intensity and frequency of wildfires increasing due to climate change (SN: 12/19/20 & 1/2/21, p. 32), people across North America need to be concerned about the health impacts, says Katelyn O’Dell, an atmospheric scientist at George Washington University in Washington, D.C.

Bad air travels

Air pollution regulations limit PM2.5 from exhaust-emitting cars and trucks and fossil fuel–burning factories and power plants. These regulations have done “a really good job” reducing anthropogenic air pollution in the last couple of decades, says Rosana Aguilera, an environmental scientist at the Scripps Institution of Oceanography in La Jolla, Calif. In the United States, concentrations of six of the most common air pollutants have dropped by 78 percent since the Clean Air Act of 1970, according to the U.S. Environmental Protection Agency. PM2.5 concentrations have come down as well — at least until recently.

Western wildfires, which are growing more frequent, more severe and larger, are erasing some of the gains made in reducing industrial pollution, says Rebecca Buchholz, an atmospheric chemist at the National Center for Atmospheric Research in Boulder, Colo.

Fires in the Pacific Northwest are “driving an upward trend” in particulate matter air pollution, Buchholz and colleagues wrote April 19 in Nature Communications. Such smoke pollution peaks in August when fires in the region tend to spike and the atmosphere’s ability to clean itself through, say, rain, is limited. This spike of late-summer air pollution is new, Buchholz says. It’s especially noticeable since 2012.

New York City, visible through hazy skies in September 2020, and many places in the East have seen some of the worst air quality in decades due to fires burning in the U.S. West and in Canada. Such fires are increasing in intensity and frequency.

GARY HERSHORN/GETTY IMAGES PLUS

And, as Reeder and her family experienced last year, transported wildfire pollution is causing substantial particulate matter spikes in the central United States and northeastern North America, Buchholz and colleagues found. Pacific Northwest wildfires thus “have the potential to impact surface air quality, even at large distances downwind of the wildfires,” the team wrote, putting some 23 million people in the central United States and 72 million in northeastern North America at increased risk of health impacts from the imported wildfire smoke.

How far and where PM2.5 travels depends on weather patterns and how high wildfire smoke reaches — the stronger the fire, the longer it can last and the farther smoke can go, and thus the farther particulate matter can reach. Last year, far-away wildfires created unhealthy air quality conditions in locations from the Great Plains to New York City and Washington, D.C.

New York City saw some of its worst air quality in two decades. Philadelphia had two “code red” days — meaning air quality was unhealthy for all — because of the U.S. West and Canadian fires. In 2019, 2020 and 2021, those fires pushed PM2.5 to unhealthy levels in much of Minnesota. In fact, a 2018 study showed that wildfire smoke plumes now waft above Minnesota for eight to 12 days per month between June and September.

Air safety yardstick

The Air Quality Index, or AQI, ranges from 0 to 500, based on the amount of pollution in the air at a given time. Ground-level ozone, particulate matter (both PM10 and PM2.5), carbon monoxide, sulfur dioxide and nitrogen dioxide are the primary parameters considered in the index. Code orange (above a score of 100) is unhealthy for people with heart and lung disease, older adults, children and people with diabetes. Code red and above (151–500) is unhealthy for everyone.

T. TIBBITTS

Human impacts

Smoke in the West is already having a tangible effect on human health in the East, says O’Dell, lead author of the 2021 GeoHealth study.

Reviewing smoke and health data from 2006 to 2018, O’Dell and colleagues found that more people visit emergency rooms and are hospitalized in the East than in the West from asthma problems attributable to smoke PM2.5. Asthma-related ER visits and hospitalizations were higher east of the Rockies in 11 of the 13 years.

Over the study period, an average of 74 percent of asthma-related deaths and 75 percent of asthma ER visits and hospitalizations attributable to smoke occurred east of the Rockies. Of the estimated 6,300 excess deaths from asthma complications due to smoke PM2.5 that occurred annually over the study period, more than 4,600 were in the East.

