Characterization, ecological risk assessment and source diagnostics of polycyclic aromatic hydrocarbons in water column of the Yellow River Delta, one of the most plenty biodiversity zones in the world

As one of the most active regions of land-ocean interaction among the large river deltas in the world, the Yellow River Delta (YRD) gains increasing concern on its ecological and environmental conditions. However, few studies on polycyclic aromatic hydrocarbons (PAHs) have been reported for this area. In this study, the distribution characteristics, probabilistic risk and possible sources of PAHs were investigated in the water column of the YRD. The PAH concentrations were found to be at relatively low or medium levels (121.3 ng L−1 in water and 209.1 ng g−1 in suspended particulate matter (SPM) on average), and the result of probability risk assessment additionally elucidated low PAH ecological risk in the YRD. The PAH composition showed that low and moderate molecular PAHs were the major species in water phase, whearas the SPM showed a different proportion of each PAH composition. An interesting result was found that low-ring PAHs and salinity in this land-ocean interaction area had a positive relationship (R = 0.609). For PAH source identification, both diagnostic ratios of selected PAHs and principal component analysis (PCA) with multiple linear regression (MLR) analysis were studied, suggesting mixed sources of pyrogenic and petrogenic deriving PAHs in the YRD.