Washington DC--It's often thought that humans began modifying our environment over large regions relatively recently, aided and abetted by modern technology. Now, a report by researchers at the University of Berne as well as universities in Liverpool, Kiev, and Copenhagen, helps show that humans have been dramatically altering their surroundings for thousands of years and chronicles the growing effect of humans on atmospheric pollution.
The researchers reconstructed a record of the past showing that human activity has caused lead levels to soar above what they once were naturally, and that this activity began as far back as 6,000 years ago. William Shotyk, of the University of Berne, and his colleagues analyzed changing levels and sources of lead in the atmosphere over the last 14,000 years by studying layers of peat in an ancient bog in Switzerland's Jura Mountains. The data suggest that everyone from the first plant cultivators in Europe, to miners of the Roman Empire, to Medieval silversmiths in Germany, to European petroleum companies in the 1970's, has left their mark on this peat bog by releasing lead or dust containing lead to the air. In the study, which will appear in the 11 September issue of Science, researchers traced natural variations in atmospheric lead and dust associated with the retreat of the large ice sheets from Scandinavia.
While peat bogs and ice cores have been used to analyze atmospheric lead
levels for small increments of time and back to several thousand years ago,
Shotyk and his colleagues present the first complete record to span
approximately 14,000 years--nearly the entire time since the last ice age. They
were therefore able to contrast the first 8,000 years of natural lead emissions
with the contributions that humans made over the years that followed.
To accomplish this task, the researchers took advantage of an unusual
characteristic of most peat bogs, namely tha
Contact: Diane Dondershine
American Association for the Advancement of Science