Smoke affects so many more people in the East primarily because more people live there, O’Dell notes. Her team defined “West” as west of the Rockies, with a population of 64 million, and “East” as east of the Rockies, home to 226 million people. In the West, smoke PM2.5 causes a higher portion of regional asthma deaths. In the East, it’s a lower portion of the total population, but a far higher total number of people affected.

“We may be already seeing the consequences of these fires on the health of residents who live hundreds or even thousands of miles downwind,” Buchholz said in a press release.

August peaks

Although aerosols, including fine particulate matter, from Pacific Northwest fires have been increasing since 2002, they began a sharp increase in 2012, spiking in the warm, dry summer months. As smoke from the Northwest wafted eastward, similar smaller spikes were seen in the central United States and northeastern North America.
North American seasonal atmospheric aerosol levels, by region

R.R. BUCHHOLZ ET AL/NATURE COMMUNICATIONS 2022 (CC BY 4.0)

Vulnerable youth

“Asthma is a very widespread, common health condition,” says Yang Liu, an environmental scientist at Emory University in Atlanta. In the United States, about 25 million people have asthma, or 8 percent of adults and 7 percent of children, according to the U.S. Centers for Disease Control and Prevention.

Fine particulate matter can spark asthma attacks, but it can also be a danger to people without the condition. Children are especially vulnerable primarily because of physiology. Children breathe faster so they end up taking in more particulate matter, plus their lungs are smaller so more of their lung surface is likely to be damaged when they breathe in particulate matter. And their lungs are still developing, says Jennifer Stowell, an environmental epidemiologist at Boston University School of Public Health.

Stowell led a study, reported in the January Environmental Research Letters, estimating how much wildfire smoke will exacerbate asthma attacks in the West. Stowell, Liu and colleagues estimate that, in the 2050s, there will be an additional 155,000 asthma-related ER visits and hospitalizations per wildfire season in the West just from smoke PM2.5. The biggest concern, Stowell says, is for children and younger adults.

Aguilera, of Scripps, and her colleagues found associations between wildfire-specific PM2.5 and pediatric respiratory-related ER and urgent care visits. In San Diego County from 2011 to 2017, wildfire-specific PM2.5 was 10 times as harmful to respiratory health in children 5 and younger as ambient PM2.5, the researchers reported in 2021 in Pediatrics. In fact, the same increase in levels of PM2.5 from smoke versus ambient sources caused a 26 percent higher rate of ER or urgent care visits. The researchers didn’t note whether the children had preexisting asthma.

And even when a wildfire increased PM2.5 by a small amount, respiratory ER and urgent care visits in kids 12 and under increased, Aguilera and colleagues reported in 2020 in the Annals of the American Thoracic Society. “Even relatively smaller wildfires can still generate quite an impact on the pediatric population,” Aguilera says. “And really, any amount of PM or air pollution is harmful.”

Studies of nonhuman primates have also shown permanent effects of smoke on the young — results researchers expect would also apply to humans, given genetic similarities. In 2008, a group of infant rhesus macaques at the California National Primate Research Center at the University of California, Davis was exposed to high PM2.5 levels from a series of devastating wildfires in Northern California. Researchers have been comparing those monkeys with macaques born a year later that weren’t exposed to smoke.

At the California National Primate Research Center, rhesus macaques that were exposed to wildfire smoke early in life have immune disorders, nervous system changes and weakened lungs.

© 2014 KATHY WEST/CALIFORNIA NATIONAL PRIMATE RESEARCH CENTER/UC DAVIS

At around age 3, macaques exposed to smoke displayed immune disorders and reduced lung capacity, lung function and lung volume, says Hong Ji, a molecular biologist at UC Davis and the primate center who wasn’t involved with this study. The lungs look like they had fibrosis, Ji says. “Early life smoke exposure … changed the trajectory of lung development,” and it doesn’t appear to be reversible, she says.

The monkeys exposed to wildfire PM2.5 also have important changes to how their DNA works, Ji and colleagues reported in the January Environment International. Exposure to wildfire smoke in infancy can cause life-altering, long-term changes to the monkeys’ nervous and immune systems, as well as brain development, Ji says. Even worse, she says, the DNA changes are the type that can be passed down and may result in generational damage.

