The study of Canadian Arctic freshwater system toward radioactive contamination - status in 1999

This work provides a novel data set on accumulations of both anthropogenic (¹³⁷Cs, ²³⁸Pu, ^239+240Pu, ²⁴¹Am) and natural (²¹⁰Pb, ²²⁶Ra, ²³²Th) radionuclides and an element (K). Sampling of soils and lake sediments was accomplished in 1999 during Tundra Northwest (TNW-99) international expedition to a remote region of the Canadian Arctic. The sediment ages and sedimentation rates were determined. The obtained results overall indicated a high geographical diversity of contamination levels and trends. Accumulation rates were also differential, and a sediment focusing contribution was distinctly visible. Radioactive pollution was found to be lower relative to temperate counterparts. The activity ratios of anthropogenic radionuclides corresponded to global fallout as a prevailing source in the entire examined area. The post-Chernobyl radiocaesium was observed for the westernmost lake only. The elevated level of ¹³⁷Cs and ^239+240Pu in the topmost sediment at the northern and eastern Arctic Archipelago was attributed to recent resuspension and subsequent redistribution of radionuclides.