Historical anthropogenic contributions to mercury accumulation recorded by a peat core from Dajiuhu montane mire, central China

Abstract

Mercury (Hg) accumulation records spanning the last 16,000 years before present (yr BP, relative to AD 1950) were derived from a peat core collected from Dajiuhu mire, central China. The natural Hg concentration and accumulation rate (free from anthropogenic influence) were 135.5 ± 53.9 ng g−1 and 6.5 ± 4.5 μg m−2 yr−1, respectively. The increase in Hg flux that started from a core depth of 96.5 cm (3358 cal yr BP) is independent of soil erosion and organic matter content. We attribute this to an increase in atmospheric Hg deposition derived from regional anthropogenic activities. Anthropogenic Hg accumulation rates (Hg-ARA) in the pre-industrial period peaked during the Ming and the early Qing dynasties (582–100 cal yr BP), with Hg-ARA of 9.9–24.6 and 10.7–24.4 μg m−2 yr−1, respectively. In the industrial interval (post∼1850 AD), Hg-ARA increased progressively and reached 32.7 μg m−2 yr−1 at the top of the core. Our results indicate the existence of regional atmospheric Hg pollution spanning the past ∼3400 years, and place recent Hg enrichment in central China in a broader historical context.