A 150 years record of polycyclic aromatic compounds in the Sihailongwan Maar Lake, Northeast China: impacts of socio-economic developments and pollution control

The geochemical composition of sediment cores can serve as a proxy for reconstructing past human and nature-driven environmental and climatic changes. We investigated the temporal variation in the concentrations and fluxes of polycyclic aromatic compounds (PACs) which include polycyclic aromatic hydrocarbons (PAHs), oxygenated PAHs, and azaarenes in the Sihailongwan Maar Lake and found that they remained low before 1950. The PAC concentrations and fluxes increased substantially since 1950, which was in good agreement with the fast socio-economic development, industrialization, and associated growth in fossil fuel consumption in China, particularly since the 1980s. After 2010, the PAC fluxes decreased, which was consistent with the implementation of air pollution control policies in China at that time. The concentration ratios of the sums of low to high molecular weight PAHs (LMW-PAHs/HMW-PAHs), benzo[e]pyrene/benzo[a]pyrene, and benzo[a]anthracene-7,12-dione/benzo[a]anthracene all decreased from bottom to top of the sediment core, reflecting the rapidly increasing contribution of emissions derived from high-temperature fossil fuel combustion (energy, transport and industry) to the PAC emissions in recent times at the expense of biomass burning. In addition, these data reflect the increasing local sources of PACs in more recent times because of the enhanced human activities in the area surrounding the Maar lake. Our results demonstrate that PAC fluxes and concentrations in sediment cores reflect the regional and national economic development and the efficiency of pollution control measures.