Distribution, sources and ecological risks of polycyclic aromatic hydrocarbons（PAHs）in surface sediment of Minjiang estuary

As a kind of persistent organic pollutant widely existing in the environment, PAHs (Polycyclic aromatic hydrocarbons) in sediments is highly exposed in estuaries, posing a potential ecological risk to the estuarine environment. In order to study the distribution characteristics, sources and ecological risk of the surface sediments in Minjiang estuary, this study collected 40 surface sediment samples in the area, determined 15 PAHs sources by statistical analysis, ratio method and principal component analysis, and assessed their ecological risk with risk entropy value. The results showed that the total content of PAHs ranged from 9.47 to 197.54 ng/g, with a mean value of 89.91 ng/g. The main components were 4-5 ring PAHs, with the 4-ring PAHs accounting for the highest proportion, but this area remains lower polluted in comparison with other estuaries. Among different types of sediments, clayey chalk has the highest average PAHs content and the biggest proportion of 4-5 ring PAHs. The sediments’ PAHs mainly originated from combustion sources, including coal, biomass and oil combustion. The ecological risk assessment indicates that some of the individual PAHs in the surface sediments of the Minjiang estuary are at moderate ecological risk, with BbF reaching the severe level of ecological risk. Therefore, it is urgent to strengthen relative control measure. The results of the study can provide a scientific basis for marine environmental protection in the Minjiang estuary.