High-resolution industrial history archived by artificial radionuclides in Lake Khanka’s (Xingkai) sediments and catchment

Abstract

Lake sediment is continuously formed by gradually atmospheric deposition of air particles and the riverine input, it records information of environmental changes in the past year. Accumulated history of human industrial activities, especially since the 1950s, was reconstructed through analysis of sediment cores collected in Lake Khanka (Xingkai) located in the East Asia. Sediment cores collected from different locations in Lake Khanka (Xingkai), as well as surface soil surrounding the lake and sediment of the Spasovka River flowing into Lake Khanka (Xingkai) were analyzed for artificial (¹³⁷Cs, ^239,240Pu, ²⁴¹Am, ²³⁷Np) and natural (²³⁸U, ²³²Th, ⁴⁰K) radionuclides. Varied sedimentation rate across sections of Lake Khanka (Xingkai) was observed, which is mainly influenced by particles load in the inflowing rivers and the distance to the mouth of the inflowing rivers. The level, distribution of temporal variation of anthropogenic radionuclides ¹³⁷Cs, plutonium isotopes, ²³⁷Np and ²⁴¹Am in the sediments and soil indicate that this area only received global fallout without local sources of contamination. Intensive leaching of ⁴⁰K from the catchment area of Lake Khanka (Xingkai) was detected, which might attribute to the soil features of this area. We demonstrate the preponderance of sediment runoff for radionuclide migration in the sediment column over diffusion and chemical processes.Anthropogenic pressure on Lake Khanka (Xingkai) is reflected in sedimentation rates linked to land use, while artificial radionuclides serve as precise tracers of radioactive contamination linked to the global fallout, providing a chronological archive of human impact without local contamination signals.