Characterising metal build-up on urban road surfaces

Abstract

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.

An Investigation of the Relationships between Rainfall Conditions and Pollutant Wash-Off from the Paved Road

“…It is noteworthy that the results were not consistent with previous findings stating that the pollutant wash-off has a great impact on pollutant load present in runoff, while pollutant build-up has only a minor effect [8,[20][21][22]. The possible reason for these different observations could be related to the specific size of accumulated solids.…”

“…Vaze and Chiew [8] found that particles less than 300 μm were predominant in their place of study; Egodawatta and Goonetilleke [20] noted that particles finer than 100 μm had the largest fraction on studied pavements, and Wijesiri et al [22] studied that the greatest wash-off load was composed mainly of particle size fractions less than 150 μm. Among these studies, the predominant particles were relatively coarser than those of the present study.…”

The sources, impact and management of car park runoff pollution: A review

“…Typically the values of b are negative (Egodawatta et al, 2013) indicating that during dry conditions the build-up process decreases gradually after an initial high accumulation and eventually reaches an almost constant value after 14 days. This predicted enhanced early build-up combined with the amounts of material which can potentially be deposited on surfaces similar to those found in car parks indicate the need for regular cleaning to ensure the effective removal of pollutants, particularly those associated with coarse solids.…”

“…A wide range of mathematical models including linear, power, exponential and MichaelisMenton functions have been used to describe the temporal build-up process (Huber and Dickinson 1988). However, the most widely employed predictive relationships for urban surfaces are the exponential (Bertrand-Krajewski et al, 1993;Charbeneau and Barrett, 1998;Deletic et al, 1997;Shaheen, 1975) and power functions (Ball et al, 1998;Egodawatta et al, 2013).…”

Is the wash-off process of road-deposited sediment source limited or transport limited?

“…However, only limited actual direct measurements of RDS build-up are available, and it has instead been inferred from the measurements of RDS wash-off (Pitt et al, 2004;Shaw et al, 2006;Vaze and Chiew, 2002). In recent years, a few studies have revealed that RDS build-up is influenced by antecedent dry periods, rainfall events and street sweeping (Deletic and Orr, 2005;Egodawatta et al, 2013;Shen et al, 2016;Tian et al, 2009).…”