Fig. 3. Chloride breakthrough curves (BTCs) for undisturbed soil columns: (a) as a function of cumulative drainage, and (b) as a function of time (Exp. 1). The BTCs rising limbs for sand columns: (c) as a function of cumulative drainage, and (d) as a function of time. The BTCs falling limbs for sand columns: (e) as a function of cumulative drainage, and (f) as a function of time (Exp. 2). The BTCs for sand columns with chloride applied on the surface of the column: (g) as a function of cumulative drainage, and (h) as a function of time (Exp. 3). For (a) and (b), S represents the point where the rain with Cl was switched to regular acid rain. For (e) and (f), the y axis indicates the time after switching to the regular rain. C1 and C2 refer to Columns 1 and 2, respectively.