Geotimes Logo NEWS NOTES  March 1999 

by Kristina Bartlett and Devra Wexler
 
 Sunken ship (Blackbeard's?) aids science
 Yucca Mountain still a go
 Russia's troubled waters
 Earth Science Week '99 kicks off
 Stalagmites reveal past climate
 

Sunken ship (Blackbeard's?) aids science

The Queen Anne's Revenge, once the flagship of the pirate Blackbeard, ran aground in Beaufort Inlet, N.C., in June 1718. For nearly three centuries, the vessel remained buried in the shifting sands off the Carolina coast. But in November 1996, Intersal Inc., a private research firm, discovered a shipwreck that could be the 280-year-old remnant of Blackbeard's prized ship.

In cooperation with the N.C. Division of Archives and History, Intersal formed the Maritime Research Institute (MRI) to work on the Queen Anne's Revenge (QAR) project. In addition, a number of geoscientists from local universities have signed on to help.

"We got involved with this project at the request of the state's underwater archaeology unit," says Dr. John T. Wells, geology professor and director of the Institute of Marine Sciences (IMS) of the University of North Carolina at Chapel Hill (UNC-CH). "[We were asked] to see if techniques we use could be brought to bear on unraveling some of the environmental science and physical science aspects of the wreck site. We felt that being able to offer some expertise the unit didn't already have was a great opportunity for us and for the state, especially since the wreck is practically right at the institute's back door."

Wells has been digitizing old maps and marine charts, dating to the early 1700s, of the wreck site and the surrounding area to compare with modern charts and conditions. One goal is to create a history of physical changes that occurred over time, by studying the inlet's shifting sands and comparing the movement to past disturbances. The inlet has also sustained a rise in sea level of perhaps three feet. Preliminary information, Wells says, shows that the orientation of Beaufort Inlet has "flopped around tremendously" in the past 300 years. Wells works with Christopher Martens, UNC-CH marine science professor, and Neils Lindquist, associate professor at IMS.

"We are trying not only to understand what happened to the sea and the shore in the area, but also to see the frequency of change, what hurricanes did, how sand shoals moved, ... and how Beaufort Inlet naturally realigned itself over time," Wells says. The scientists deployed an electromagnetic current meter and wave sensor at the site in May 1998, which is providing details of storms, waves, and tides that have acted on the wreck.

Because most of the ship has been buried under sand since it went down, it is quite well preserved. The bottom of the hull is still intact. Nearly 20 cannons have been found, as well as cannonballs, anchors, and the anchor stocks.

Numerous artifacts have also been found. The project archaeologists have been tracing the history of a bell, dating to 1709, found among the cannons and wood planks and are puzzling over the discovery of a number of old syringes. (These probably come from medical supplies that Blackbeard is known to have stolen for his crew.) Not all of the artifacts, however, date to Blackbeard's time. Divers have found well-preserved wine bottles at the wreck site, at least one of which, the scientists believe, is from the Civil War era.

Studying the corals and encrusting organisms such as barnacles and sea whips that have latched onto the recovered artifacts, Lindquist hopes to determine which parts of the wreck have been periodically exposed - and when - as waves and tides moved sediments around and over it.

In mid-October, for example, shortly before the site was closed for the season, he and other IMS geologists took sediment samples from beneath several large ballast stones. "Each stone was smooth on top and had an old growth of barnacles on its underside, indicating that some time after the shipwreck the ballast were rolled over and then covered with sand. This most likely occurred soon after the ship wrecked," the project manager wrote in that day's dive report.

The ballast stones are useful for analyzing any movement of the wreck in recent times as well. Nuclear testing in the 1950s released radioisotopes such as cesium-137 and plutonium-239 and -240, which have accumulated in most marine sediments worldwide. By analyzing the sediments cored from beneath the ship's hull and ballast stones, Martens should be able to detect any later wreck movement. "We won't find the bomb-produced radioisotopes directly under the hull or stones unless they moved due to storms or other events," Martens explains. "That should tell us something about the impact of storms."

