Table 5 Heavy metal concentrations (mg/kg) in parts of common cultivar of P. purpureum grown on palm oil mill effluent final discharge (treatment) and rain water (control), and comparison with the standards.

Al

2.10 ± 0.07^b

4.36 ± 0.07^a

0.21 ± 0.01^d

1.45 ± 0.04^c

0.21 ± 0.01^d

0.02 ± 0.01e-1^e

—

—

—

As

0.37 ± 0.02^a

0.16 ± 0.01^b

0.01 ± 0.05e-2^d

0.05 ± 0.02e-1^c

0.02 ± 0.01e-1^d

n.d.

0.02–7.00

1.10

—

Cd

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

0.10–2.40

1.50

0.02

Co

0.01 ± 0.02e-2

n.d.

n.d.

n.d.

n.d.

n.d.

0.05–0.50

—

—

Cr

n.d.

n.d.

n.d.

n.d.

n.d.

n.d.

0.20–1.00

20.00

1.30

Ni

0.03 ± 0.06e-2^c

0.04 ± 0.06e-2^b

0.02 ± 0.04e-3^d

0.06 ± 0.04e-2^a

n.d.

n.d.

1.00

1.00

10.00

Pb

0.04 ± 0.08e-2^a

0.03 ± 0.05e-2^b

n.d.

0.01 ± 0.02e-2^c

n.d.

n.d.

1.00–13.00

2.50

2.00