Spatial Distribution, Potential Sources, and Health Risk of Polycyclic Aromatic Hydrocarbons (PAHs) in the Surface Soils under Different Land-Use Covers of Shanxi Province, North China

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are widespread in the environment and pose a serious threat to the soil ecosystem. In order to better understand the health risks for residents exposed to PAH-contaminated soil, 173 surface soil samples were collected in Shanxi Province, China, to detect the levels of 16 priority PAHs. The spatial distribution patterns of PAHs were explored using interpolation and spatial clustering analysis, and the probable sources of soil PAHs were identified for different land-use covers. The results indicate that the soil Σ16 PAH concentration ranged from 22.12 to 1337.82 ng g^-1, with a mean of 224.21 ng g^-1. The soils were weakly to moderately contaminated by high molecular weight PAHs (3-5 ring) and the Taiyuan-Linfen Basin was the most polluted areas. In addition, the concentration of soil PAHs on construction land was higher than that on other land-use covers. Key sources of soil PAHs were related to industrial activities dominated by coal burning, coking, and heavy traffic. Based on the exposure risk assessment of PAHs, more than 10% of the area was revealed to be likely to suffer from high carcinogenic risks for children. The study maps the high-risk distribution of soil PAHs in Shanxi Province and provides PAH pollution reduction strategies for policy makers to prevent adverse health risks to residents.

Keywords: GIS; PAHs; carcinogenic risk; land-use management; spatial pattern.

Figure 1

Location of (a) study area and (b) sampling sites under various land-use covers.

Figure 2

Proportion of individual PAHs (a) and PAHs with different ring numbers (b) in the soil samples. carcinogenic PAHs. Naphthalene (Nap); acenaphthylene (Acy); acenaphthene (Ace); fluorene (Flu); phenanthrene (Phe); anthracene (Ant); fluoranthene (Fla); pyrene (Pyr); benz[a] anthracene (Baa); chrysene (Chr); benzo[b] fluoranthene (Bbf); benzo[k] fluoranthene (Bkf); benzo[a] pyrene (Bap); indeno[1,2,3-cd] pyrene (Inp); dibenzo[ah]anthracene (Daa); and benzo[ghi] perylene (Bgp).

Figure 3

Spatial distribution pattern of soil ∑16 PAHs and PAHs with different ring numbers in Shanxi Province. (a) 2-ring PAHs; (b), 3-ring PAHs; (c) 4-ring PAHs; (d) 5-ring PAHs; (e) 6-ring PAHs; (f) ∑16 PAHs; (g) location of Taiyuan–Linfen Basin.

Figure 4

Clustering and outlier analysis of soil ∑16 PAHs and PAHs with different ring numbers in Shanxi Province, using the local indicators of spatial association method (LISA). (a) 2-ring PAHs; (b) 3-ring PAHs; (c) 4-ring PAHs; (d) 5-ring PAHs; (e) 6-ring PAHs; (f) ∑16 PAHs; (g) schematic diagram of administrative division of Shanxi Province.

Figure 5

Boxplot of soil PAHs with different ring numbers (a–e) and ∑16 PAHs (f) under different land-use covers in Shanxi Province.

Figure 6

Stacked histogram of PAHs with different ring numbers (a) and histogram of 16 individual PAHs (b–e) under different land-use covers in Shanxi Province.

Figure 7

Source profiles and contribution of soil PAHs under farmland (a), forest (b), grassland (c), construction land (d), and all covers of land-use (e) obtained by PMF (positive matrix factorization).

Figure 8

Spatial patterns and composition proportion of risk level of children (a), youths (b), and adults (c) in soil PAHs.