Understanding urbanization development process and the associated PCBs concentration in urban soils - A genetic...

Area of Science:

• Environmental Science
• Urban Ecology
• Soil Chemistry

Background:

• Quantifying urbanization's environmental impact is crucial globally.
• Polychlorinated biphenyls (PCBs) are persistent organic pollutants of concern.

Purpose of the Study:

• To develop a method for quantifying the urbanization process.
• To assess the relationship between urbanization and PCB accumulation in soils.
• To identify critical urbanization thresholds for PCB contamination.

Main Methods:

• Established an in situ-controlled experimental system in Shanghai.
• Developed a Genetic Algorithm-Based Urbanization Index (GA-based UI) using landscape metrics.
• Employed correlation analysis, stepwise linear regression, random forest, and piecewise regression.

Main Results:

• Key variables for GA-based UI: road density, population change, industrial land use, and vegetation indices.
• Identified critical urbanization thresholds for PCB accumulation.
• PCB concentrations significantly increased within a GA-based UI range of 2.148-3.203 (22.36-26.74 km from urban center).

Conclusions:

• The GA-based UI effectively quantifies urbanization and its link to PCB soil contamination.
• A critical urbanization threshold exists where PCB accumulation intensifies.
• Findings provide a quantitative basis for urban planning and environmental management strategies.