Characterizing nitrogen deposited on urban road surfaces: Implication for stormwater runoff pollution control

Area of Science:

• Environmental Science
• Urban Hydrology
• Pollution Control

Background:

• Nitrogen (N) is a significant pollutant in urban road runoff.
• Understanding N deposition forms and loads is crucial for effective stormwater management.
• Roads act as a pathway for nitrogen pollution into urban water bodies.

Purpose of the Study:

• To characterize nitrogen deposition forms and loads on urban roads in Guangzhou, China.
• To investigate the influence of land-use types and traffic factors on nitrogen build-up.
• To estimate nitrogen pollution hotspots and total nitrogen (TN) flux using an artificial neural network (ANN) model.

Main Methods:

• Analysis of dissolved and particulate nitrogen forms on urban road surfaces.
• Correlation analysis with land-use types and traffic factors.
• Application of an ANN model for hotspot classification and TN flux estimation.

Main Results:

• Particulate organic nitrogen is the predominant form of N on urban roads.
• Residential areas (RA) and urban villages (UV) exhibit higher TN build-up loads.
• Land use was found to have a greater impact on nitrogen build-up than traffic factors.
• RA and UV were identified as nitrogen pollution hotspots.
• The estimated annual TN flux from roads in Guangzhou is 3.35 × 10^5 g, representing 19% of the city's total urban domestic discharge.

Conclusions:

• Urban road surfaces contribute significantly to nitrogen pollution in receiving waters.
• Land-use planning, particularly in RA and UV, is critical for mitigating nitrogen runoff.
• The study provides valuable data for developing targeted pollution control strategies for urban stormwater runoff.