Exploring 4200 Years of Mercury Variation in the Antlers of High-Arctic Wild Reindeer

Anthropogenic mercury (Hg) emissions and climate change are altering the global cycle of Hg. Levels of Hg in natural archives can help us understand not only the historical trends but also the future changes in different ecosystems, including the Arctic. In this study, we investigated the temporal variation of Hg across 4200 years in 78 antlers of the high-Arctic Svalbard reindeer (Rangifer tarandus platyrhynchus). Antler Hg concentrations were higher during the pre-1650 Anno Domini (AD) period compared to the post-1650 AD period. Thus, antler Hg concentrations did not reflect the increased environmental Hg levels caused by high anthropogenic activities during the past three centuries. Trabecular Hg concentrations tended to be higher during the Medieval Warm Period than during the Little Ice Age, as revealed by a post-hoc analysis conducted to explore the relationship between climatic variation and antler Hg concentrations. The overall mean (±SE) antler Hg concentration was generally low (5.29 ± 0.46 ng/g) compared to the present levels of Hg in various tissues of terrestrial Arctic ungulates. Combined with other paleo-archives, this millennial-scale study of Hg using antlers could provide insights into the temporal patterns and potential drivers of Hg variation in Arctic terrestrial ecosystems.