Polycyclic aromatic hydrocarbons in the surface soil of Shanghai, China: Concentrations, distribution and sources

摘要

We quantified 18 polycyclic aromatic hydrocarbons (PAHs) in 54 surface soil samples covering an area of 6400 km(2) in Shanghai. An isopleth map of total concentrations of the 18 PAHs, which was constructed using an ordinary Kriging approach with log transformed data, clarified the regional variability and identified regional hot spots in the urban and industrial areas of Shanghai These hot spots all suffer from high PAH pollution, suggesting that local human activities (e g. vehicular traffic, petrochemical industry and coal combustion) may be the main contributors Coal or oil fired power plants and their locations seem to be a significant factor controlling the PAH concentrations in surface soil The higher molecular weight PAHs are often accumulated near pollution sources and are more heterogeneous in Shanghai soil, because they are less easily transported and biodegraded than 2 ring PAHs. The total concentrations are not correlated with soil total organic carbon We successfully applied hierarchical cluster analysis (HCA) and principal components analysis (PCA) based on a centered log ratio procedure to explore the characteristics and possible sources of soil PAHs. The high PAN contamination in the Shanghai surface soil is mainly attributed to the contribution of pyrogenic sources (vehicular traffic pollution and combustion of coal and biomass). Furthermore, we applied PAN percentages by ring number, isopleth maps of total concentrations of 18 PAHs and source diagnostic ratios of PAHs to help assign the pyrogenic sources in Shanghai soils Such map based approaches have only rarely been applied in investigations published in Organic Geochemistry.