Lake Sediment Archive Reveals a Distinct Response to Anthropogenic Pb and Zn Deposition with Historical Periods: Pb–Zn Isotope Evidence
Yafei Xia, Yuhui Liu, Chengshuai Liu, Ting Gao, Runsheng Yin, Qi Meng, Hongchen Wu
Abstract
Anthropogenic activities release large quantities of heavy metals into the atmosphere. In China, the input of these heavy metals through local and trans-boundary atmospheric deposition is poorly understood. To assess this issue, herein, we use Pb and Zn isotopes to constrain the sources of Pb and Zn in a 210 Pb-dated sediment core collected from the enclosed lake in South China. We observed a progressive shift toward higher 208 Pb/ 206 Pb and Pb fluxes (0.79–4.02 μg·cm –2 ·a –1 ) from 1850 to 1950 and a consistent decrease in δ 66 Zn IRMM (as low as −0.097 ± 0.030‰) coupled with an increase in Pb (1.74–3.36 μg·cm –2 ·a –1 ) and Zn (8.07–10.44 μg·cm –2 ·a –1 ) fluxes after 1980. These distinguished isotopic signals and flux variations reveal the presence of trans-boundary Pb since 1900, with the addition of local industrial Pb and Zn pollution after 1980. Up to 72.3% of Pb deposited at our site can be attributed to long-distance transportation from previously industrialized countries, resulting in a noteworthy legacy of Pb in China since 1900. Despite the phasing out of leaded gasoline, Chinese gasoline still contributes an average of 20.9%. The contribution of China’s mining and smelting activities to Pb has increased steadily since 1980 and remained stable at an average of 25.1% since 2000.