Polycyclic aromatic hydrocarbons in surface sediments of Lingshui county lagoons: distribution, source analysis, and ecological risk assessment

Abstract Lingshui county lagoons are Hainan's first marine special protection area. To investigate the contamination levels and ecological risks of 16 polycyclic aromatic hydrocarbons (PAHs) in the surface sediments of the lagoons, surface sediment samples were collected from 42 sampling sites in the lagoons in April 2025. The concentrations and compositions of PAHs were determined using gas chromatography-mass spectrometry (GC-MS). The source of contamination was analyzed using the characteristic compounds ratio method and positive matrix factorization (PMF). The ecological risks were evaluated using both individual PAHs and comprehensive ecological risk assessments. The results showed that the PAHs concentrations in the surface sediments ranged from 18.12 to 111.3 ng/g (dry weight), with an average concentration of approximately 60.83 ng/g. The proportions of PAHs with different ring numbers were as follows: hexacyclic (52.43%) > tetracyclic (21.04%) > pentacyclic (16.73%) > tricyclic (7.09%) > bicyclic (2.71%). The results of the PMF model analysis indicate that the primary sources of pollution in the lagoons are human activities. The contribution rates of the six pollution sources are as follows: petroleum sources and biomass fuel sources account for 15.92%, gasoline fuel sources account for 22.92%, coal combustion sources account for 21.65%, diesel fuel sources account for 17.04%, and coke sources account for 7.60%. and commercial phenolic oil at 14.87%. The concentration of PAHs in the surface sediments of the lagoon in Lingshui County is at a medium to low pollution level, and the potential ecological risk of PAHs in the surface sediments of this sea area is relatively small.