Optional Homework ArticleWeek Six – November Fifth to Eighth

Read the article below and choose ONE of the three response options to complete. If you achieve mastery, it will be added to your personal management grade

Response Option 1 – Sum it UpWrite a paragraph summarizing the article in your own words. If you include quotations, please cite them correctly.

Response Option 2 – Share it Out Prepare a 2-5 minute presentation to share with the class summarizing what the article was about and explaining relevant details.

Response Option 3 – Language LearningHighlight 3-6 words in the article that are new to you. On a separate piece of paper, list the words in a chart like this one: Term Definition - Guess Definition - Actual

Fill in your guess about the definition of the words based on the article, and fill in the definitions you look up from a credible source. Include where you found the information.

Science works to save a salty world treasure

Water and pollution threaten Poland’s 700-year-old World Heritage Site

KATHIANN KOWALSKI

NOV 9, 2017 — 6:45 AM EST

Most of the items in this impressive room were carved from salt. Scientists are working to

preserve them and other parts of the Wieliczka Salt Mine in Poland.

JAROPIENZA/ISTOCKPHOTO

WIELICZKA, Poland — Shining a flashlight, Marek Klimowicz [KLEE-moh-veech] leads me

through a dimly lit tunnel. Old wooden timbers support the roof and walls of rock. The

tunnel leads us to a warren of rooms large and small. With few exceptions, Klimowicz says,

“Everything here is salt.”

There’s salt above us. We walk on a floor of salt. Just an arm’s length away are walls of salt.

In all, this underground warren contains some 2,000 chambers. They span a vast 7 million

cubic meters (265 million cubic feet). That’s nearly triple the volume inside the Great

Pyramid of Giza in Egypt. And it’s almost twice the volume of the NASA Vehicle Assembly

Building, where huge rockets were built, in Florida.

We’ve just gone down 380 stairs to a chamber 64 meters (210 feet) underground. Our

depth is more than the height of a buried 19 story building! Over the next two hours, we’ll

trek down another 400 stairs, more than doubling our depth. Some rooms are small, others

the size of ballrooms or cathedrals.

Just 15 kilometers (9 miles) from Kraków, Poland, we’re traveling through an eerie

subterranean world. Its formal name is the Wieliczka and Bochnia Royal Salt Mines. To

most people, it’s simply Wieliczka [Vee-LEETS-

kuh].

Even crystals in the chandeliers at the

Wieliczka mine are made of salt.

K.M. Kowalski

For seven centuries, miners hauled salt from its

depths. Before refrigeration, that salt helped

preserve foods. It added flavor. And it

provided a needed nutrient in the diet. Today

salt has many additional uses. For instance, it melts ice on roads, treats hard water and

helps make paper.

Mining here was hard and dangerous. In the 1500s and 1600s, one in every 10 miners each

year died in methane explosions. So the mine, both beautiful and perilous, evoked

reverence from its workers. Many began carving people, biblical scenes and more in its salt.

Although most mining ended here a bit more than 20 years ago, this is no 700-year-old

derelict. Quite the opposite. The mine also runs a spa offering salty treatments. And its

many carvings have gained world renown. Roughly a million people visit Wieliczka each

year to view this art.

Indeed, that’s one reason the United Nations Educational, Scientific and Cultural

Organization — or UNESCO — has designated Wieliczka a World Heritage site. That

means it’s so special to the cultural and natural heritage of people around the world that it

must be preserved as one of the “irreplaceable sources of life and inspiration.”

Already, more than 1,000 sites have earned this distinction. They range from the Pyramids

of Egypt and Great Barrier Reef to East Africa’s Serengeti and England’s Stonehenge to the

Statue of Liberty in New York City and Mammoth Cave National Park in Kentucky.

Wieliczka was one of the first 12 sites added to the list as it was first being drawn up in

1978.

Today some of the Wieliczka’s rooms serve as a museum. Many host beautifully carved,

centuries-old statues. There’s even an underground church. But UNESCO also cares about

this site because it faces threats.

For years, moisture — from Mother Nature together with the exhaled breaths of awed

visitors — has been eating away at the site’s salty treasures. And that’s where science

comes in. Researchers also have been studying this unique spot to better understand how it

developed and survived for so long. They hope that what they learn will allow it to persist

for many centuries to come.

Salt is a famous food preservative, but scientists now need to figure out how to preserve

the salt itself.

A crystalline world

Legend credits a Hungarian princess named Kinga with finding this massive salt deposit in

the 1200s. She was engaged to a Polish prince, Bolesław [BOH-leh-swahv]. On her way to

Poland to marry the prince, she stopped at a salt mine in Hungary her father had given her.

She supposedly threw her engagement ring inside as a sign of ownership. She then headed

to Poland with a group of Hungarian miners in tow. And when she approached the

Wieliczka region, she told the miners to dig into the ground. They did. Their reward was a

treasure — an enormous bounty of crystalline salt. Hidden in the salt was Kinga’s ring.

