Geographical distribution of polycyclic aromatic hydrocarbons in estuarine sediments over China: Human impacts and source apportionment

Human activity is suggested to increase polycyclic aromatic hydrocarbons (PAHs) pollution and also cause PAHs' sources complex in estuarine environments. However, the human impacts and source apportionment of PAHs in estuarine sediments at a continental scale remains poorly understood. In this study, we investigated geographical distribution of PAHs and used the compound-specific carbon isotope approach to characterize the sources of PAHs in the sediments of estuaries along the latitudinal gradient over China. We also used human population and economic size to characterize the human impacts on PAHs pollution in the estuaries. The concentrations of total PAHs (Sigma(16) PAH) in wet and dry seasons ranged from 60.9 to 330.7 ng g(-1) and from 103.9 to 620.6 ng g(-1), respectively, across the estuaries. At the continental scale, the concentrations of PAHs were significantly higher in dry than in wet seasons. The proportions of low molecular weight (LMW, 2-3 ring PAHs), middle molecular weight (MMW, 4 ring PAH) and high molecular weight (HMW, 5-6 ring PAHs) of PAHs varied largely across the estuaries, with being in a range of 26.4-48.5%, 17.2-34.1%, 25.3-46.8% in wet season and in a range of 24.0-58.4%, 18.4-52.4%, 21.8-48.6% in dry season. The concentrations of PAHs were found to be significantly correlated with per capita GDP throughout the studied estuaries. The delta C-13 of individual PAH ranged from -26 to -32 parts per thousand and from -24 to -29 parts per thousand in dry and wet seasons, respectively. The main sources of PAHs indicated by the delta C-13 across the estuaries were coal-processing and biomass combustion. These results suggest that the increasing human activities intensity can increase the PAHs pollution in sediments of the estuaries. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

This study investigated the geographical distribution of PAHs in estuarine sediments along different latitudes in China, using a compound-specific carbon isotope approach to characterize the sources of PAHs. It was found that human activities significantly impact PAHs pollution in estuaries, with coal processing and biomass combustion being identified as the main sources of PAHs.