Linking sedimentary PAH occurrence forms to precision lake pollution management: Multidimensional insights via three...

The environmental behavior and ecological risk of organic pollutants in sediments are determined by their occurrence forms, yet current lake management primarily relies on extractable fractions. This study systematically examines three polycyclic aromatic hydrocarbon fractions (bioaccessible (B-PAHs), extractable (E-PAHs), and non-extractable (NE-PAHs)) in the representative Luhu Lake sediments, revealing their critical implications for pollution management. Total PAHs (T-PAHs: 101.25-458.04 ng g^-1) significantly exceeded E-PAHs (40.81-316.81 ng g^-1), with NE-PAHs contributing 26-60 %, shifting pollution levels from mixed "moderate/light" (E-PAHs-based) to uniformly "moderate" (T-PAHs-based). Although four sources were identified for both E-PAH and T-PAH datasets, incorporating NE-PAHs altered source contributions: traffic emission decreased from 45.3 % (E-PAHs) to 26.1 % (T-PAHs), while coal burning increased from 30.4 % to 51.7 %. Traffic emission-derived PAHs demanded prioritized control due to its higher ecotoxic extractable fractions. Bioaccessibility assessments revealed comparable B-PAHs in central and shoreline sediments, but central sediments exhibited lower bioaccessible fractions (11.16 % vs. 24.10 %), attributed to organic matter content and aging effects. Exceptionally high B-PAHs at LH27/LH33 (99.69-113.71 ng g^-1) indicated fresh PAH inputs requiring targeted intervention. This study demonstrates that integrating NE-PAHs and B-PAHs enhances pollution level awareness, source quantification precision and risk assessment accuracy, advocating for multi-fraction PAH analysis to optimize lake sediment management strategies.