Vehicular traffic on road asphalt generates a variety of inorganic and organic contaminants. These accumulate on the road surface in quantities that depend on the traffic and road conditions. During rainfall events, they are washed from the road surface and make a major contribution to stormwater pollution.
This road runoff contains suspended and dissolved inorganic and organic contaminants, and is a problem, particularly in urban areas, because of its potential chronic toxicity for aquatic species in the recipient waterbodies.
This project, carried out in 2001, was to investigate contaminants found in New Zealand road runoff, and to characterise the components at source. It was also to determine how the relative concentrations, total load, and characteristics change with the frequency and intensity of rainfall events.
A sampling system consisting of a 6700 ISCO automatic sampler was set up to sample continuously from the drain leading from a road roundabout on the outskirts of Hamilton City. Samples from six rainfall events were collected between 26/1/2001 and 28/3/2001 at programmed intervals over the first 2 hours of precipitation.
Conductivity, pH, dissolved oxygen (DO), temperature, flowrate and rainfall intensity were monitored continuously.
Analysis of Cd, Cr, Cu, Fe, Ni, Pb and Zn was performed on each of the 1000mL samples using inductively coupled plasma optical emission spectroscopy (ICP-OES).
The remaining volume (c.900mL) was liquid/liquid extracted and analysed by selected ion monitoring gas chromatography/mass spectrometry (SIM GC/MS) for pyrene, fluoranthene, phenanthrene and benzo(a)pyrene.
Keywords: contaminants, environment, heavy metals, inorganic compounds, modelling, New Zealand, organic compounds, PAHs, pavements, pollution, rainfall, roads, runoff, sampling, traffic, treatments, water quality