In an explicit water environment (Fig. ), the physisorption mechanism prevails for MMA III because electron densities at the BCP of intermolecular interactions are in the range of 0.02-0.01 e/Bohr 3 , which is related to electrostatic interactions. A similar trend is observed for the anionic DMA V forms (Fig. ), where the chemisorption prevails, as noted from the high electron density values at the BCP of P-O bond (ρi=0.113 e/Bohr 3 ) with a slight change related to the implicit solvent model (ρi=0.144 e/Bohr 3 ). Consequently, only the monomethylated trivalent species of arsenic will have relatively higher mobility than the rest of the methylarsenicals. Thus, it could be predicted that the mobility in water decreases accordingly to the electron densities at the BCP in the following order: