Table 3.

Concentrations of heavy metals in the different size fractions of urban, motorway, and mountain road dusts

Mean concentration in fractions	Weight %	Cr	Zn	Fe	Pb	Ni	Cu	Ti	Sr	Ba	Se	Cd	Pd
Motorway dust mg/kg (n = 3)
<20 μm	0.86	182	1829	51,907	456	109	287	2678	132	533	0.157	0.912	0.095
20–56 μm	1.58	132	1609	50,899	362	98.2	209	2289	129	302	0.109	0.659	0.087
56–90 μm	2.86	112	1390	46,758	326	87	120	1198	113	256	0.043	0.584	0.029
90–250 μm	25.72	109	593	30,145	213	49.9	93.2	399	108	99.8	0.056	0.245	0.023
>250 μm	68.98	111	730	19,940	138	48.2	78.2	422	109	107	0.053	0.098	0.019
Urban road dust mg/kg (n = 3)
<20 μma	0.94	219	2565	62,897	789	87.9	389	863	129	509	0.161	1.094	0.101
20–56 μm	2.98	198	2267	54,389	743	89.4	353	809	98.2	312	0.086	0.78	0.089
56–90 μm	6.87	169	1768	50,980	569	76.5	189	609	95.3	267	0.034	0.56	0.044
90–250 μm	32.98	222	1879	41,434	309	28.4	103	189	66.5	109	0.029	0.218	0.034
>250 μm	56.23	87.9	946	20,390	387	22.7	89	176	89.4	201	0.022	0.081	0.022
Mountain road dust mg/kg (n = 1)
20–56 μm	0.54	51.7	559	14,098	188	54.8	209	498	87.3	161	0.032	0.192	0.016
56–90 μm	1.41	48.3	396	13,077	40.9	42.2	86.4	308	78.1	113	0.019	0.147	0.015
90–250 μm	28.31	23.9	221	12,900	47.6	28.1	35.3	297	79.4	79.9	0.028	0.111	0.013
>250 μm	69.74	38.9	198	10,890	12.4	23.3	33.9	288	134	89.9	b.d.l.	0.198	0.015

b.d.l. below detection limit

^a n = 1