Lake sediment records of persistent organic pollutants in Southern Siberia mirror the changing fortunes of the Russian economy over the past 70 years

• Main Authors: Adams, Jennifer, Martins, César, Rose, Neil, Shchetnikov, Alexander, Mackay, Anson
• Format: Report
• Language: unknown
• Published: EarthArXiv 2017
• Subjects: Life Sciences; Ecology and Evolutionary Biology; Terrestrial and Aquatic Ecology; Environmental Chemistry; Environmental Sciences; Physical Sciences and Mathematics; Chemistry; permafrost; Siberia
• Online Access: https://dx.doi.org/10.17605/osf.io/q3t8w; https://doi.org/10.31223/osf.io/q3t8w

Persistent organic pollutants (POPs) have previously been detected in the surface sediments, water, and endemic organisms of Lake Baikal, a UNESCO World Heritage Site. The Selenga River is the primary source of freshwater to Lake Baikal, and transports pollutants accumulating in the Selenga River basin to the lake. Sources of POPs in the Selenga River basin have grown through the 20th and the 21st centuries. In the present study, temporal changes in the concentrations of polycyclic aromatic hydrocarbons (PAHs) and halogenated organic compounds (HOCs) were reconstructed from two lakes in the Selenga River basin over the past 150 years using paleolimnological techniques. Increased concentrations in PAHs and PCBs were recorded initially in the 1930s. Concentrations peaked in the 1960s and 1980s, and declines in concentrations and fluxes were recorded for most POPs in the 1980s and 1990s. Overall, the 1940s to 1980s was the period of greatest exposure of the Lake Baikal ecosystem to organic contamination from the Selenga River basin, with peak concentrations of PCBs, DDTs, HCHs and many PAHs during this time. Temporal trends in total PAH, ∑HMW PAH, and ∑PCB concentrations indicate that both local and regional sources have contributed to southeast Siberian environmental contamination in the 20th and 21st centuries. Temporal variations in PAHs, PCBs, DDTs, and HCHs can be linked to economic and industrial growth in the former USSR after World War II and the economic decline of Russia in the late-1980s and early-1990s, as well as global trends in industrialization and development during the mid-20th century. Understanding long-term records of contaminant change is crucial to determining the potential burden the region might face in the future with increased mobility of previously contained contaminants, due to thawing permafrost and increased catchment soil erosion linked to rapid regional warming.