Short-term fluctuations in heavy metal concentrations in Antarctic snow

Heavy metal variations in polar ice cores may reflect changes in global airborne pollution1. Reported profiles from Antarctica1–3 and Greenland4, where sampling resolution was normally larger than a year, have shown a much greater variability than can be reasonably accounted for by variations in the annually smoothed emissions of anthropogenic sources and most natural sources. Volcanism has been invoked4 to account for major features. We now report data from a finely resolved sample sequence from a remote plateau region of the Antarctic Peninsula. Variations of similar magnitude to those reported for longer time series occur also on the scale of seasonal changes and even of single snowfalls; these must be controlled by meteorological processes. We conclude that changes in large-scale transport processes and depositional mechanisms on longer tune scales may have as important a role as emission rates in generating the concentration profiles observed in deeper ice cores.