Selectivity for the AMPA pathway, as indicated by SAMPA (Table ), increased in the presence of BSA on K-birnessite at pH 4.6 (0.43 to 0.78) and 7.2 (0.23 to 0.47). However, the presence of BSA on hausmannite did not have this effect, likely due to its greater standard reduction potential (E 0 ) that results in lower catalytic oxidation activity (E 0 K-birnessite ≈ 1.23 V and E 0 hausmannite ≈ 1.83 V). With increasing pH, in the absence or presence of BSA, corresponding SAMPA values decreased and less AMPA was measured in collected effluents while glycine remained the dominant byproduct (Figure and Table and). Lasty, K-birnessite showed and Table ) with measured soluble Mn in the effluents reveals that dissolution of Mn oxide by glyphosate is predominately due to chelation dissolution mechanism at pH 4.6 (Figure ). And this reaction is mainly governed by pH since no dissolved Mn was detected in collected effluents at pH 7.2. Reductive dissolution of Mn oxides, specially hausmannite, is a less significant mechanism, as the measured dissolved Mn does not show 1:1