Although charming, that’s clearly a tall tale.

The real story of Wieliczka’s salt began millions of years ago, says Krzysztof Bukowski

[BOO-koov-skee]. He is a geologist at AGH University of Science and Technology in Kraków.

His group studied the mine’s salt crystals to figure out where all that salt came from. The

team determined that the region had once been connected to the salty ocean.

Over time, that seawater evaporated, leaving behind salt. Lots and lots of it.

That conclusion is based on inclusions in the rock salt.

In geology, an inclusion is a bit of something inside a rock. It had to exist before the rock

formed. Bukowski explains, it’s “like a time capsule.” At the mine, some inclusions are bits

of ancient water. That water, in turn, contains ions. Those are charged atoms or molecules.

Bukowski’s group looked at the levels of potassium, magnesium and sulfate ions in samples

from the crystals. They were similar to their levels in modern seawater. And the results

were unlike those for inland salt lakes (such as Utah’s Great Salt Lake).

That’s not all. Some inclusions contained the remains of one-celled organisms. In one study,

Bukowski’s group looked at the different species of a group called foraminifera [Foh-ram-

uh-NIF-er-uh]. The relative amounts of different species provided clues about the

temperature and available food in that sea long ago.

Wieliczka’s mineral wealth is halite (HAY-lyte). You know it as sodium chloride, or common

table salt. Starting in the 13th century, this resource brought prosperity to southern

Poland. (Indeed, the term “salary” comes from the Latin for salt. History suggests some of

the ancients may have been paid for their labors in salt. That led to the phrase “worth his

salt.”)

The air down there

Decades ago, some of the mine’s famous statues began dissolving. The staff called in

scientists to investigate how to stop the loss of these treasures. But first the researchers

had to better understand the mineral structure of the site’s salt. They also had to focus on

controlling moisture.

By the 1990s, air pollution was causing details to

dissolve on some of the mine’s statues closest to mine’s

entrance. Scientists developed a system to lower

humidity inside the mine, which halted most further

damage.

K.M. Kowalski

Relative humidity is a measure of how moist the air is.

Pure rock salt stays solid as long as the relative

humidity is below 75 percent. But pollution can make

salt more vulnerable to melting.

Air enters the Wieliczka mine from above the ground.

Since the 20th century, it has come in tainted with

modern pollutants. These include sulfur dioxide and

chemicals produced by burning fossil fuels. Once inside the mine, these pollutants stick to

the salt and anything carved from it, including the statues.

This changed the surface chemistry of the salts, especially of the salt closest to the entrance.

No longer pure sodium chloride, the salt now could dissolve at lower humidity levels. And

that’s important because humidity levels in the mine had grown high. A primary source?

The breaths of tourists visiting the mine.

Each exhaled breath sent moisture into the air. It collected on the salt, forming a fine liquid

film. That film was dissolving some of the carvings’ fine features. A face would lose its nose

and ears. Or a hand might lose its fingers as they slowly dripped away.

When scientists recognized the role of pollution and breaths, they installed a system to

lower the level of water vapor in its air. The system worked! Wieliczka came off the list of

endangered UNESCO sites 19 years ago.

Still, that didn’t erase threats to the mine.

The ruin of rust

Many of this mine’s deposits naturally formed into fanciful shapes. Known as speleothems

(SPEE-lee-oh-thems), they might look like icicles, soda straws, popcorn or even lacy crusts.

These form as water loaded with minerals seeps into a cave. As the moisture evaporates,

the minerals stay behind.

“There are fantastic structures that you cannot find anywhere [else],” says Jerzy Przybyło

[PZHIH-bih-woh]. He’s a geologist at the Wieliczka mine. Unlike speleothems in many other

caves, those at Wieliczka are solely salt. But owing to impurities, the salt here can be

yellow, red — even brown. Pure salt would appear clear or milky white.

Przybyło works with geologists at Jagiellonian University in Kraków. They probed some of

the mine’s salt rocks under high magnification. Uneven surface features emerged. The

group also dissolved bits of different-colored speleothems in water. Then they compared

these to samples of brine from the mine. (Brine is water with a lot of dissolved salt.)

Along with the salt’s sodium and chloride they turned up iron and more.

Many of the iron-based compounds seem to exist only on the salt’s surface. This appears to

reflect rust deposited from mining tools. Over hundreds of years, tools would have broken

or chipped in the mine. The salty environment would have sped up their corrosion, the

researchers believe. They described their findings three years ago in Geological Quarterly.

Rust added pretty colors to the mine’s salt formations. But those corroding tools might now

be damaging some of the mine’s wooden structures.

Many of the wall and roof supports are wood, as are the stairs. Workers also used some

wooden tools. For instance, a huge wooden machine once hoisted heavy rock salt up to the

surface. A team of chemists from Poland and Italy examined wooden objects in the salt

mine’s museum. And the spruce, pine and fir samples they studied definitely were

deteriorating.