Using radiocarbon dating techniques, Martens also studies wood samples from the hull and anchor stocks, brought up last October, and other organic material such as the horsehair that was forced into cracks between planks to seal the hull. "Since the ship sank in the early 1700s, we expect the oldest wood to be between 300 and 400 years old," he says. He adds that he is using the accelerator mass spectrometer facility at the Woods Hole Oceanographic Institution (WHOI) to date the samples because of its extreme accuracy.

At press time, Wells reported that the researchers expect to receive exciting new data back from WHOI soon. The scientists will return to the wreck site next fall.

 - D.W.
 


Yucca Mountain still a go

This newsnote has been revised, removing a reference to a lawsuit, to reflect an erratum appearing in the May 1999 issue of Geotimes.

For the past 15 years, scientists working for the Department of Energy (DOE) have been conducting tests at Yucca Mountain in Nevada to determine if the site would be suitable for a high-level nuclear waste repository. Despite numerous challenges and delays, the department cleared another hurdle last December with the release of an interim report, Viability Assessment of a Repository at Yucca Mountain, that gave managers a green light to continue work on the project. Research on the site's suitability will move forward until a final decision is made two years from now.

The search for a repository began in 1982 when Congress passed the Nuclear Waste Policy Act (NWPA), which instructed DOE to develop a permanent storage site in a deep geologic formation for spent nuclear fuel and high-level radioactive waste produced by industry and government. In 1987, Congress amended the act to make Yucca Mountain, located approximately 100 miles northwest of Las Vegas and adjacent to the Nevada Test Site, the sole site for continued study. The repository was mandated to open in 1998, but delays in the site-characterization process have pushed that date back to 2010. Increasingly frustrated by the delays, Congress in 1997 directed DOE to prepare a report ("viability assessment") that would provide the president, Congress, and the public with information on the progress of research at Yucca Mountain.

Viability Assessment
The report released in December explains and assesses the current design concept and provides a cost estimate for the operation of the facility. Under the current design, nuclear waste would be transported to Yucca Mountain by specially licensed trains and trucks, beginning in 2010. The waste would be inspected, placed in containers suitable for long-term storage, sealed, and moved into the repository, which would be located at least 200 meters below the surface and 100 meters above the groundwater table. The waste would be stored and monitored for 100 years, at which point the facility would be closed and sealed. Although the storage containers would eventually dissolve, the volcanic tuff would act as a natural barrier to waste migration. The position of the repository well above the water table is another critical design feature for isolating the waste.

To complete the Viability Assessment, scientists used information gathered from tests conducted at Yucca Mountain to create models to analyze this design. They found that the most critical factor affecting public health and safety is the amount of water that comes in contact with the waste. Although uncertainties remain, the assessment found that little or no increase in radiation exposure would occur for people living near Yucca Mountain for 10,000 years. Commenting on these results, Secretary of Energy Bill Richardson stated, "Before the site can be recommended, DOE will need to demonstrate that a repository can be designed and built at Yucca Mountain that would protect the health and safety of the public and the environment for thousands of years." He announced that DOE will continue to conduct tests at Yucca Mountain to address uncertainties as to how the design, natural processes, and the site will work together. The assessment estimated total future costs for licensing, construction, operation, monitoring, waste transport, and other expenses associated with the life of the facility (1999-2116) to be $36.6 billion dollars.

Opposing Views
Although the new report is good news for the Department of Energy and Yucca Mountain supporters, it does not put an end to the controversy surrounding the site. Several scientists have recently raised new concerns about the suitability of the site. In January, scientists from Lawrence Livermore and Los Alamos National Laboratories published a paper in Nature that found plutonium in groundwater near Yucca Mountain, almost a mile from the site of an underground blast. Scientists believe that this finding indicates that particles can move through groundwater much faster than previously believed. Lead researcher Annie Kersting said, "I think Yucca Mountain [planners] should be concerned with these results." In addition, geoscientist Yuri Dublyanski of the Russian Academy of Sciences and former DOE scientist Jerry Szymanski have argued that flooding has occurred in the mountain by hot water upwelling during the past 12.5 million years. During a visit to Yucca Mountain, Secretary Richardson stated, "These are issues that deserve a thorough examination. I am very intent on making my decision based on science, not politics."

