69 Paleolimnological Studies of Climate Variability and Environmental Response (Posters)

Tuesday, 21 March 2017
1:30 PM - 5:30 PM
Grand Ballroom, 17th Floor

ISOTOPIC RECORD OF ANCIENT AND PRE-HISTORIC LEAD POLLUTION IN LAGUNA ROYA LAKE SEDIMENTS, NORTHWESTERN SPAIN

Paper number: 69-13
Program: Theme Sessions
Time: 1:30 PM – 5:30 PM

Authors

Abstract

This study presents a 4,000 year lake sediment record of atmospheric lead deposition from Laguna Roya (42° 8'8.42"N, 6°47'38.95”E), a small glacial lake located in the Sierra Segundera of Northwestern Spain. An increase in lead concentrations, and a decrease in 206Pb/207Pb ratios, after 900BC in the sediment record. This is coincident with archeological evidence that suggest the onset of the Iron Age in the region at this time. An abrupt acceleration of atmospheric lead deposition, accompanied by a dip in 206Pb/207Pb ratios occurs shortly after the Roman conquest of the region in 29BC. These shifts reach a peak at ~130AD. After the fall of the Roman Empire, the anthropogenic lead deposition input decreases but remains relatively constant, with depleted 206Pb/207Pb ratios compared to the background signature. Another lead deposition peak of interest occurs in the late middle ages ~1000AD. The timing of this increased lead input is inconsistent with existing local archeological and historical mining records but coincides with the findings of similar multiproxy studies in the region. Source appointment of atmospheric pollution will be estimated using isotopic fingerprinting techniques using ratios of lead’s four stable isotopes 204Pb, 206Pb, 207Pb and 208 Pb. Ratios of these four lead isotopic compositions measured in the Laguna Roya sediment samples, will be compared with known lead isotope values from ore bodies of ancient mining sites throughout Spain and Europe. It is often difficult to determine accurate timing, or intensity of mining and metallurgical activities due to lack of archeological evidence. Lake sediments, and isotopic fingerprinting, in such cases, can serve as valuable archives through which past regional environmental conditions can be elucidated.

Geological Society of America Abstracts with Programs. Vol. 49, No. 2

doi: 10.1130/abs/2017NE-290913

© Copyright 2017 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.