Human impacts on polycyclic aromatic hydrocarbon distribution in Chinese intertidal zones

The intertidal zone—a transitional boundary between terrestrial and marine environments—has important ecological functions, and receives polycyclic aromatic hydrocarbons (PAHs) from human activities, but how and to what extent anthropogenic factors influence the distribution of PAHs in this important niche remain largely unknown. Here we measured the distribution of United States Environmental Protection Agency priority PAHs in samples of intertidal sediments from across more than 4,500 km of China’s coastline. The total PAH concentrations ranged from 2.3 to 1,031.7 ng g⁻¹ sediment (dry weight) and all PAHs showed positive correlations with total organic carbon (TOC). TOC-normalized high-molecular-weight (HMW) PAH concentrations, but not TOC-normalized low-molecular-weight (LMW) PAHs, were positively correlated with TOC. Moreover, population size and economic development influenced TOC-normalized HMW PAH concentrations, whereas urbanization had a major influence on TOC-normalized LMW PAHs. Human activities also indirectly influenced TOC-normalized PAH concentrations by affecting TOC. In sum, our investigation provides continental-scale evidence that human activities have key and differential effects on the distribution and deposition of PAHs in intertidal sediments, and shows that pollution status and profile of PAHs can be used to index regional industrialization and urbanization status.