Polycyclic aromatic hydrocarbons in intertidal surface sediments of mangrove wetlands in Dongzhai Harbor, Haikou, China: Understanding sources, distribution, and ecological risk

Polycyclic aromatic hydrocarbons (PAHs) can be stored for long periods in soil or sediments, especially in sediments containing large amounts of organic matter, because of their special properties. Due to the high organic matter content in mangrove forests, this area serve as natural reservoir or a "sink" for persistent organic pollution. For this reason, sediment and soil samples were obtained from the mangrove wetland in Dongzhai Harbor, Hainan, to examine the distribution of PAHs concentration, source, and ecological danger. The PAHs content varied from 69.94 to 1481.91 ng center dot g-1 and presented a mean of 244.44 ng center dot g-1. The maximum PAHs concentration of 1481.91 ng center dot g- 1 occurred at station DZ-03 which located at the innermost of the harbor. The PAHs concentrations in the other stations ranged within 69.94-356.66 ng center dot g- 1, and the average value was 131.95 ng center dot g-1, which denotes a medium to low pollution level. The diagnostic ratio approach and principal component analysis revealed that the primary source of PAHs was the combustion of coal and biomass. The majority of the PAHs at Station DZ-03 showed high potential danger according to the ecological risk assessment. At the other stations, Ace and BghiP pose danger while the potential risk of the other PAHs was low. TEQBaP revealed high concentrations at Station DZ-03 and low concentrations at the other stations, where the overall potential ecological risk was low. Nevertheless, PAHs emissions should still be given attention, and the burning of fossil fuels and biomass should be reduced to decrease the potential ecological risk.