Spatial distribution and sources of PAHs in topsoil in the Beiyun River Basin (Beijing section)

Organic pollution of polycyclic aromatic hydrocarbons (PAHs) in topsoil has threatened human health and ecological environment. In order to understand the distribution and pollution characteristics of PAHs in topsoil in the Beiyun River Basin in Beijing, an investigation is carried out to examine the contents, distribution trends, spatial distribution and pollution sources of 16 optimal PAHs in topsoil of the study area by means of multivariate statistical methods including the Kriging interpolation, principal component analysis-multiple linear regression and the concentration ratio among certain components. The results are as follows (1) all 16 PAHs are detected, and most of them are high loop PAHs (4−6 rings). The total contents of PAHs in topsoil range from 10.5 to 19466.5 μg/kg, about 29.63% of the samples are polluted in the study area. (2) The PAHs contents in topsoil show a trend of higher in the middle and lower at ends in both east-west and south-north direction. In terms of spatial distribution, the PAHs contents in topsoil are higher in the northern region and the central urban area, while the PAHs contents are lower in other areas. Due to the accumulation of PAHs caused by human activities at some points, point source pollution or local pollution exist. (3)The ratio of specific PAHs components and principal component analysis indicate that the sources of 16 PAHs in the study area are mainly coal, biomass combustion and traffic combustion. Multiple linear regression shows that the contribution rates of the two are 89% and 11% respectively. The research results can provide strong support for pollution prevention and control, land quality evaluation and territorial space planning in the study area.