where n is the number of heavy metals analyzed in the sample (i.e. n ¼ 7inthe
present study). RI can be classified into four levels: RI o 150: low risk, 150 r RI o 300:
moderate risk, 30 0 r RI o 60 0: considerable risk, and RI Z 60 0: very high risk.
Bioconcentration factor (BCF) and translocation factor (TF) were calculated to
estimate the ef fi ciency of a plant to accumulate heavy metals from sediment and to
translocate the heavy metals from its roots to its stems or leaves, respectively. BCF
and TF are calculated by the following formulas ( Wilson and Pyatt, 20 07; Zacchini
et al., 20 09 ):