Increasing heavy metals in the background atmosphere of central North China since the 1980s: Evidence from a 200-year lake sediment record

Long-term trends of atmospheric compositions are significant for assessing the influence of human activities on the atmosphere and protecting the atmospheric environment. In this study, based on heavy metal concentrations and Pb isotope ratios in a well-dated sediment core from a remote alpine lake in central North China, anthropogenic fluxes of As, Cd, Sb, and Pb were reconstructed and heavy metal evolutions in the atmosphere were revealed in the last 200 years. The heavy metals in the atmosphere were generally natural origins before 1980 A.D. Since the 1980s they began to increase gradually, but they increased the most in the 1990s resulting from rapid developments of rough and high energy-consuming industries in North China. After entering the 21st century the industries still developed rapidly, but the atmospheric Pb ceased increase and the As and Sb even decreased in the 2000s due to (1) phasing out of leaded gasoline and (2) implementing stricter industrial emission standards in 2000 A.D. in China. However, in the 2000s the atmospheric heavy metals still kept at a relatively high level and even likely began to increase again in the 2010s. Considering the lake relatively remote and seldom affected by local human activities, the results likely reflect heavy metal evolutions in the regional background atmosphere of central North China at the annual/decadal timescale in the last 200 years.