Decadal trends of black carbon and heavy metal accumulation in a lake sediment core from central China: A historical perspective

Black carbon (BC) and heavy metal are vital indicators of historical human activities. This study investigates the historical pollution trends of BC, char, soot, and heavy metals in lake sediments from Yinjia Lake (YJL). BC, char, and soot concentrations exhibit similar historical trends, with average values of 1.59, 1.27, and 0.32 mg/g, respectively. Char, constituting 67.25-85.85 % of BC, indicates a dominant fraction in the lake. A notable increase in BC, char, and soot was observed post-1955, peaking in 2005, followed by a decline, reflecting local economic development and anthropogenic activities. Heavy metals, including Cu, Cd, Zn, Pb, Cr, Co, Ni, and Mn, also displayed a significant increase post-1950, with Cd showing an exceptionally high concentration. The average deposition fluxes of BC, char, and soot were consistent with their concentrations, peaking in 2005. The correlations between BC, char, soot, and heavy metals suggest BC's role as a metal carrier, influenced by industrial and anthropogenic emissions. The char/soot ratio analysis indicates predominant biomass burning pre1950 and increased fossil fuel combustion post-1950, with regional variations observed. The study highlights the impact of industrialization, urbanization, and policy changes on pollution trends in YJL.