In-situ time-resolved ATR-FTIR experiments were conducted to probe glyphosate adsorptiondesorption dynamics and mechanisms on K-birnessite and hausmannite thin films, with and without pre-sorbed BSA protein, at pH 4.6 and 7.2. Experimental details can be found in our previous work. Briefly, 5 μL of K-birnessite or hausmannite from 1.4 or 2.7 g L suspensions (respectively) were drop-cast on the diamond internal reflective element (diamond IRE; area ≈ 7.1 mm 2 ) of the ATR accessory (Pike GladiATR™; Pike Technologies Madison, WI) and dried under a gentle stream of nitrogen gas. Based on the specific surface area of Kbirnessite and hausmannite minerals (Table , SI), the Mn oxide films deposited on the diamond IRE had a similar total surface area (TSA ≈ 0.359 × 10 -3 m 2 ). At this low TSA, the IR signals of expected byproducts (e.g., glycine and AMPA) were negligible compared to that of glyphosate adsorbed at the surfaces. Preliminary experiments were conducted to optimize the concentration of influent glyphosate (C0) for in-situ ATR-FTIR experiments; a C0 = 2 mM was used to obtain high spectral signal-to-noise ratio (>10). The adsorption step (i.e., Phase 1; duration = 37 min) was followed by a desorption step (i.e., Phase 2; duration = 31 min) using 10 mM KCl supporting electrolyte solution at pH 4.6 and 7.2. FTIR spectra were collected over a scan range of 4400 -150 cm -1 with an average 96 scans and resolution of 8 cm -1 (probing interval = 0.8 min). BSA-Mn oxide associations were synthesized by running 7.5 μM BSA protein over pre-conditioned Mn oxide films on the diamond IRE until equilibrium (see Text S5