Lake Sediment Archive Reveals a Distinct Response to Anthropogenic Pb and Zn Deposition with Historical Periods: Pb-Zn Isotope Evidence

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 Pb-210-dated sediment core collected from the enclosed lake in South China. We observed a progressive shift toward higher Pb-208/Pb-206 and Pb fluxes (0.79-4.02 mu g center dot cm(-2)center dot a(-1)) from 1850 to 1950 and a consistent decrease in delta Zn-66(IRMM) (as low as -0.097 +/- 0.030%) coupled with an increase in Pb (1.74-3.36 mu g center dot cm(-2)center dot a(-1)) and Zn (8.07-10.44 mu g center dot cm(-2)center dot 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.

Automated summary

Anthropogenic activities release heavy metals into the atmosphere, and Pb and Zn isotopes can be used to determine their sources. The study found that the Pb in sediment cores from a lake in South China is mainly from trans-boundary transportation, with 72.3% coming from previously industrialized countries, indicating a significant legacy of heavy metals in China since 1900. Additionally, Chinese gasoline still contributes to heavy metal pollution, and China's mining and smelting activities have steadily increased their contribution to Pb since 1980.