High-Resolution Atmospheric Lead Pollution during the Roman Period Recorded in Belgian Ombrotrophic Peat Cores

Two peat cores from two bogs were used to reconstruct high–resolution changes in atmospheric Pb accumulation rate (Pb AR) in Belgium during the Roman period. The two records were compared to assess the reliability of peat cores as archives of atmospheric Pb deposition and to established histories of atmospheric emissions from anthropogenic sources. To address these issues we analyze Pb concentration and isotopes, using ICP-MS, LA-ICP-MS and MC-ICP-MS in two peat sections, spanning 1000 yr each. Lead concentrations in the two cores range from 0.1 to 60 μg g−1, with the maxima between 15 and 60 μg g−1. The average natural background of Pb AR was 0.005± 0.002 mg m-2 yr-1 and the maximum ranges from 0.7 to 1.2 mg m-2 yr-1 between 50 BC and AD 215. The highest Pb AR exceed the pre-Roman period values by a factor of 25-30. Pb isotopic composition indicates that mining and metallurgical activities were the predominant sources of pollution during the Roman period. The Pb AR and chronologies in the Belgian peat cores are consistent with those reported for other continental archives as lake sediments, peat and ice cores.

High-Resolution Atmospheric Lead Pollution during the Roman Period Recorded in Belgian Ombrotrophic Peat Cores

Two peat cores from two bogs were used to reconstruct high–resolution changes in atmospheric Pb accumulation rate (Pb AR) in Belgium during the Roman period. The two records were compared to assess the reliability of peat cores as archives of atmospheric Pb deposition and to established histories of atmospheric emissions from anthropogenic sources. To address these issues we analyze Pb concentration and isotopes, using ICP-MS, LA-ICP-MS and MC-ICP-MS in two peat sections, spanning 1000 yr each. Lead concentrations in the two cores range from 0.1 to 60 μg g−1, with the maxima between 15 and 60 μg g−1. The average natural background of Pb AR was 0.005± 0.002 mg m-2 yr-1 and the maximum ranges from 0.7 to 1.2 mg m-2 yr-1 between 50 BC and AD 215. The highest Pb AR exceed the pre-Roman period values by a factor of 25-30. Pb isotopic composition indicates that mining and metallurgical activities were the predominant sources of pollution during the Roman period. The Pb AR and chronologies in the Belgian peat cores are consistent with those reported for other continental archives as lake sediments, peat and ice cores.

Ancient Atmospheric Lead Pollution

In the early 90s, evidence was found in ice cores taken from Greenland of increased levels of ancient atmospheric lead, preserved by way of the annual precipitation that eventually formed into ice sheets. Since that time, similar records of atmospheric lead pollution have been uncovered in myriad other naturally forming deposits, including lake sediments and bogs. These records of lead pollution are presumed to reflect an increase in anthropogenic atmospheric lead pollution as metal became more heavily utilized by ancient peoples. This pollution confirmed for many the size and sophistication of the Roman economy. The records exhibit a clear peak around the beginning of the first millennium, roughly the midpoint of the Roman Empire and such levels were not seen again until after the industrial revolution was well underway. This peak in atmospheric lead is thought to show the climax of Roman Industry, followed by a subsequent decline and historians and scientists have sought to use this evidence as a proxy for the ancient world economy, but more specifically for the so called rise and fall of the Roman Empire. This presentation will explore the science behind linking the atmospheric lead pollution to Roman mining activities and why lead pollution is so strongly thought to reflect the roman economy. Alternative theories as to how atmospheric lead was produced in such quantities will be explored, including, increased agriculture and wood burning. Lastly, confounding factors will be considered such as volcanism and other ancient sources, including mining in Asia Minor and Han China.

Climate changes, lead pollution and soil erosion in south Greenland over the past 700 years

A peat core from southern Greenland provided a rare opportunity to investigate human-environment interactions, climate change and atmospheric pollution over the last ~ 700 years. X-ray fluorescence, gas chromatography-combustion, isotope ratio mass spectrometry, peat humification and fourier-transform infrared spectroscopy were applied and combined with palynological and archaeological evidence. Variations in peat mineral content seem to be related to soil erosion linked with human activity during the late Norse period (13th–14thcenturies AD) and the modern era (20thcentury). Cooler conditions during the Little Ice Age (LIA) are reflected by both slow rates of peat growth and carbon accumulation, and by low bromine (Br) concentrations. Spörer and Maunder minima in solar activity may be indicated by further declines in Br and enrichment in easily degradable compounds such as polysaccharides. Peat organic matter composition was also influenced by vegetation changes at the end of the LIA when the expansion of oceanic heath was associated with polysaccharide enrichment. Atmospheric lead pollution was recorded in the peat after ~ AD 1845, and peak values occurred in the 1970s. There is indirect support for a predominantly North American lead source, but further Pb isotopic analysis would be needed to confirm this hypothesis.