Historical input and sources of polycyclic aromatic hydrocarbons in aquatic sediments†

Polycyclic aromatic hydrocarbons (PAHs) are persistent organic pollutants whose presence in the environmental matrices can provide insights into historical emissions and inputs from surrounding areas. In this study, we analyzed ten PAHs in eight sediment cores collected from the northern part of Taihu Lake, a region adjacent to one of the most developed areas in China, to assess the impacts of anthropogenic activities on PAH distributions over recent decades. PAH distributions were characterized using concentration fraction profiles of four light PAHs (CFL) and six heavy PAHs (CFH). The results reveal a consistent upward trend of increasing CFH and decreasing CFL within the sediment cores. This pattern is primarily attributed to the substantial rise in coal and oil consumption in the local region over recent decades, given that heavy PAHs are mainly emitted from coal combustion and vehicle exhaust rather than from wood combustion. Additionally, heavy PAHs preferentially bind to ultrafine particles which are less efficiently captured by conventional particle interception technologies, causing them to be more prone to environmental release. Expanding the analysis globally, four distinct types of CFH and CFL profiles were identified in 19 other aquatic areas, reflecting variations in regional energy consumption structures and industrialization levels. By integrating data on energy use, emission sources, PAH partitioning and sedimentary deposition patterns, this study provides a comprehensive framework for interpreting the historical and regional characteristics of PAH input to the aquatic environment.