Atmospheric mercury accumulation rate in northeastern China during the past 800 years as recorded by the sediments of Tianchi Crater Lake.

An evaluation of the history of anthropogenic mercury (Hg) emissions is needed to quantify total atmospheric Hg emissions since the Industrial Revolution. Thus more long-term records of Hg accumulation rate from natural archives are needed. In the present study, a sediment core from Tianchi Lake, a crater lake in northeastern China, was used to reconstruct atmospheric Hg accumulation rates during the past 800 years. The results show that both Hg concentration and Hg accumulation rate began to increase from 29.5 to 40.2 ng g-1 and from 1.44 to 2.26 μg m-2 yr-1, respectively, at ~ 1750 AD, synchronous with the initiation of the Industrial Revolution. The Hg accumulation rate and Hg concentration increased significantly at ~ 1850 AD, and subsequently, there were two prominent peaks, at ~ 1940 AD and ~ 1980 AD, which are temporally consistent with the Second World War and the peak in commercial usage of Hg, respectively. The Hg accumulation rate and Hg concentration decreased after ~ 1980 AD, possibly because of the decrease in the global Hg background at that time. Differences in regional Hg emissions and atmospheric circulation may be responsible for the different trends in Hg accumulation rate after ~ 1980 AD in the Tibetan Plateau and northeastern China. Our results provide new data for evaluating natural and anthropogenic Hg emissions to the atmosphere in China.