Polycyclic aromatic hydrocarbons (PAHs) pose significant environmental and health risks in freshwater ecosystems. However, understanding their spatio-temporal dynamics in integrated lake-river systems, particularly with year-round seasonal coverage, remains limited. This study addresses this gap by employing seasonal sampling across all four-quarters (2018–2019), Positive Matrix Factorization (PMF) source apportionment, and risk assessment frameworks to elucidate PAH distribution, composition, sources, and ecological/health risks in Lake Taihu and its connected rivers. Results indicate PAH concentrations in surface water range from 44.8 to 317.5 ng/L, characterized by 3- and 4-ring compounds, wherein phenanthrene (Phe) serves as the primary congener. In sediments, PAH levels fluctuate from 221.2 to 1133.6 ng/g in the lake and 151.1–4473.3 ng/g in rivers, with acenaphthylene (Acy) and Phe prevalent in 3-ring fractions, whereas 6-ring PAHs (e.g., indeno 1,2,3-cdpyrene) were markedly enriched in sediments. Spatial distributions showed higher PAH concentrations in the western coastal zone of the lake and associated western inflow rivers, driven by urban runoff and industrial inputs. PMF analysis identified four major sources: petroleum-related, coal combustion, traffic emissions, and biomass burning, with combustion processes collectively dominating (80%). Risk assessments revealed low overall ecological and carcinogenic risks in water (with elevated concerns only at localized western coastal hotspots), whereas river sediments exhibited significantly higher PAH levels and guideline exceedances than lake sediments, with Acy emerging as the predominant ecological risk driver. These findings provide a systematic, year-round characterization of PAH dynamics across the lake-river continuum, offering critical insights for integrated management strategies to mitigate contamination and protect the Taihu ecosystem.
Wan et al. (Wed,) studied this question.