the divalent cations , ca , sr , ba at less than or equal to 50 microm , zn , mn , cd at greater than or equal to 50-100 microm , and mg at greater than or equal to 1.0 mm , as well as the trivalent cation la at greater than or equal to 15 microm , all increase fmepp exponentially to greater than or equal to 100-200 s-1 over several minutes time .
C0007448
divalent cations
C0007447
cation