LANZHOU -- Chinese scientists have made new progress in understanding the persistent organic pollutants (POPs) in permafrost regions, according to the Northwest Institute of Eco-Environment and Resources (NIEER) under the Chinese Academy of Sciences.

The study conducted systematic research and in-depth exploration of the environmental behavior of a new type of POP, hexachlorobutadiene (HCBD), in the Arctic region, with the findings published in the journal Environmental Pollution, according to NIEER.

The Arctic permafrost region is sensitive to climate change and is considered an important accumulation zone for POPs. The NIEER study team carried out the collection and analysis of permafrost samples in Alaska, and systematically revealed the occurrence characteristics of HCBD in the permafrost of this region.

The study also obtained HCBD concentration data from different permafrost profiles, providing important basic data for a deeper understanding of the migration and transformation process of POPs in high-latitude cryosphere environments.

A first-order mass balance estimate indicates a total burden of approximately 160 tonnes of HCBD sequestered within the top 30 centimeters of Alaskan permafrost, providing a conservative baseline for its regional inventory. This figure demonstrates that Arctic permafrost is not only a massive global carbon pool but also a major storage site for POPs, according to Zhang Yulan, a researcher at the NIEER who led the study.

The random forest model identified dissolved organic carbon as the dominant factor controlling HCBD distribution, highlighting the key role of dissolved organic matter-mediated transport regulated by soil pH and electrical conductivity.

"The study indicates that permafrost is shifting from a pollution 'sink' to a potential 'emission source' under continued thawing," Zhang said.

"The findings will help deepen our understanding of the behavior of POPs in permafrost environments and also provide crucial scientific support for assessing polar ecological risks and formulating global chemical regulatory policies," Zhang added.