Norwegian explorer Roald Amundsen became the first man to reach the South Pole in December 1911. More than 100 years later, an international team of scientists that includes a NASA researcher has proven that air pollution from industrial activities arrived to the planet’s southern pole long before any human.
[image-51]Using data from 16 ice cores collected from widely spaced locations around the Antarctic continent, including the South Pole, a group led by Joe McConnell of the Desert Research Institute (DRI) in Reno, Nevada, created the most accurate and precise reconstruction to date of lead pollution over Earth’s southernmost continent. The new record, described in an article published today in the online edition of the Nature Publishing Group’s journal Scientific Reports, spans a 410-year period from 1600 to 2010.
"Our new record shows the dramatic impact of industrial activities such as smelting, mining and fossil fuel burning on even the most remote parts of the world," McConnell said.
"It is very clear that industrial lead contamination was pervasive throughout Antarctica by the late 19th century, more than two decades before the first explorers made it to the South Pole," he added. "The idea that Amundsen and Scott were traveling over snow that clearly was contaminated by lead from smelting and mining in Australia, and that lead pollution at that time was nearly as high as any time ever since, is surprising to say the least."
This study included ice cores collected as part of projects funded by the National Science Foundation. Additional ice cores were contributed to the study by international collaborators including the British Antarctic Survey, the Australian Antarctic Division and the Alfred Wegener Institute in Germany.
"The ice cores obtained through international collaborations were critical to the success of this study in that they allowed us to develop records from parts of Antarctica not often visited by U.S.-based scientists," said co-author Tom Neumann of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, who participated in a Norway-U.S. traverse that collected several of the cores used in this study. "This included the Law Dome region of East Antarctica and a big section of East Antarctica visited by the Norwegian-United States Scientific Traverse of East Antarctica."
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All measurements of lead and other chemicals used in this study were made using DRI’s continuous ice core analytical system. Low background atmospheric concentrations, together with well-known and often distinct isotopic characteristics (variants of lead with different atomic weights) of industrial sources make lead an ideal tracer of industrial pollution.
"Lead is a toxic heavy metal with strong potential to harm ecosystems," said co-author Paul Vallelonga of the University of Copenhagen. "While concentrations measured in Antarctic ice cores are very low, the records show that atmospheric concentrations and deposition rates increased approximately six-fold in the late 1880s, coincident with the start of mining at Broken Hill in southern Australia and smelting at nearby Port Pirie."
[image-78]The similar timing and magnitude of changes in lead deposition across Antarctica, as well as the characteristic isotopic signature of Broken Hill lead found throughout the continent, suggest that this single emission source in southern Australia was responsible for the introduction of lead pollution into Antarctica at the end of the 19th century and remains a significant source today, the authors report.
Data from the new ice core array illustrates that Antarctic lead concentrations reached a peak in 1900 and remained high until the late 1920s, with brief declines during the Great Depression and the end of World War II. Concentrations then increased rapidly until 1975 and remained elevated until the 1990s.
Concentrations across the Antarctic continent have since declined, but still are about four-fold higher than before industrialization, despite the phase out of leaded gasoline and other mitigation efforts in many countries in the Southern Hemisphere, the report states.
"Our measurements indicate that approximately 660 tonnes [1.5 million pounds] of industrial lead have been deposited on the snow-covered surface of Antarctic during the past 130 years," McConnell said. "While recent contamination levels are lower, clearly detectable industrial contamination of the Antarctic continent persists today, so we still have a ways to go."
File photo of the Antarctic, 2006.  

Researchers from , , , , , and the  conducted  concentration measurements of sixteen  samples, and found that industrial  has persisted  since its arrival there in 1889 and remains significant in the current century. Their study was published in '''' on July 28, and covered in 's '''' this Saturday.

Lead was chosen to trace the industrial pollution of atmosphere because of its low natural concentrations in , as well as unique '' of different sources. Each lead  deposit has its own distinct mixture of . Analysis of such characteristic isotopic signatures traced , Australia as the pioneering source of lead pollution in Antarctica, and even today its contribution remains significant. Coauthor Paul Vallelonga detailed, "Lead is a toxic  with strong potential to harm ecosystems ... While concentrations measured in Antarctic ice cores are very low, the records show that atmospheric concentrations and  rates increased approximately six-fold in the late 1880s, coincident with the start of mining at Broken Hill in southern Australia and smelting at nearby ".  Lead author Joe McConnell noted, in '''', "A single industrial complex was enough to contaminate the entire continent of Antarctica thousands of kilometers away ... We're still polluting Antarctica today".

McConnell said in getting the cores he traveled to Antarctica "four or five" times. Each of the drilled samples is about 4  (10 ) across and 100–500  (30–150 ) long. They were cut for storage in boxes, six three-foot sections per box weighing over 100  (450 ). A single ice core can be used by researchers in many experiments during the next several years.

Concentrations of lead on the Antarctic continent have declined after the 1990s, but remain around three times higher than before industrialization, despite  and similar . As McConnell said, "Our measurements indicate that approximately 660 tonnes 1.5 million pounds of industrial lead have been deposited on the snow-covered surface of Antarctic during the past 130 years ... While recent contamination levels are lower, clearly detectable industrial contamination of the Antarctic continent persists today, so we still have a ways to go."

Support for the study came from, amongst others, the U.S. , WAIS Divide Science Coordination Office, Ice Drilling and Design and Operations, the , , and the  .


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