Characterising metal build-up on urban road surfaces

Reliable approaches for predicting pollutant build-up are essential for accurate urban stormwater quality modelling. Based on the in-depth investigation of metal build-up on residential road surfaces, this paper presents empirical models for predicting metal loads on these surfaces. The study investigated metals commonly present in the urban environment. Analysis undertaken found that the build-up process for metals primarily originating from anthropogenic (copper and zinc) and geogenic (aluminium, calcium, iron and manganese) sources were different. Chromium and nickel were below detection limits. Lead was primarily associated with geogenic sources, but also exhibited a significant relationship with anthropogenic sources. The empirical prediction models developed were validated using an independent data set and found to have relative prediction errors of 12–50%, which is generally acceptable for complex systems such as urban road surfaces. Also, the predicted values were very close to the observed values and well within 95% prediction interval.

► Geogenic metals such as Al, Ca, Fe and Mn have similar build-up process.
► Similarly, anthropogenic metals such as Cu and Zn have similar build-up process.
► Build-up process for geogenic metals is different to that for anthropogenic metals.
► Lead is mainly from geogenic sources, but also related to anthropogenic sources.
► Reliable empirical prediction models developed for metal build-up on road surfaces.