Table 1.

List of concentrations of main heavy metals detected in the 15d-DPFs leachates (μg/L). Standard deviation analysis is based on triplicate tests. N.D represents “non-detected”.

Sample	Cd	Co	Cr	Cu	Mn	Ni	Pb	Sr	Ti	Zn
Control	0.3	N.D	N.D	0.2	0.1	N.D	0.1	N.D	N.D	0.1
Mask 1	1.2 ± 0.1	7.3 ± 0.1	0.8 ± 0.1	6.6 ± 0.1	2.9 ± 0.1	2.8 ± 0.1	1.3 ± 0.1	13.1 ± 1.5	7.7 ± 1.0	13.9 ± 3.6
Mask 2	0.6 ± 0.1	5.6 ± 0.5	0.8 ± 0.3	4.7 ± 0.8	0.9 ± 0.1	1.1 ± 0.3	0.8 ± 0.2	10.2 ± 1.6	5.2 ± 1.3	10.3 ± 1.6
Mask 3	1.0 ± 0.3	5.8 ± 0.2	0.7 ± 0.1	8.3 ± 1.1	2.1 ± 0.9	1.3 ± 0.6	1.1 ± 0.3	14.4 ± 1.1	7.8 ± 2.3	15.6 ± 1.5
Mask 4	N.D	7.2 ± 0.9	0.8 ± 0.3	7.7 ± 0.5	1.6 ± 0.6	1.9 ± 0.5	0.7 ± 0.2	10.3 ± 2.7	9.2 ± 2.7	12.7 ± 2.6
Mask 5	N.D	7.6 ± 0.6	0.4 ± 0.1	7.3 ± 0.7	1.4 ± 0.6	0.7 ± 0.3	0.7 ± 0.2	11.6 ± 2.3	6.6 ± 2.5	10.8 ± 3.4
Mask 6	1.3 ± 0.3	8.0 ± 0.7	N.D	6.5 ± 0.3	2.0 ± 0.3	0.9 ± 0.4	0.9 ± 0.2	12.5 ± 1.6	6.9 ± 1.3	17.7 ± 2.6
Mask 7	0.8 ± 0.1	3.1 ± 1.0	N.D	1.2 ± 0.4	N.D	0.8 ± 0.2	N.D	0.5 ± 0.1	0.9 ± 0.2	10.2 ± 1.6
Mask 8	N.D	6.4 ± 2.1	N.D	0.9 ± 0.4	N.D	0.5 ± 0.1	N.D	0.8 ± 0.2	0.7 ± 0.3	9.3 ± 2.2