Polycyclic aromatic hydrocarbons in soils of an industrial area of China: multivariate analyses and geostatistics

Tianjin Bin Hai New Area (BHNA) is the third largest economic zone in China. This is an older industrial area that has been developing rapidly but with many historic sources of contamination. The concentrations of 16 individual polycyclic aromatic hydrocarbons (PAHs) listed for priority control by the US EPA were quantified in 105 surface soil samples by the use of gas chromatography mass spectrometry (GC/MS). Multivariate statistical methods were used to characterise the mixtures and make comparisons in the patterns among areas. Concentrations varied among areas, ranging from moderate to relatively high. The coefficients of determination between concentrations of individual PAHs and total concentration of PAH (Sigma PAH) increased with the number of rings. The first three factors from the principal component analysis (PCA) explained 81.6% of the total variation, while ten higher molecular weight (HMW) PAHs' loadings for factor 1 accounted for 51.0%. Based on the patterns of relative loading proportions of individual PAHs calculated by PCA, the primary sources were coal combustion, traffic emissions including gasoline, diesel oil, and the burning of natural gas. The spatial distribution of concentrations of fluorene had a poor spatial autocorrelation in the study area. The sites with the greatest potential risk due to exposure to PAHs were mainly distributed around the chemical industry parks.