Even macaques born after in utero exposure to wildfire smoke can suffer cognitive, immune and hormone problems, primate center researchers reported April 1 in Nature Communications.

Now, Ji and colleagues have teamed with Rebecca Schmidt, a molecular epidemiologist at UC Davis who’s leading a study on the effects of wildfire smoke exposure on pregnant women and young children. This research group, as well as other teams, is also looking into whether PM2.5 is causing genetic changes to babies exposed to smoke in utero, Ji says. The more results gathered on the effects of wildfire PM2.5 on babies and children — and even in pregnancy — the more dangerous we realize it is, Ji says.

Chemical differences

Particulate matter changes as it travels through the atmosphere, both in volume and in chemistry. Some PM2.5 is emitted directly from fires, and some is born from chemicals and trace gases emitted from fires that get chemically processed in the atmosphere, Buchholz says. Reactions that happen in the smoke plume, combined with sunlight, can create even more PM2.5 downwind of the fires. How these particulates change chemically — through interactions between the atmosphere and the particulate matter, and between fire pollution and human pollution — and what that means for human health “is a really active area of research right now,” she says. “It’s super complicated.”

Epidemiological and atmospheric chemistry studies indicate that wildfire PM2.5 is more hazardous to human health than ambient PM2.5, says Stowell, the Boston epidemiologist. One such study compared particulate matter from Amazonian fires with urban sources such as vehicle exhaust in Atlanta. Nga Lee Ng, an atmospheric chemist at Georgia Tech, and colleagues found that smoke particulate matter is more toxic than urban particulate matter, “inducing about five times higher cellular oxidative stress,” Ng says. Oxidative stress damages cells and DNA in the body.

In addition, as smoke travels through the atmosphere and ages, it seems to become even more toxic, Ng says. Reactions between the particulate matter and sunlight and atmospheric gases change the particulate matter’s chemical and physical properties, rendering it even more potentially harmful. So, even though particulate matter dissipates over time and distance, “the health effects per gram are greater,” says Daniel Jaffe, an atmospheric chemist at the University of Washington Bothell.

That means that the studies of health effects near wildfires in the West may not represent the full story of how smoke from distant fires affects people in the East.

Liu, at Emory, hopes to see the U.S. government revisit policies related to what PM2.5 levels are dangerous, since they’re based on ambient and not wildfire-related PM2.5. In March, an EPA advisory panel recommended just that. In a letter to the agency, the Clean Air Scientific Advisory Committee wrote: “Regarding the annual PM2.5 standard, all CASAC members agree that the current level of the annual standard is not sufficiently protective of public health and should be lowered.” The committee added, “There is substantial epidemiologic evidence from both morbidity and mortality studies that the current standard is not adequately protective.”

Local communities throughout the country need to determine when to close schools or at least keep kids inside, Liu says, as well as when to advise people to close windows and turn on air purifiers. Good masks — N95 and KN95 — can help too (yes, masks that block viruses can also block particulate matter).

City, county and state governments also need to prepare the health care system to respond to increased asthma issues, Liu says. Some states are starting to respond. In 2017, for example, the Minnesota Pollution Control Agency increased its air quality monitoring stations around the state from two to 18. The agency is also working with the National Weather Service, the Minnesota Department of Health and the Minnesota Department of Transportation to better communicate air quality warnings.

Minnesota, after experiencing a rise in smoky summer days, has added extra air quality monitoring stations to improve local forecasts.

MINNESOTA POLLUTION CONTROL AGENCY

In the meantime, much more research is needed into the human health implications of increasing wildfire smoke, Buchholz says, as well as the chemical interactions in the atmosphere, how climate is changing fires, how fires change year after year, and how they impact the atmosphere, not to mention how different trees, buildings and other fuels affect particulate matter.

“Wildfires are perhaps one of the most visible ways that [climate change] is linked to health,” Stowell says. And the reality is, she says, “we’re going to see it remain as bad or worse for a while.”