- Kasey Shewey White, AGI Government
Affairs Program


Russia's troubled waters

The Western Siberian Artesian Basin, which occupies about 3.5 million square kilometers in Russia, is the largest area of low relief on Earth. Three former nuclear production sites probably make it the most radioactive area on Earth, too. Particularly notorious is Mayak, a former plutonium production site about 80 kilometers north of the city of Chelyabinsk (population 1 million) along the southern Ural Mountains. Surficial radioactive contamination in the region reaches over 100 million Curies (Ci).

As part of a 1990 agreement between Russia's MINATOM (Ministry of Atomic Energy) and the U.S. Department of Energy (DOE), scientists with the Pacific Northwest National Laboratory (PNNL) in Richland, Wash., are designing computer models that will help the Russian scientists predict the paths that radioactive materials will take through the region's groundwater system. PNNL also models contaminant transport for Richland's Hanford site, one of the largest nuclear cleanup sites in the United States.

The modeling project uses data supplied by Russian scientists, who have been monitoring the contaminant movement from Mayak and its effects on health since the early 1950s. "This is really the only example of such extensive contamination that has been monitored over a long period of time," says Mike Foley, a geologist with PNNL. "This research is the best chance to learn how large concentrations of man-made radionuclides travel in a natural setting, over long distances, and over a long period of time." The models will help the researchers understand how radioactive wastes react with rocks as they are transported by groundwater.

The Techa River
Plutonium was produced for nuclear weapons at Mayak, starting in 1949. At that time, Russian scientists discharged the radioactive waste directly into the Techa River. The DOE helped fund a 1995 study of the area, conducted for the International Institute for Applied Systems Analysis (IIASA) in Austria by Russian, American, Finnish, and Austrian scientists. They calculated that about 76 million cubic meters of waste, with a total radioactivity of 2.86 million Curies, were released into the Techa River between 1949 and 1956. The waste carried strontium-90, which accumulates in bones, and cesium-137, which passes through the metabolic system, to the approximately 28,000 people living along the river. Production of plutonium at Mayak continued until 1990, and the site is still used to reprocess fuel from nuclear reactors and to produce special isotopes, the researchers wrote in the January/February 1997 issue of Environment magazine. "Although current operations are on a much lower scale, contamination problems remain."

Mayak officials constructed reservoirs and bypass channels along the Techa to minimize its contamination. Foley says these reservoirs and channels still leak contaminated water into the groundwater system. The largest reservoir, formed by a dam, covers 44 square kilometers and contains almost 230 million cubic meters of water. The failure of this dam could render the entire Techa valley uninhabitable for at least three years, the IIASA team wrote. The river eventually drains into the Arctic Ocean, although most of the radionuclides collect in river sediments along the way.

Modeling a Radioactive Plume
It took only a few years for the polluted river's adverse effects (especially on human health) to be noticed, and in 1951, Mayak officials started discharging the waste into Lake Karachay instead. Today, the lake contains about 120 million Ci of radioactive material (by comparison, the Chernobyl accident released about 50 million Curies). "It is probably the largest open accumulation of nuclear wastes in the world," the IIASA team wrote.

Russian scientists raised the lake's nitrate content to force lake water seeping into the groundwater to sink. As a result, a radioactive nitrate brine has spread north and south from the lake, primarily along the interface between surficial sediments and underlying fractured basement rocks. The plume alone contains more radioactive material than was released to the ground on the PNNL's entire Hanford site. About two kilometers south of the lake, the tip of the plume, which Foley estimates is 1,000 meters wide, 4,000 meters long, and 100 meters thick, has reached the Mishelyak River, which flows into the Techa River, which in turn flows into the Iset' River, the Tobol River, the Irtysh River, and finally to the Ob River. The Ob empties into the Kara Sea and thence to the Arctic Ocean. Russian scientists have already detected strontium-90 in wells near the Mishelyak, Foley says. Most of the radioactive materials, which have 30-year half-lives and would decay a million-fold in about 600 years, could decay for the most part before reaching the Arctic, Foley adds.

