Antarctica is an isolated continent but due to the global atmospheric circulation, it keeps a record of the evolution of the terrestrial paleoclimate [1] written in its ice layers. Contaminants like lead, emitted in the mid latitudes, get deposited in Antarctica. This is a toxic contaminant naturally present in the atmosphere in very low concentrations (blue region in the plot) and presents a distinct isotopic signature [2] that is directly related to the type of source, making it a great indicator for industrial pollution.

The study of 16 ice cores [3] showed that the lead contamination in Antarctica started in the beginning of the 20th century and still persists to this day. Unlike the Arctic where lead pollution peaked in the 1970s, lead pollution in Antarctica was as high in 1889 as it is now, beating polar explorers by more than 22 years.

Between 1650 and 1885, lead concentrations gradually increased from ~0.6 pg/g to ~1.8 pg/g [4]. Concentrations remained high until the late 1920s, with a temporary low during the Great Depression and again at the end of World War 2. From here on, lead concentrations increased rapidly to 5.7 pg/g by 1975 and remained elevated until the mid-1990s. Concentrations during the early 21st century were lower than the peak 20th century concentrations but well above background levels before the start of the Industrial Revolution. Snowfall in Antarctica has been increasing which in turn can influence the amount of lead deposited there. Nevertheless, this fact does not explain, by itself, the increase in the lead concentrations found in the Antarctic continent.

[1] Paleoclimate – Climate from an old geologic period

[2] Lead has 4 natural stable isotopes. In its natural state are: Pb-204 (1.4%), Pb-206 (24.1%), Pb-207 (22.1%) e Pb-208 (52.4%)

[3] Ice/rock/soil sample, extracted usually using a hollow pipe that allows the sample to remain intact

[4] Unit of measure: pg or picogram = 10-12 grams

Source:

———–

McConnell, J.R., Maselli, O.J., Sigl, M., Vallelonga, P., Neumann, T., Anschütz, H., 

Bales, R.C., Curran, M. a. J., Das, S.B., Edwards, R., Kipfstuhl, S., Layman, L., Thomas, E.R., 

2014. Antarctic-wide array of high-resolution ice core records reveals pervasive lead pollution 

began in 1889 and persists today. Sci. Rep. 4. doi: 10.1038/srep05848

Author: Eduardo Amaro