Smoke gets on the brain

Health impact studies of air pollution, including wildfire smoke, have mostly focused on the lungs. But toxicologist Matthew Campen of the University of New Mexico in Albuquerque is looking at the brain.

In a study of the inflammatory effects of smoke PM2.5 on the brains of mice, Campen and colleagues found that inflammation in the lungs was modest compared with the “profound” inflammation in the brain, Campen says. Given what’s known about how damaging smoke can be in the lungs, to find even greater effects on the brain is troubling, he says.

The inflammatory effect on the mice’s brains was almost immediate, within 24 hours of exposure, the researchers reported in the March Toxicological Sciences. The particulates enter the body through the respiratory system, get in the blood, and are small enough to cross the blood-brain barrier and start affecting the brain. Inflammation has been linked with dementia in older people and neurodevelopmental issues in younger people, plus mood disorders like anxiety and depression, Campen says.

“I’m hoping that our study with mice spurs … epidemiologists to take a look,” he says. “The effects we see are much stronger and more worrisome than what we see in the lungs,” he says, but we don’t know yet at what PM2.5 levels the danger begins. “We need to explore this more rigorously.” — Megan Sever

A version of this article appears in the June 18, 2022 issue of Science News.

CITATIONS

R.R. Buchholz et al. New seasonal pattern of pollution emerges from changing North American wildfires. Nature Communications. Vol. 13. April 19, 2022. doi:10.1038/s41467-022-29623-8.

J.D. Stowell et al. Asthma exacerbation due to climate change-induced wildfire smoke in the Western US. Environmental Research Letters. Vol. 17. January 2022. doi:10.1088/1748-9326/ac4138.

R. Aguilera et al. Fine particles in wildfire smoke and pediatric respiratory health in California. Pediatrics. Vol. 147. April 2021. doi:10.1542/peds.2020-027128.

A.P. Brown et al. Long-term effects of wildfire smoke exposure during early life on the nasal epigenome in rhesus macaques. Environment International. Vol. 158. January 2022. doi:10.1016/j.envint.2021.106993.

D. Scieszka et al. Neuroinflammatory and neurometabolomic consequences from inhaled wildfire smoke-derived particulate matter in the western United States. Toxicological Sciences. Vol. 186. March 2022. doi:10.1093/toxsci/kfab147.


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WAR IS ECOCIDE

Russia’s invasion could cause long-term harm to Ukraine’s prized soil
Physical and chemical damage to farmland could linger for years

A team works to destroy an unexploded missile in a field near Hryhorivka, Ukraine. War damage done to the country’s fertile soil could affect agriculture for years.
DIMITAR DILKOFF/AFP VIA GETTY IMAGES

By Rebecca Dzombak
JUNE 21,2022

By now, wheat planted late last year waves in fields across Ukraine. Spring crops of sunflowers and barley are turning swaths of dark earth into a fuzz of bright green. But with Russia’s war being waged in some of the most fertile regions of Ukraine, uncertainty looms over summer harvesting.

Ukrainian farmers braved a war zone to carry out close to 80 percent of spring planting, covering roughly 14 million hectares. Still, Russia’s invasion has raised fears that not only are this year’s crop yields in jeopardy, but also that Ukraine’s agricultural output could be diminished for years. At the root of this worry, in part, is how warfare impacts soil.

Ukraine is home to some of the most fertile soil in the world, making it a top global producer of cereals, such as wheat and maize, as well as seed oils like sunflower oil. The country’s exports feed millions of people from Europe and Africa to China and Southeast Asia.

With the war in its fourth month, the Food and Agriculture Organization of the United Nations estimates at least 20 percent of Ukraine’s crops planted in winter will remain unharvested or went unplanted. And despite farmers’ best efforts, many spring crops went unplanted. This summer’s winter wheat harvest could be cut approximately in half (a loss of about 2 million hectares) and sunflower products cut by a third.

With warfare able to degrade and contaminate soil for years, crop yields — and the people who depend on them — could suffer long after a cease-fire.

