Emerging PAHs in urban soils: Concentrations, bioaccessibility, and spatial distribution.

Area of Science:

• Environmental Chemistry
• Soil Science
• Urban Ecology

Background:

• Polycyclic aromatic hydrocarbons (PAHs) are widespread organic pollutants, with soils acting as a primary reservoir.
• Understanding the distribution and impact of emerging PAHs is crucial for accurate environmental risk assessment.

Purpose of the Study:

• To determine concentrations, bioaccessibility, and spatial distribution of six emerging PAHs in Orlando and Tampa urban soils.
• To compare the levels of emerging carcinogenic PAHs (3cPAHs) with U.S. EPA priority carcinogenic PAHs (7cPAHs).
• To evaluate the significance of emerging PAHs in urban soil risk assessment.

Main Methods:

• Analysis of 3 carcinogenic (anthanthrene, 7H-benzo[c]fluorene, dibenzo[a,l]pyrene) and 3 non-carcinogenic PAHs.
• Quantification using benzo[a]pyrene-equivalent concentrations.
• Spatial distribution mapping using ArcGIS.
• Bioaccessibility assessment via n-butanol extraction.

Main Results:

• Emerging 3cPAHs concentrations were 6-16 times higher than ∑7cPAHs in both cities.
• Higher ∑3cPAHs concentrations were observed in commercial, business, and heavy-traffic areas.
• Bioaccessibility of these emerging PAHs was low, averaging 3.4-7.4% in both urban soils.

Conclusions:

• Emerging carcinogenic PAHs significantly contribute to the overall PAH burden in urban soils.
• Their high relative potency necessitates their inclusion in PAH risk assessments.
• Considering emerging PAHs and their bioaccessibility is vital for accurate urban soil contamination risk evaluation.