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.