Insights into atrazine degradation by thermally activated persulfate: Evidence from dual C–H isotope analysis and DFT simulations

•CSIA was effective to in situ analyze radical contributions on ATZ degradation by heat-activated PS.•ATZ can be degraded by heat-activated PS with high removal efficiency at pH 4–10.•Changes of δ13C and δ2H during ATZ degradation followed Rayleigh equation well.•The εC values were 1.58‰ at pH 4 and 0.65‰ at pH 7 for SO4– -dominated oxidation.•Contributions of SO4- by heat-activated PS were ∼ 100 % and 83.9 % at pH 4 and 7.