Figure 7A shows the Fourier-transformed k3-weighted EXAFS oscillations into R space of Fe K edge in Fe-containing sample, and Figure 7B shows the corresponding k3·χ(k) in the k range of 2.0−12.0 Å−1. Also, because of the large coordination shells of Fe−O and Fe−Fe in all samples, similar to those in the Mn K-edge case, the Fe−As coordination shell with a small scattering effect of photoelectrons was not included in the curve-fitting step either. From Figure 7B, we can see that good curve-fitting degrees can be obtained between experimental data and theoretical results, and the curve-fitted data are presented in SI Table 3 of the Supporting Information. Before and after As(III) or As(V) adsorption, no obvious changes in coordination numbers and bond distances of the first and second coordination shells were observed, suggesting that the local structure of the FeOOH phase could be maintained stable in the As adsorption process.