The first lead pollution in Antarctica occurred as a result of industrial emissions more than 20 years before explorers reached the South Pole, scientists have discovered.
Norwegian Roald Amundsen became the first man to set foot on the pole in December 1911 - followed a month later by Britain's Captain Robert Scott - but the international team have proven that pollution from industrial activities in southern Australia arrived at the end of the 19th century.
Data from 16 ice cores collected from all over the frozen continent show that lead concentrations reached a peak in 1900 and remained high until the late 1920s, with brief declines during the 1930s and 40s when the Great Depression and Second World War were going on.
Concentrations then increased rapidly until 1975 and remained elevated until the 1990s.
Dr Joe McConnell, the study's lead author, said: "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.
"The idea that Amundsen and Scott were travelling 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."
Although recent contamination levels are lower, the Antarctic is still being polluted today despite the phasing out of leaded petrol and other mitigation efforts in many countries in the Southern Hemisphere, the report states.
While the concentrations measured in the Antarctic ice cores were very low, the data shows that atmospheric concentrations and deposition rates increased approximately six-fold in the late 1880s, coinciding with the start of mining at Broken Hill in the New South Wales outback.
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 report said.
Dr McConnell, who is based at the Desert Research Institute (DRI) in Reno, Nevada, in the United States, said the team had to work in extreme conditions to gather their evidence, at one stage working in temperatures of as low as -77C..
The lead and other chemicals were measured using the DRI's continuous ice core analytical system and included ice cores collected as part of projects funded by the US National Science Foundation.
Additional ice cores were provided by international collaborators including the British Antarctic Survey, the Australian Antarctic Division, and the Alfred Wegener Institute in Germany.
The study, which is published today in the online edition of Scientific Reports, spans a 410-year period from 1600 to 2010.
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