Contamination of waters all over the world by heavy metals continues to present a serious
threat to the environment and human health. Many heavy metals are toxic even at low
concentrations and often accumulate throughout the food chain (An et al. 2001). The main
heavy metals that are found in dissolved form in stormwater are Zn, Cu and cadmium (Cd)
(Minton, 2005). In New Zealand, the Zn is thought to primarily come from galvanized roofing
material and vehicle tyres, while the Cu originates from vehicle brake linings.