“In many ways, the welfare of the soil system in postwar nations is really intricately tied to the welfare of the people,” says soil scientist Asmeret Asefaw Berhe of University of California, Merced. “And in many ways, it’s going to dictate their long-term future, too.”
Super soil

A type of grassland soil called chernozem covers nearly two-thirds of agricultural lands in Ukraine. Meaning “black earth,” chernozem is a Ukrainian and Russian word that describes highly fertile soils distinguished by one to two meters of dark, rich organic matter. Over the last 10,000 years, it accumulated along the Eurasian steppes, slowly building up as a black bed atop fine, windblown sediments called loess, which coated the region as the glaciers retreated. At the same time in North America, grassland soils similar to chernozems called mollisols formed over the Great Plains, creating twin breadbaskets.

Chernozem (shown) is nutrient-rich dark soil that is essential for agriculture in Ukraine.

SOIL MUSEUM/SOIL EDUCATION CENTER/UNIVERSITY OF AGRICULTURE IN KRAKÓW, COURTESY OF PIOTR PACANOWSKI

Chernozems are rich in elements that plants need to grow, such as nitrogen, potassium and calcium. Those nutrients come from organic matter and underlying loess. Chernozems also hit the sweet spot of clay content — just enough to help hold the soil together and cling onto nutrients but not so much that roots have a hard time penetrating the ground.

In their natural state, chernozems come preloaded with vitamins and minerals, like a super-smoothie of plant nutrition. “Plants growing in these soils are lucky,” Berhe says. “They’re growing in an environment that has everything they need to grow, with or without additional fertilizers or extra supplements.”
Bombing fields

There’s a term for what war does to soil: bombturbation. It’s grim wordplay on the natural process of bioturbation — earthworms and other animals stirring up soil. In this case, though, exploding bombs and artillery fire fling clods of dirt and dig craters. Joseph Hupy, a soil geomorphologist at Purdue University in West Lafayette, Ind., coined the term with coauthor Randall Schaetzl in 2006 while studying soils’ battlefield scars.

At France’s World War I battlefield at Verdun, Hupy dug meter-long trenches with a backhoe across bomb craters and in their vicinity, looking for signs of disturbance. He wanted to understand how the landscape recovered, with or without human help. He found decades-old chaos beneath the surface. His cross sections revealed rubble, chunks of limestone bedrock embedded in a slurry of sandy soil and organics. That chaos was reflected on the surface too: Where there were craters, water flow had changed, leading to different patterns of vegetation growth, Hupy and a colleague reported in 2012 in Geomorphology. Because of shifts in hydrology and a lack of human management, the landscape reverted from agriculture to forest. “It’s a completely new ecosystem,” he says.

Shelling left a deep crater in a field on the outskirts of Kharkiv, Ukraine. This type of damage can change vegetation growth.

BERNAT ARMANGUE/AP PHOTO

Hupy noted similar changes at Vietnam’s Khe Sanh, which the United States heavily bombed in 1968. Aerial images of Ukrainian battle zones show pockmarked fields, reminiscent of the sites Hupy studied in Vietnam. Problems in Ukrainian soil may not be limited to the surface. Even if farmers smooth over the top of the soil, underground rubble can act like a barrier or sluice for water, which could make it harder to grow crops.

When there’s a highly compacted area beneath where the teeth of a plow can go, that impermeable layer of soil “can create standing water, and all other sorts of problems from an agricultural standpoint,” Hupy says.

Trouble with tanks

Bombs may leave some of the most obvious impacts, but they aren’t the only thing that can physically disturb soil. Soggy, thawing soils in Ukraine bogged down Russian tanks as if a metaphor of resistance: The land itself was fighting back. But what’s bad for invading tanks is also bad for the soil. When tanks roll over a field, their weight makes soil clump and stick together. Wet soil can compound the problem, exacerbating compaction. And chernozems are particularly vulnerable to compaction: With their thick layer of organic matter, they’re fluffy and light.

