Characterizing the long-term occurrence of polycyclic aromatic hydrocarbons and their driving forces in surface waters

As carcinogenic and ubiquitous pollutants, an in-depth understanding of the long-term environmental behaviors of polycyclic aromatic hydrocarbons (PAHs) and their driving forces is crucial for reducing human health risks. Based on long-term monitoring data from 2001 to 2016, this study systematically investigated the temporal and seasonal trends, periodic oscillation, source apportionment, and human health risks of PAHs in eight rivers in the Free State of Saxony, Germany. The results showed that the annual average ∑16PAHs (sum of 16 PAH concentrations) ranged from 28.2 ng L−1 to 202 ng L−1. Using the Mann–Kendall test, a trend of decreasing PAH concentrations was determined (slope range: −0.103 to −0.0159). Wavelet analysis indicated that the most significant periodic oscillation of PAHs was 10–30 months, with more pollution in winter. Source apportionment analysis suggested that vehicular emissions and coal combustion contributed the most to PAH concentrations (20.6–40.3% and 21.7–41.4%, respectively) and related health risks (54.1–80.1% and 5.61–37.9%, respectively). Furthermore, the risks (oral lifetime: 4.24×10−7–1.34×10−6; dermal lifetime: 2.86×10−5–9.05×10−5) were determined to be low. The data revealed that the substitution of petroleum and coal with cleaner energy would facilitate the mitigation of PAHs. [Display omitted] •Spatial and temporal changes in 16-year concentrations of PAHs were analyzed.•Vehicular emission and coal combustion were identified as the main PAH sources.•Contributions of sources to risks and the uncertainties in eight rivers were assessed.•Anthropogenic activities had great influences on the occurrence of PAHs in rivers.