Increase in anthropogenic mercury pollution over the past centuries in Northeast China as reconstructed from multi-lake sediment cores

The rise in human activities in northeast (NE) China has resulted in increased emissions of environmental pollutants. Their measurement is crucial to evaluate the extent and timing of the longer-term anthropogenic environmental changes. This study presents the measurement of mercury (Hg) concentration and accumulation rate in 11 lake sediment cores from Songnen Plain in NE China to reconstruct the historical deposition of Hg as an indicator of the changing scale of anthropogenic activities. The results demonstrate an increasing trend of Hg concentration, concurrent with the increased anthropogenic emission, beginning from the early 1900s, accelerating through the mid-1950s and slightly decreasing from the late 1990s up-core. The anthropogenic Hg increase coincides with New China's foundation, precipitating social and economic reforms and rapid industrial and economic growth. Measurements of the Hg enrichment factor in all the cores point out anthropogenic contribution to Hg accumulation, and the geoaccumulation index shows the lakes are generally moderately polluted by Hg. The historical trend of the Hg accumulation rate matches the region's temporal progression of biomass burning and fossil fuel consumption. The findings elucidate the extent of anthropogenic pollution in the Anthropocene and underline the importance of identifying Hg sources to reduce emissions and implementation of effective mitigation strategies.