Cations, including calcium, magnesium, potassium, sodium, copper, iron
, nickel and zinc, inhibited (up to 40%) extracellular binding and int
racellular uptake of cadmium by Lemna polyrhiza in solution culture, T
est plants showed a high capacity of extracellular cadmium binding whi
ch was competitively inhibited by copper, nickel and zinc; however, ca
lcium, magnesium and potassium caused non-competitive inhibition, Tron
and sodium increased K-m and decreased V-max, thereby causing mixed i
nhibition of extracellular binding, Intracellular cadmium uptake displ
ayed Michaelis-Menten kinetics, It was competitively inhibited by calc
ium, magnesium, iron, nickel and zinc. Monovalent cations (sodium and
potassium) caused non-competitive and copper caused mixed inhibition o
f intracellular cadmium uptake, Thus, high levels of cations and metal
s in the external environment should be expected to lower the cadmium
accumulation efficiency of L. polyrhiza.