335 Figure 1 - Conceptual model of monthly infiltration, reaction, and drainage under climatic pulses in a filled pit The validation of depletion rates was performed by comparing the simulated response with experimental results from moisture cells (accelerated test) under a standard protocol for weathering and leachate generation. Based on time series of pH, sulfate, and metals in effluents, empirical Langmuir and Weibull models on cumulative release/depletion were adjusted, and their characteristic constants were compared with the effective rates implicit in the kinetics implemented in PHREEQC (depletion of remaining moles and production of dissolved species). 3. RESULTS The results were analyzed based on monthly outputs aggregated on an annual scale, reporting for each year the minimum, maximum, and average values, as well as the “band” (Max-Min) as a measure of intra-annual variability associated with hydrological pulses. Two configurations were evaluated: a scenario with transient hydroclimatic forcing (scenario 1; period 2026-2100) and a scenario with stationary average precipitation (scenario 2; period 20262125). Figure 2 summarizes pH, sulfate, iron, and arsenic for both scenarios, showing the annual average (line) and variability (shading/band). In both scenarios, pH remained in the moderate acidity range (4.4-4.7), with a slight downward trend over time. In scenario 1, the annual average pH decreased from 4.654 (2026) to 4.563 (2100), a total reduction of 0.091 units, while in scenario 2 it decreased from 4.662 (2026) to 4.500 (2125), a total reduction of 0.161 units. The main difference was not the average, but the variability: scenario 1 had a median annual pH range of 0.115, with years of high With O₂ penetration No O₂ penetration Precipitation Drainag p r ont i ulat d inal lu nt ualit in t tailings pond p r ont r cipitation o s condar in ral p as s und r t n c ical conditions Infiltration according to recharge rate (%)
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