Foley's team has created a model of the Western Siberian Artesian Basin's groundwater system and a detailed model of the groundwater system around Mayak. Their next step, he says, is to model the motion of the radioactive plume from Lake Karachay. To test the model, they will predict the plume's motion over the past 50 years and compare that prediction with the motion observed by Russian scientists over the same time period. The model will help Russian scientists test possible ways to stop the plume's progress into the surface-water system. For example, Foley says, a wall of frozen water could dam the plume - but would it also cause the plume to spread upward into the surface water of surrounding farms? "What you really have to watch out for is that you don't do something that makes it worse," Foley says. "If you're going to change something about a hydrological system, you want to be sure you're making a change for the good."

The plume gives the PNNL researchers what no laboratory experiment could offer. "It is showing us a very large contaminated plume that has moved thousands of meters over decades and has been studied since that time," Foley says. "We need to know the chemistry of how radioactive plumes move below the surface ... We have to be able to predict the risk of contaminant migration in order to properly clean it up."

Tomsk and Krasnoyarsk
The PNNL researchers will eventually model the groundwater movement from two other contaminated sites (Tomsk and Krasnoyarsk) in the basin, which holds several large oil fields. Russian scientists have been storing billions of Ci of radioactive contaminants by injecting them deep underground into aquifers like those that isolate the oil. Foley says the area's five-layer artesian system offers confining layers and aquifers that isolate and buffer these radioactive wastes. Studies by the Russian scientists who selected and tested these sites indicate that the water moves slowly and is isolated from fresh water lying above the aquifers. Most likely, Foley says, the groundwater is moving slowly enough to provide the 1,000-year containment necessary for their radioactivity to decay to negligible levels. PNNL researchers hope to work with the Russian scientists and develop models for predicting the movement of the contaminants in these areas.

- K.B.


Earth Science Week '99 kicks off

 
 The fact that more than 15,000 teachers and scientists asked for information about Earth Science Week prior to its occurrence last October should have prepared the staff at the American Geological Institute (AGI) for the enthusiastic response they would receive after the event. Encouraging letters poured in, many from elementary school classrooms. Philip LaMoreaux, former state geologist of Alabama, sent in letters he received from Tuscaloosa schoolchildren. One girl wrote, "Dear Dr. Phil... Thank you very much for letting me come and see all the neat things you have. ... I like how you told us about the little white pebbles you could find where the earth mounds came and made together." Perhaps most rewarding was the letter from young Hunter Cole. "Dear Dr. LaMoreaux," he wrote. "There are two things I want to be when I grow up, a geologist and president. But mostly geologist."

Program planning for this year's Earth Science Week is already underway. A number of schools, museums, companies, and geological surveys will be conducting workshops and organizing planning committees in the coming months. Julie Jackson, Earth Science Week program director, says, "It's great to see people getting a head start for Earth Science Week 1999. It is especially encouraging to have participation from so many different types of organizations."

Planning activities start this month. On March 18, AGI and the U.S. Geological Survey (USGS) are jointly hosting a kick-off meeting and preparation workshop for Earth Science Week '99. AGI Executive Director Marcus Milling says that invitations are being extended to all state geologists and to representatives of AGI member societies and federal agencies. "We're hoping for a diverse group of participants to broaden the scope and impact of Earth Science Week in 1999," he says. Attendees at the March 18 workshop will also review overall outreach programs for the earth sciences.

The state geological survey in Arizona is forming committees to work on programs throughout the state. The Illinois State Geological Survey (ISGS) is incorporating Earth Science Week information for an upcoming meeting. At the end of April, the ISGS is hosting the North-Central section of the Geological Society of America meeting, and they have asked Julie Jackson to speak about Earth Science Week.

The Ohio State University Extension in Marietta, Ohio, is hosting teacher workshops to prepare for Earth Day on April 22. They will use some Earth Science Week '99 materials in their workshops, since this year's Earth Day will focus on the physical aspects of Earth in addition to environmental concerns.

Phillips Petroleum sponsors "Energy Days" in April for the Green Country Elementary Schools in Oklahoma. Approximately 1,000 fifth-graders and 50 teachers will participate in activities that explore the importance of petroleum and its products. Games and experiments will illustrate how oil is discovered and processed, where it can be found, and how it affects people's everyday lives. Students will learn how to respond to environmental emergencies and will see how the petroleum industry has changed through its history. Because of the success of the Earth Science Week programs last fall, Phillips has asked AGI to contribute posters and teaching aids to the "Energy Days" activities.

