Occurrence of polycyclic aromatic hydrocarbons and their derivatives in the sediment of the three major estuaries in China

Polycyclic aromatic hydrocarbons (PAHs) are the most widespread organic pollutants in estuarine environment. Existing research on the environmental geochemistry of PAHs mostly focuses on a few priority controlled PAHs, which has significant limitations and uncertainties in understanding their environmental behavior and ecological risks. To comprehensively explore the occurrence characteristics of polycyclic aromatic compounds in estuarine environment in China, this study takes surface sediments of the three typical estuarine including Huanghe Estuary, Changjiang Estuary and Zhujiang Estuary as examples to establish a monitoring list of 81 PAHs and their derivatives (including 20 unsubstituted parent PAHs, 11 oxygen-containing PAHs, 9 oxygen-heterocyclic PAHs, 3 sulfur-heterocyclic PAHs and 38 alkylated PAHs) by using of two-dimensional gas chromatograph coupled with time-of-flight mass spectrometry. The results show that 38 alkylated PAHs are the most important components in the three estuarine sediments, The average proportion in the list of 81 PAHs exceeds 50%, but the proportion of 16 priority controlled PAHs is only about 10% on average. Although there was no statistically significant difference in the total content of PAHs and their derivatives among the three estuaries, the correlation between the different types of PAHs and their derivatives was inconsistent, which may indicate the different characteristics of PAH sources and sedimentary in the three estuaries. The results of ecological risk assessment using 81 PAHs as a list are about 4 times higher than those of 16 priority controlled PAHs, which means that it is necessary to expand the monitoring list of PAHs and their derivatives for ecological risk assessment. This research approach helps to correctly assess the ecological risk of aromatic organic pollutants in sediments or other aquatic environments.