Comparative study on anthropogenic impacts on soil PAHs: Accumulation and source apportionment in tourist and industrial cities in Hebei Province, China

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous organic contaminants in urban soils. The accumulation and source identifications of PAHs within a city have been frequently studied. However, impacts of urbanization development modes on PAHs accumulation patterns by taking a city as a whole have been seldom reported. Four cities with two development modes in Hebei province, Chengde and Zhangjiakou (tourist cities) and Handan and Tangshan (industrial cities), were selected. The concentrations of 16 priority PAHs in soils in the study areas were investigated. The results showed that the average concentrations of Sigma(16)PAHs in Handan (2517 mu g/kg) and Tangshan (2256 mu g/kg) were more than twice of those in Chengde (696 mu g/kg) and Zhangjiakou (926 mu g/kg) approximately. Lines of evidence, provided by a combination of diagnostic ratios, pairwise correlation, and PMF methods, revealed that the dominant sources of PAHs in either city were industrial emission, vehicle emission, and petrogenic/biogenic process but with different proportions. Linear fittings based on Bayesian kernel machine regression analysis (BKMR) were constructed to illustrate the impact of industrialization on PAHs accumulation. The probability of excessing the 10 % (376 mu g/kg) and 50 % (1138 mu g/kg) of current & sum;(16)PAHs would be higher than 90 % given the gross industrial production per unit area >5.00 x 10(6) and 20.5 x 10(6) CNY/km(2), respectively. The proposed threshold values of industrialization are of significance for determining industrial structure and proportion in urban management.