On April 10, The Girl Scout Council of the Nation's Capital hosts the annual Girl Scout Day at the National Air and Space Museum in Washington, D.C. The council invited AGI to run a hands-on display or activity at their event, to provide the scouts with a first-hand earth-science experience. Karen Brown, the program specialist, wrote to Jackson, "One of the goals of [the council] is to strengthen girls' interest in science. ... By offering opportunities to learn in a noncompetitive environment, we hope to spark an interest that will continue through junior and senior high school and into college. Girl Scout Day ... offers many 'hands-on' activities and provides the girls the opportunity to share in the fun and excitement of math and science-related fields with scientists who love their work."

Earth Science Week is scheduled for Oct. 10-16, 1999. For more information go to: http://www.earthsciweek.org or contact AGI at: (703) 379-7563 (fax).

 - D.W.


Stalagmites reveal past climate

Stalagmites from a Missouri cave have yielded a clear picture of climate and vegetation change in the midcontinental region of the United States during the millennia leading up to the last ice age (75,000 to 25,000 years ago) - until now, a period for which such data have been scarce. The records show that average temperature fluctuations of 4 degrees Celsius were associated with significant changes in vegetation, including a sharp shift from a prairie ecosystem to forest 55,000 years ago, when temperatures fell and ice sheets began to grow. A study published in the Dec. 4, 1998, issue of Science reveals the value of the stalagmites in reconstructing past climate.

"It hasn't been clear how climate and vegetation changed between 120,000 years ago - when conditions were similar to today's - and 20,000 years ago, when the last ice age was at its peak," says Jeffrey Dorale, lead author of the Science paper and a geology graduate student at the University of Minnesota. "Much of the data come from the oceans, and while that's good in determining global patterns, it's less helpful [for] figuring out local and regional climate histories." Climatic change in continental regions is most frequently studied by examining pollen in lake sediments, he adds. But most lakes in the mid-United States are younger than 15,000 years, and the few older deposits that do exist are difficult to date. Cave formations, however, can be much older, and may be amenable to precise and accurate dating.

Stalactites and stalagmites, well-known limestone structures to cave enthusiasts, are layered, similar to rings in a tree. Stalagmites usually have sharper, more easily studied rings than the icicle-like stalactites.

"Techniques developed in the last decade by Larry Edwards and others at the University of Minnesota have made possible this kind of resolution in dating calcium carbonate minerals such as stalagmites and corals," says Dorale. The dating techniques are based on the radioactive decay of uranium and allow scientists to determine the ages of material much older than what can be determined by using carbon-14 dating. Edwards, a professor of geology and geophysics at the university, is a co-author of the paper. Dorale and Edwards were joined in their research by Minnesota geology professor Emi Ito and Luis González of the University of Iowa.

The researchers examined four stalagmites from Crevice Cave, the longest cave known in Missouri, located about 75 miles south of St. Louis. The stalagmites appeared to have been broken by natural forces such as floods or earthquakes and were found about 80 feet below the ground surface, says Dorale. The team determined when the stalagmite layers were deposited, then deduced paleotemperatures and the general types of vegetation growing in the vicinity during that era by examining the carbon and oxygen isotopes within the calcium carbonate.

In addition to revealing the temperature at the time of deposition, the isotopes also indicate plant type - whether the area held warm-season grasses or cold-season grasses and trees - allowing Dorale and his co-workers to construct a temperature-vegetation profile of the area. It became evident that in the midcontinental region, even moderate temperature shifts could affect the form of vegetation, which is sensitive to the temperature-moisture balance.

"Shifts of a few degrees can really push systems over the threshold to forest or grassland," says Dorale. The profile showed that the area had been covered by forest 75,000 years ago, but by 71,000 years ago, it was savannah and by 59,000 years ago, had become a prairie. Between 55,000 and 25,000 years ago, the forest had returned and persisted. Dorale explains that the pattern is consistent with climatological records from the ocean.

Dorale says that further study is needed to determine how wide a geographic area is represented by the climatic history uncovered in Crevice Cave. "We think this research should continue. Caves should not be overlooked as a resource in climatological studies."

- D.W.


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