摘要
Urbanization may cause increased exposure levels to polycyclic aromatic hydrocarbons(PAHs) and associated health risks for over half of the world's population living in cities,but little evidence has shown a direct spatial relationship between urbanization and soil PAH pollution.Based on the monitored PAH concentrations in 188 topsoil(0-5 cm) samples in Shenzhen,the most rapidly developing city in China,in recent decades,we applied geographical demarcation to determine the occurrences,source apportionments,and spatial ecological risks of soil PAHs across five zones of varying urban densities.Mean concentrations of the 16 US Environmental Protection Agency(EPA) priority PAHs(Σ_(16)PAHs) and the 7 carcinogenic PAHs(Σ_7CarPAHs) both followed the order:Zone D(60%-80%constructive land density(CLD)) > Zone E(80%-100%CLD) > Zone C(40%-60%CLD) > Zone B(20%-40%CLD) > Zone A(0%-20%CLD),suggesting that the highest PAH levels occurred in the suburban-urban center transitional zone(Zone D) rather than the urban center zone(Zone E) in Shenzhen.There were significant correlations of Σ_(16)PAHs to TOC and sampling altitude across all samples but not within highly-urbanized regions(Zones D and E),implying a considerable disturbance of urbanization to the soil PAH pool.Source apportionments suggested that soil PAHs of all zones were mainly derived from fossil fuel combustion,with Zone E showing the highest contribution from oil sources among different zones.Spatial ecological risk analysis showed that the contaminated area(467 km^2;23.9%of total area;toxic equivalency quotients > 33 ng g^(-1)) had a higher contribution from the highly-urbanized regions(Zones D and E) than the uncontaminated area(42.3%vs.18.1%).Overall,our study highlighted a strong spatial relationship between urbanization and soil PAH pollution.
Urbanization may cause increased exposure levels to polycyclic aromatic hydrocarbons (PAHs) and associated health risks for over half of the world's population living in cities, but little evidence has shown a direct spatial relationship between urbanization and soil PAH pollution. Based on the monitored PAH concentrations in 188 topsoil (0-5 cm) samples in Shenzhen, the most rapidly developing city in China, in recent decades, we applied geographical demarcation to determine the occurrences, source apportionments, and spatial ecological risks of soil PAHs across five zones of varying urban densities. Mean concentrations of the 16 US Environmental Protection Agency (EPA) priority PAHs (∑16PAHs) and the 7 carcinogenic PAHs (2E7CarPAHs) both followed the order: Zone D (60%-80% constructive land density (CLD)) 〉 Zone E (80%-100% CLD) 〉 Zone C (40%-60% CLD) 〉 Zone B (20%-40% CLD) 〉 Zone A (0%-20% CLD), suggesting that the highest PAH levels occurred in the suburban-urban center transitional zone (Zone D) rather than the urban center zone (Zone E) in Shenzhen. There were significant correlations of ∑16PAHs to TOC and sampling altitude across all samples but not within highly-urbanized regions (Zones D and E), implying a considerable disturbance of urbanization to the soil PAH pool. Source apportionments suggested that soil PAHs of all zones were mainly derived from fossil fuel combustion, with Zone E showing the highest contribution from oil sources among different zones. Spatial ecological risk analysis showed that the contaminated area (467 km2; 23.9% of total area; toxic equivalency quotients 〉 33 ng g^-1) had a higher contribution from the highly-urbanized regions (Zones D and E) than the uncontaminated area (42.3% vs. 18.1%). Overall, our study highlighted a strong spatial relationship between urbanization and soil PAH pollution.
基金
supported by the "Laboratory Capacity Building Project" of Shenzhen Municipal Science and Technology Innovation Council, China (No. ZDSY20120614145024623)
the State Key Program of National Natural Science of China (No. 41230634)
关键词
多环芳烃
表层土壤
城市密度
和空间
贡献率
深圳
风险评估
事件
altitude, carcinogenic PAHs, soil PAH pollution, total organic C, toxic equivalency quotient, urbanization, US EPA priority PAH