A 2000-year record of mercury and ancient civilizations in seal hairs from King George Island, West Antarctica

Abstract

The concentrations of total mercury (Hg T) and three bio-essential elements (phosphor, potassium, sodium) were analyzed in Antarctic seal hairs from a lake core spanning the past 2000 years and collected from King George Island (63°23′S, 57°00 ′W), West Antarctica. The Hg T concentration shows a significant fluctuation while the levels of the three bio-essential elements remain almost constant. The rise and fall of the Hg T concentration in the seal hairs are found to be closely coincided with ancient activities of gold and silver mining using Hg-amalgamation process around the world, especially in the Southern Hemisphere. Briefly, Hg T levels are high during five episodes of extensive gold and silver mining activities—Rome Empire and China Han Dynasty (∼18–300 A.D.), Maya period and China Tang (750–900 A.D.), Incas civilization and Christian Kingdom (1200–1500 A.D.), New world (1650–1800 A.D.), and modern industry period (1840 A.D.–present); they are low during four time periods of reduced gold and silver mining activities—the China Han and Rome fall (since 300 A.D.), Maya fall and Wartime period in China (1050–1250 A.D.), Pizarro coming (ca. 1532 A.D.) and Independence War of South America (1800–1830 A.D.). Two profiles of Hg T in other two lake cores, one affected by seal excrements and the other by penguin droppings, from the same region are similar to the one in seal hairs. The Hg concentration profile in the seal hairs is significantly correlated with the one in a peat bog of Southern Chile near King George Island. Since Hg is existent mainly at the form of methyl-mercury in seal hairs, this correlation supports a relationship and link between atmospheric mercury concentration and methyl-mercury production. Comparing with samples from American and European continents, the Antarctic seal hairs provide an archive of total mercury concentration in surface seawater of the South Ocean less affected by regional human activities, and this archive may provide a good reference for assessing the global Hg emissions, depositions and recycling in the past thousand years.