Compaction can temporarily cut crop yields by anywhere from 10 percent to nearly 60 percent because it makes it more difficult for roots to reach nutrients and prevents water and fertilizers from penetrating the soil. A study in International Agrophysics on compaction and crop yields in Eastern European chernozems, for instance, found chernozem-grown barley plants yielded about half the amount of crops when highly compacted. Earlier work suggested compaction could impact yields for up to five years if it reached deep enough into the chernozem. For all but the worst compaction, though, several seasons of typical planting will help heal the land, says soil scientist DeAnn Presley of Kansas State University in Manhattan.

“If you had tank traffic go right through a crop field, the farmer is probably going to go out and just till up the field pretty well after the conflict is over. And you may never see that [compaction] again,” Presley says. Compaction “will definitely look terrible and you’ll have yield losses, but I don’t think they’ll be forever or permanent.”

Outside Kharkiv, a destroyed Russian tank sits in a field. Tanks can pack down the fluffy chernozem soil and that compaction can cut crop yields.

DIMITAR DILKOFF/AFP VIA GETTY IMAGES

A study of military vehicles rolling over prairie soils outside Fort Riley, Kan., revealed it took as little as one year for dry soil to recover from being compacted, but up to four years for wet soil to recover, both without tilling, scientists reported in Soil Science Society of America Journal. Tank traffic can alter the community of soil microbes and reduce the abundance of other organisms, like soil-aerating earthworms, for several years as well, members of the same team reported in Applied Soil Ecology.

Chernozems’ fluffiness might put it at greater risk of compaction, but it can also help the soil spring back afterward, helping prevent it from becoming a longer-term problem. Hardy, deep-rooting plants like some of Ukraine’s native grasses could also loosen stubborn soils, Presley says, but it would take years.

Chemical contamination

Countering compaction can be a relatively quick fix; not so with chemical contamination. Fuel spills, spent ammunition, chemical weapons, and animal and human remains can all foul the soil, sometimes for decades or longer.

Potentially toxic metals such as lead, arsenic and mercury can leach out of ammunition and weaponry and into the soil. Pollutants from warfare are still found in soils contaminated by wars as old as World War I, researchers reported in 2020 in Sustainability. At Ypres, a World War I battlefield in Belgium, scientists estimate that shells and artillery left more than 2,800 metric tons of copper in the top half-meter of soil. In Iran, soils remain laced with mercury and chlorine from the 1980s.

As crops grow, they can draw up these potentially toxic elements. Other elements, such as zinc and nickel, can severely stunt crop growth, says Ganga Hettiarachchi, a soil chemist also at Kansas State University. But soil contamination can be a hidden danger. If it doesn’t damage the plants, there may be no way of knowing if the soil is contaminated without careful testing, she says.

In some ways, chernozems are well-equipped to stop contaminants in their tracks in a matter of months. The soil’s organic matter and clay can trap toxic elements before they can enter a plant, sucking out contaminants – even in a matter of days in optimal lab conditions, Hettiarachchi says. But in real life, many chernozems are also slightly acidic, which can let those elements stay in a form that plants can take up for months before being stopped.

Because of this uncertainty, every potentially contaminated patch of soil must be checked to see if crops can be safely grown. “We have to monitor the soil and the crops as well, at least until we understand what’s going on,” says Hettiarachchi.

Potentially toxic metals can leach out of munitions, such as this rocket a team is working to remove from a field in Borodianka, Ukraine. Ridding the country of this weaponry could take decades.

CHRISTOPHER FURLONG/GETTY IMAGES

For some elements, farmers could remediate by planting plants known to extract those elements over time, says Hettiarachchi, but that would require several years of planting. Other options include altering the soils’ pH to lock away metals or adding extra fertilizer, which can also immobilize potentially toxic elements. But even after remediation occurs, farmers must test to see if soil conditions are keeping the contaminants locked away, or if the war is coming back to haunt them from the ground.

Depending on the extent of contamination, “it might not be possible for Ukrainian farmers to avoid growing in contaminated soils,” she says. Soil testing and time will tell.
Looking toward the future

With Russia’s bombardment of Ukraine still ongoing, the effect on the country’s soil is still uncertain. There are some hints, though. This isn’t the first time the Donbas region — a disputed area in eastern Ukraine — has come under fire. Russian-backed separatists attacked it beginning in 2014 too.

