Author(s): A. Deletic; D. W. Orr
Linked Author(s):
Keywords: Urban Runoff; Field Measurements; Sediment; Particle Size; Heavy Metals; Nutrients
Abstract: Water quantity and quality of runoff from a small urban catchment were monitored continuously over a year, and 67 events were measured reliably. For a number of targeted storms, discreet samples of urban run-off, consisting of 115 water samples, were analysed for the following: suspended solids, particle size: Zn, Cu, Pb and Cd attached to sediment, and the dissolved species ▲, ▲, ▲, ▲, ▲, ▲, TOC and TC. The data was statistically analysed to investigate the physical and chemical properties of the runoff water quality. A strong seasonal influence was found: turbidity, sediment concentrations, conductivity and ionic concentrations were much higher in winter than in summer, due to de-icing salts and gritting of roads during cold weather. Particles in runoff were mainly below 100 um, with a mean diameter of d50=23 um. No significant correlation was found between particle size and flow rate. Of the particle size fractions analysed, attached heavy metal concentrations were greatest in the < 63 um fraction, and the relationships between these concentrations in runoff and the suspended sediment concentration of the < 63 um fraction were linear and highly significant. It was shown that turbidity measurement is not a reliable means for the monitoring of solids, but has some limited application for monitoring solids below 1 g/l. Continuous conductivity measurements could be used for monitoring of concentrations of total ionic dissolved pollutants, particularly the chloride ion, Cl-.
Year: 2003