Cape Town - We all know that Robert Falcon Scott and his four British companions struggled through the vast pristine spaces of icy Antarctica, only to find that Roald Amundsen’s Norwegian party had beaten them to the South Pole, right?
Well, yes and no. Amundsen and his men may well have been the first people to stand at the southern-most point of the world but one of the scourges of the modern industrial world had arrived at least two decades earlier: lead pollution.
More than 100 years after the Norwegians raised their flag at the pole on December 14, 1911, research by an international team of scientists led by Dr Joe McConnell of the Desert Research Institute in Nevada, US, has shown that industrial activities were polluting the pure Antarctic air well before their arrival.
The likely source of this particular pollution was the massive lead mine that started at Broken Hill, southern Australia, in the 1880s and the associated smelting at nearby Port Pirie.
McConnell’s team used data from 16 ice cores collected from around the Antarctic continent – including the South Pole – to create what they describe as “the most accurate and precise reconstruction to date of lead pollution over the Earth’s southern-most continent”.
Their new record, described in the online edition of the Nature journal Scientific Reports, spans a 410-year period from 1600 to 2010 AD.
It “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 McConnell, a research professor and director of the Desert Research Institute’s ultra-trace ice core analytical laboratory.
“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.
“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.”
Co-author Paul Vallelonga, an associate professor at the University of Copenhagen, said lead was a toxic heavy metal with strong potential to harm ecosystems.
“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.”
Data from the new ice core array shows that lead concentrations are still about four times higher than before industrialisation, despite the phasing out of leaded petrol and other mitigation efforts in many countries in the southern hemisphere, their report states.
“Our measurements indicate that approximately 660 tons 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 to- day, so we still have a ways to go.”
He explained some of the hazards of working in such extreme environments: “I remember the day in 1999 we drilled the shallow core about 15km from South Pole. The temperature was negative 100 degrees Fahrenheit (–73oC) with the wind chill, so it was hard to motivate the field team to leave the galley at the South Pole station that day.”
The lowest natural temperature directly recorded at ground level on Earth is –89.2°C, at Russia’s Vostok Station in the eastern highlands of Antarctica in 1983.
However, scientists have since announced they used new satellite data to measure an even lower temperature in the same region: –93°C.
Although the new record was revealed only in December last year, it was set on August 10, 2010.
Researchers used 31 years of data from advanced high-resolution radiometer instruments on US National Oceanic and Atmospheric Administration satellites, instruments on Nasa’s Terra and Aqua satellites, and the Landsat 8 satellite.
l Source: National Geographic