Distribution of Priority PAHs in Lake Baikal Bottom Sediments at the Selenga River Confluence

The study presents data on the concentration of polycyclic aromatic hydrocarbons (PAHs) in bottom sediments of Lake Baikal’s coastal zone, specifically in the Selenga shallow waters, during 2018–2023. Using high-performance liquid chromatography (HPLC) with fluorometric detection, the content of 16 priority PAHs was measured, ranging from 12.3 to 218.8 ng/g, with an average of 74.9 ng/g (n = 88). Higher PAH concentrations were observed near river discharges, particularly in the Ust-Kharauz stream. The bottom sediments in the Selenga landfill were classified as having a “low” level of PAH contamination (Σ PAH < 100 ng/g). Divergence coefficient analysis of PAH profiles allowed the sampling stations to be grouped into two groups: Cluster No. 1 (southwestern part of the Selenga WDS) and Cluster No. 2 (northeastern part). The mixed origin of PAHs (pyrogenic and petrogenic) in bottom sediments was determined using molecular ratios analysis, which revealed an increasing proportion of pyrogenic sources and anthropogenic influence from the northeast to the southwest of the Selenga shallow waters.