C-13 NMR spectra showed that peroxymonocarbonate (HCO4-) was generated in the NaHCO3-activated H2O2 solution and pH was a key factor in its production. A cycle for the bicarbonate anion was proposed as HCO3- -> (HCO3)-H-center dot -> (CO2)(2)* CO2(aq) -> HCO4- (H2CO4) -> HCO3- ((HCO3)-H-center dot) basing on the results of NMR, electron paramagnetic resonance, chemiluminescence analysis. In this cycle, (CO2)(2)* was the key intermediate and (CO2)(2)* -> 2CO(2) +hv was the rate controlling step. Thioanisole and paraoxon, the simulants of sulfur mustard gas and nerve gas, respectively, were efficiently decontaminated by the NaHCO3-activated H2O2 solution. While HCO4- was the primary oxidant for the oxidation of thioanisole, O-center dot(2)- generated during the decomposition of HCO4- or H2O2 led to the secondary oxidation of the sulfide. Paraoxon was degraded in the NaHCO3-activated H2O2 solution via nucleophilic substitution by OOH- and OH-, and the degradation rate increased exponentially with increasing pH. Alkali metal ions had a catalytic effect on the degradation of paraoxon. Mustard gas and soman degraded efficiently into nontoxic products in NaHCO3-activated H2O2, A pH range of 9-10 was found to be optimum for the broad-spectrum decontamination of chemical warfare agents and other eco-toxicants using NaHCO3-activated H2O2. (C) 2017 Published by Elsevier B.V.