|Roald Amundsen/ public domain|
"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," said Joe McConnell of the Desert Research Institute (DRI) in Reno, Nevada.
Using data from 16 ice cores collected from widely spaced locations around the Antarctic continent, including the South Pole, a group led by McConnell, created the most accurate and precise reconstruction to date of lead pollution over Earth’s southernmost continent.
"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."
"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."
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.
"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."
The report is published in the online edition of the Nature Publishing Group’s journal Scientific Reports.
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