The Interannual Evolution of PAHs in Columnar Sediments in Offshore Area of Changxing Island Industrial Zone, China.

Changxing Island, located in the northwest of Dalian City in Liaoning, China, is a beautiful island on the West side of the Liaodong Peninsula. Since 1980, along with the development of the economic benefits and the environmental evolution of the Changxing Island marine belt, its ecological environment has changed to a certain extent. In this paper, the interannual evolution and organic pollution of polycyclic aromatic hydrocarbons (PAHs) in borehole core samples were studied, based on the survey data of coastal substrates and sedimentation chemistry of two columnar stations (C4 and C6) in Changxing Island, China, in 2017. It was found that the distribution of PAHs in the region was controlled by sedimentary types and hydrodynamic factors. The PAH content in the vertical direction of the borehole part was at the level of the environmental background value before 1980. However, from 1981 to the present, the overall increasing trend of PAHs content was evident, and there were obvious fluctuations with the changes of the surrounding environment. In the C4 column, the total concentration of 16 PAHs was 32.8-349.0 ng/g (dry weight), and it was 22.2-81.3 ng/g (dry weight) in the C6 column. Among them, the concentration range of PAHs species composition was from high to low, followed by tricyclic, quadricyclic, bicyclic, pentacyclic, hexacyclic, and the monomer with the highest content in the sea area was tricyclic phenanthrene. The supports were thereby provided for environmental pollution research, comprehensive evaluation, environmental carrying capacity forecasting, and early warning in this region, and it was served as the basis for development and antipollution feasibility demonstration.