[Experimental study on rainfall-runoff pollutant reduction by urban green space].

Area of Science:

• Environmental Engineering
• Water Quality Management
• Urban Hydrology

Background:

• Non-point source pollution from urban rainfall-runoff significantly contaminates surface water and degrades ecosystems.
• Effective strategies are needed to mitigate these impacts and improve urban water quality.

Purpose of the Study:

• To experimentally assess the pollution reduction effectiveness of green spaces using a soil aquifer treatment system.
• To analyze the influence of land cover, influent concentration, soil depth, hydraulic loading rate, and residence time on pollution removal.

Main Methods:

• Construction and operation of a soil aquifer treatment system.
• Experimental analysis of pollution reduction for chemical oxygen demand (COD), ammonium (NH4+ -N), and total phosphorus (TP).
• Evaluation of various influencing factors including land cover and hydraulic loading rates.

Main Results:

• Green spaces demonstrated a stable ability to reduce COD, NH4+ -N, and TP concentrations.
• Pollution reduction rates for COD, NH4+ -N, and TP ranged from 33.41%-37.14%, 58.74%-61.49%, and 63.65%-67.08%, respectively.
• Pollution reduction primarily occurred in the upper 50-70 cm of the green space soil.

Conclusions:

• Green spaces are effective in reducing urban rainfall-runoff pollution.
• Land cover effects were limited by oxygen and hydraulic residence time.
• The system maintained 50%-60% comprehensive pollution reduction ability even with increased influent concentrations.