“…For the urbanisation categories and clrCa, the Tukey honest significance difference pairwise test showed a significant difference (p < .0001) between all OLD and NEW categories and the NURB and OLD categories but not between the NURB and NEW categories (p = .1). Thorpe and Harrison (2008), Pant and Harrison (2013) and Wang et al (2017) summarise the sources of elements associated with road traffic (Cu, Zn, Pb, Cd, Cr, Co, Ni, As, Ba, Sb, Mn, V, Pt, and Rh) of which the most dominant historically is reported to be Pb from leaded petrol/gasoline. Subsidiary amounts of Ba, Cu, Fe, Sb, Zn, Cd, Co, and Cr come from brake linings (of which Cu is the most abundant) and tyres (only Zn significantly exceeds crustal abundance; Thorpe and Harrison, 2008).…”