DEGRADATION OF POLLUTANTS ON GROUND SURFACES OF PAVED URBAN AREAS

摘要

A lab-based experiment study was conducted to investigate the degradation of pollutants on pavement under the natural environment condition of dry days. In this experiment, waste water with high concentrations of pollutants was seeded on specially made concrete plots which represent impervious urban surfaces to avoid heterogeneity of pollutants dispersion on urban land surfaces. Simulated rainfall was employed to wash the pollutants off the plots after various antecedent dry periods (ADP). This can eliminate variability of unpredictable rainfall pattern. Pollutants degradation analysis was derived from the event mean concentrations (EMCs) of runoff collection obtained during the different ADPs ranged from 1 d - 10 d, consecutively with one-day gap intervals. From the experiments, significant temporal variation was found for BOD_5, TOG and TC. BOD_5 build-up was observed during the first 6-8 days of the dry period and degraded thereafter. TOG continually degrades over ADP while TSS, NO_3 and TPH showed insignificantly influenced by the length of ADP. No significant difference in the effect of degradation rates was observed between the thinner (2 cm) and thicker (5 cm) study plots. This suggested that the depth of impervious materials is not the influential factor when the surface has extremely low in both permeability and porosity.