United State National Oceanic Atmospheric Administration's Effect Range Low (ERL) and Effects Range Median (ERM) concentrations for the studied metals (values are in mg/kg dry weight).

Table 2: United State National Oceanic Atmospheric Administration's Effect Range Low (ERL) and Effects Range Median (ERM) concentrations for the studied metals (values are in mg/kg dry weight) (after [18,19]).

Metals	ERL (mg/kg)	ERM (mg/kg)
Cd	1.2	9.6
Cu	34	270
Pb	46.7	218
Zn	150	410
Mn	***	***
Ni	20.9	51.6
Fe	***	***

N.B: *** = Values not given.