Fig. 5
From: Low presence of potentially toxic elements in Singapore urban garden soils
Plots of copper (Cu) versus zinc (Zn) concentrations for: (a) garden (G), park (P) and woodland (W) sites investigated in this study (n = 10 samples each); and (b) various soils, road dust, and fly ash in Singapore (from Table 1), along with median values from this study. Background (BKG), Threshold Risk Concentrations (TRC), Potential Risk Concentrations (PRC), and Elevated Risk Concentrations (ERC) are listed in Table 4 (top panel). In panel a, all thirty values for each land use type are shown. In panel b, element concentrations beyond the ERC thresholds are considered to have a substantial anthropogenic enrichment (as in the case of fly ash and most road dust samples)