Fig. 2. Observed (discrete points) N₂H⁺₅ and Ca²⁺ breakthrough curves (BTCs) in effluent from an Arredondo Ap soil column injected with a pulse of medium hydrazinium concentration (5.64 mol_c m^-3). Simulated BTCs with (smooth lines) and without (broken lines) chemisorption of exchange-phase N₂H⁺₅ are given.