Scientists working in the Donbas to improve soil health there have faced a litany of challenges: The region’s agriculture already suffered from degradation due to irrigation waters polluted by coal mines, researchers reported in 2020 in Mineralogical Journal. Decades of intense farming had also taken a toll. Since 2014, conflict has exacerbated those problems, creating new issues and hampering scientists’ ability to help.

The region’s “chernozems have suffered and are experiencing irreparable military degradation,” Ukrainian soil scientists and a lawyer wrote in 2021 in Scientific Papers. Series A. Agronomy. “It is easy to predict [the degradation of chernozems], but very difficult to overcome.”

Even as the fighting has been concentrated in eastern Ukraine, this assessment now may apply to a far broader swath of the country. “Our unique soils, chernozems, are in unprecedented conditions,” representatives from Ukraine’s Institute for Soil Science and Agrochemistry Research wrote Science News in an e-mail. “The extent of the damage has yet to be ascertained. In fact, we have just begun to work in this direction … in difficult military conditions.”

CITATIONS

J.P. Hupy and R.J. Schaetzl. Introducing “bombturbation,” a singular type of soil disturbance and mixing. Soil Science, Vol. 171, November 2006, p. 823. doi: 10.1097/01.ss.0000228053.08087.19.

J.P. Hupy and R.J. Schaetzel. Soil development on the WWI battlefield of Verdun, France. Geoderma. Vol. 145, May 2008, p. 37. doi: 10.1016/j.geoderma.2008.01.024.

J.P. Hupy and T. Koehler. Modern warfare as a significant form of zoogeomorphic disturbance upon the landscape. Geomorphology. Vol. 157-158, July 2012, p. 169. doi: 10.1016/j.geomorph.2011.05.024.

M.F. Nawaz, G. Bourrié and F. Trolard. Soil compaction impact and modelling. A review. Agronomy for Sustainable Development. Vol. 33, January 31, 2012, p. 291. doi: 10.1007/s13593-011-0071-8.

J. Lipiec et al. Effect of soil compaction on root growth and crop yield in Central and Eastern Europe. International Agrophysics. Vol. 17, 2003, p. 61. YADDA: bwmeta1.element.agro-article-486b0405-0d68-4f7a-9782-3fd0415d847e.

P.S. Althoff, S.J. Thien and T.C. Todd. Primary and residual effects of Abrams tank traffic on prairie soil properties. Soil Science Society of America Journal. Vol. 74, November 2010, p. 2151. doi: 10.2136/sssaj2009.0091.

P.S. Althoff et al. Response of soil microbial and invertebrate communities to tracked vehicle disturbance in tallgrass prairie. Applied Soil Ecology. Vol. 43, September 2009, p. 122. doi: 10.1016/j.apsoil.2009.06.011.

V.A. Korolev. Specific features of water permeability in virgin and cultivated chernozems. Eurasian Soil Science. Vol. 40, September 2007, p. 962. doi: 10.1134/S1064229307090062.

P. Broomandi et al. Soil contamination in areas impacted by military activity: A critical review. Sustainability. Vol. 12, 2020, p. 9002. doi: 10.3390/su12219002.

M. Van Meirvenne et al. Could shelling in the First World War have increased copper concentrations in the soil around Ypres? European Journal of Soil Science. Vol. 59, April 2008, p. 372. doi: 10.1111/j.1365-2389.2007.01014.x.

N.O. Ryzhenko, S.V. Kavetsky and V.M. Kavetsky. Heavy metals (Cd, Pb, Zn, and Cu) uptake by spring barley in polluted soils. Polish Journal of Soil Science. Vol. 48, 2016, p. 111. doi: 10.17951/pjss.2015.48.1.111.

V.O. Pryvalov, O.A. Panova and A.V. Pryvalov. Geology in environmental management issues of the Donbas within the context of its forthcoming restoration. Mineralogical Journal. Vol. 42, 2020, p. 76. doi: 10.15407/mineraljournal.42.01.076.

S. Pozniak, N. Havrysh and T. Yamelynets. Chernozems of Ukraine and its evolution under the influence of anthropogenic factors. Scientific Papers. Series A. Agronomy.Vol. 64, 2021, p. 156.

J.P. Hupy. Khe Sanh, Vietnam: Examining the long-term impacts of warfare on the physical landscape. Chapter in Modern Military Geography. Routledge, 2010.

Meteorite Discovery Challenges Our Understanding of How Mars Formed

Sirenum Fossae on Mars. (NASA)


MICHELLE STARR
20 JUNE 2022

A small chunk of rock that once broke away from Mars and found its way to Earth may hold clues that reveal surprising details about the red planet's formation.

A new analysis of the Chassigny meteorite, which fell to Earth in 1815, suggests that the way Mars obtained its volatile gasses – such as carbon, oxygen, hydrogen, nitrogen, and noble gasses – contradicts our current models about how planets form.

Planets are born, according to current models, from leftover star stuff. Stars form from a nebular cloud of dust and gas when a dense clump of material collapses under gravity. Spinning, it spools in more material from the cloud around it to grow.

This material forms a disk, whirling around the new star. Within that disk, dust and gas begin to clump together in a process that grows a baby planet. We've seen other baby planetary systems forming in this way, and evidence in our own Solar System suggests it formed the same way, around 4.6 billion years ago.

But how and when certain elements were incorporated into the planets has been tricky to piece together.

According to current models, volatile gasses are taken up by a molten, forming planet from the solar nebula. Because the planet is so hot and mushy at this stage, these volatiles are slurped into the global magma ocean that is the forming planet, before later being partially outgassed into the atmosphere as the mantle cools.

Later, more volatiles are delivered via meteorite bombardment – volatiles bound up in carbonaceous meteorites (called chondrites) are released when these meteorites break apart on introduction to the planet.

So, the interior of a planet should reflect the composition of the solar nebula, while its atmosphere should reflect mostly the volatile contribution of meteorites.

We can tell the difference between these two sources by looking at ratios of isotopes of noble gasses, particularly krypton.

And, because Mars formed and solidified relatively quickly in about 4 million years, compared to up to 100 million years for Earth, it's a good record for those very early stages of the planetary formation process.

"We can reconstruct the history of volatile delivery in the first few million years of the Solar System," said geochemist Sandrine Péron, formerly of the University of California Davis, now at ETH Zurich.

That is, of course, only if we can access the information we need – and this is where the Chassigny meteorite is a gift from space.

Its noble gas composition differs from that of the Martian atmosphere, suggesting that the chunk of rock broke away from the mantle (and flung into space, precipitating its arrival at Earth), and is representative of the planetary interior and thus the solar nebula.

Krypton is quite tricky to measure, however, so the precise isotope ratios have eluded measurement. However, Péron and her colleague, fellow geochemist Sujoy Mukhopadhyay of UC Davis, employed a new technique using the UC Davis Noble Gas Laboratory to perform a new, precise measurement of krypton in the Chassigny meteorite.

And this is where it got really weird. The krypton isotope ratios in the meteorite are closer to those associated with chondrites. Like, remarkably closer.

"The Martian interior composition for krypton is nearly purely chondritic, but the atmosphere is solar," Péron said. "It's very distinct."

This suggests that meteorites were delivering volatiles to Mars much earlier than scientists previously thought, before the solar nebula had been dissipated by solar radiation.

The order of events, therefore, would be that Mars acquired an atmosphere from the solar nebula after its global magma ocean cooled; otherwise, the chondritic gasses and the nebular gasses would be much more mixed than what the team observed.

However, this presents another mystery. When solar radiation did eventually burn away the remnants of the nebula, it ought to have burnt away the nebular atmosphere of Mars, too. This means that the atmospheric krypton present later must have been preserved somewhere; perhaps, the team suggested, in polar ice caps.

"However, that would require Mars to have been cold in the immediate aftermath of its accretion," Mukhopadhyay said.

"While our study clearly points to the chondritic gasses in the Martian interior, it also raises some interesting questions about the origin and composition of Mars' early atmosphere."

The team's research has been published in Science.