Salt had combined with iron oxides from tools to make compounds that entered the wood.

Those compounds sped up the decay process, the team concluded. Their findings might

now help people figure out better ways to preserve wooden items.

Mother Nature doesn’t help

Wooden timbers and more modern supports

help shore up the mine. But the walls and

ceilings are still salt. And too much water could

cause cave-ins.

The Carpathian Mountains extend for 1,500

kilometers (930 miles) through Central and

Eastern Europe. Movements of Earth’s tectonic

plates push those mountains up, explains

Krzysztof Brudnik [BROOD-neek]. He’s a

geologist at the Wieliczka mine. “The salt deposit

is on the border of the Carpathians,” he notes. Those tectonic movements can push more

groundwater towards the mine.

Impurities such as iron compounds can give salt crystals different hues.

K.M. Kowalski

Mining also affects water flows. Over the years, miners have poked holes through different

rock layers, Brudnik and his colleagues have found.

Today, about 140,000 cubic meters (37 million gallons) of groundwater enter the mine

each year. That’s enough water to fill nearly half a million bathtubs! In contrast, only about

7.2 liters (2 gallons) enter the Bochnia salt mine fewer than 30 kilometers (19 miles) away.

Water entering the mine now gets pumped to the surface. Brine flows down wooden ramps

in a wide tower outside the mine. That creates a salty aerosol for spa visitors to enjoy. Salt

also is extracted from this liquid to make kitchen salt, bath salts and other products.

One bad flood in 1992 “was a threat not only to the mine, but also for the town,” Brudnik

says. Officials posted plans around town just in case a large cave-in occurred. People would

have needed to suddenly evacuate.

Fortunately, that didn’t happen. Water came in, but the whole mine wasn’t flooded. Still, it

took about eight months to stop the flow.

Effects of the flood remain. Zbigniew Perski [PEHR-skee] is a geologist at the Polish

Geological Institute in Warsaw. He and his colleagues found signs of some small cave-ins

when they used satellite data to study land around the town. Their work also showed the

results of some above-ground landslides in the area.

The nearby mountains may have played a role in some of those events, too, the team

suggests.

A breath of fresher air?

Another recent study looked at the mine’s levels of particle pollution, or PM. High levels of

super small airborne particles can worsen asthma and other respiratory diseases.

Breathing these tiny particles also has been linked to a heightened risk of heart disease. But

the mine’s salty surfaces may act like a sponge to remove many of these particles from the

air, researchers now report.

Magdalena Kostrzon [KOHST-zhohn] is a biologist who works at the mine’s spa and health

resort. She and a team of environmental engineers found lower levels of PM in the spa’s

underground treatment rooms than in various outdoor areas of Poland.

Before entering the spa’s rooms, incoming air must pass through 700 to 800 meters (765 to

875 yards) of salt tunnels. Many tiny particles of pollution stick to the tunnel walls.

Moisture turns some of the surface salt into ions — electrically charged molecules. Those

small electric charges appear to grab and hold onto the airborne particles.

People living in Kraków and other cities with lots of outdoor air pollution would like to

spend time somewhere with cleaner air, Kostrzon says. “You can find such a place,” she

says, “135 meters [150 yards] below the ground in the Wieliczka Salt Mine.” Her team

reported its findings last year in the book Pathobiology of Pulmonary Disorders.

Visitors continue to flock to Wieliczka. One recent project laid tracks for an underground

train. It will soon open to let visitors see more parts of the mine.

Meanwhile, Brudnik and his team still keep an eye on the flow of water into the mine. He

and Przybyło also have been overseeing work to fill in some of the mine’s rooms with sand.

That can cut the risk of their collapsing as Earth’s natural forces continue to push up the

nearby mountains. (Think about how it takes more force to push down a solid block

structure than a hollow one.)

As part of that work, the geologists look for any unusual salt formations in places that

might need to be filled in. Their team wants to save those formations, where possible. But

in any case, “the safety of the mine [and] the safety of people is the priority,” Brudnik

stresses.

“It is remarkable to think what this particular mine has survived, and what its generations

of workers have experienced,” says Isabelle Anatole-Gabriel. She’s a historian and

archaeologist at UNESCO’s World Heritage Centre in Paris, France. During the mine’s long

history, Poland has been a kingdom. Then the country was split up and disappeared. Later

its territories rejoined. Just 65 years ago, Nazis invaded Poland. After World War II,

communists took over. The country is a democracy now, but it faces new challenges.

Throughout all of this, the Wieliczka mine has been part of Poland’s culture. It shows the

“evolving interconnection between humankind and the Earth,” Anatole-Gabriel says.

UNESCO’s World Heritage Committee lists Wieliczka as one of its “success stories.”

How so? Using science, the mine’s staff has halted the rapid melting of its structures and

charted a path to saving them.

Protecting world heritage sites often, as here, requires cooperation from people in a range

of nations. But their success means people can have a chance to enjoy such sites for

centuries to come.