Figure 1. Bioaccessibility of As in the gastric (A) and intestinal (B) phase after addition of different dietary components before (U) and after (S) FeSO4 stabilization. Data are presented as the mean ± standard deviation (S.D.) of the three experimental groups. ANOVA analysis reveals the statistical differences between the stabilization treatments and dietary addition groups. An asterisk (*) indicates significant difference between the different dietary addition groups (pp values is given in Table S4. Figure 2. Bioaccessibility of Zn in the gastric (A) and intestinal (B) phases after addition of different dietary components before (U) and after (S) FeSO4 stabilization. Data are presented as the mean ± standard deviation (S.D.) of the three experimental groups. ANOVA analysis reveals the statistical differences between the stabilization treatments and dietary addition groups. An asterisk (*) indicates significant difference between the different dietary addition groups (pp values is given in Table S4. Figure 3. Transformation of As in the gastric and intestinal phases after addition of different dietary components before and after FeSO4 stabilization. Data are presented as the mean ± standard deviation (S.D.) of the three experimental groups. ANOVA analysis reveals the statistical differences between the stabilization treatments and dietary addition groups of different As fractions. Summary of statistical information including p values is given in Table S5. HG: original soil, AF1: non–specifically bound As, AF2: specifically bound As, AF3: amorphous hydrous oxide bound As, AF4: crystalline hydrous oxide bound As, AF5: residual As. Figure 3. Transformation of As in the gastric and intestinal phases after addition of different dietary components before and after FeSO4 stabilization. Data are presented as the mean ± standard deviation (S.D.) of the three experimental groups. ANOVA analysis reveals the statistical differences between the stabilization treatments and dietary addition groups of different As fractions. Summary of statistical information including p values is given in Table S5. HG: original soil, AF1: non–specifically bound As, AF2: specifically bound As, AF3: amorphous hydrous oxide bound As, AF4: crystalline hydrous oxide bound As, AF5: residual As.

Figure 4. The correlation coefficients of different species of As (A) and Zn (B) with Fe fractions in soils. AsB: As bioaccessibility, AF1: non–specifically bound As, AF2: specifically bound As, AF3: amorphous hydrous oxide bound As, AF4: crystalline hydrous oxide bound As, AF5: residual As, ZnB: Zn bioaccessibility, ZF1: acid-exchangeable Zn, ZF2: reducible Zn, ZF3: oxidizable Zn, ZF4: residual Zn, FeB: Fe bioaccessibility, FF1: acid-exchangeable Fe, FF2: reducible Fe, FF3: oxidizable Fe, FF4: residual Fe.

Figure 4. The correlation coefficients of different species of As (A) and Zn (B) with Fe fractions in soils. AsB: As bioaccessibility, AF1: non–specifically bound As, AF2: specifically bound As, AF3: amorphous hydrous oxide bound As, AF4: crystalline hydrous oxide bound As, AF5: residual As, ZnB: Zn bioaccessibility, ZF1: acid-exchangeable Zn, ZF2: reducible Zn, ZF3: oxidizable Zn, ZF4: residual Zn, FeB: Fe bioaccessibility, FF1: acid-exchangeable Fe, FF2: reducible Fe, FF3: oxidizable Fe, FF4: residual Fe.

Figure 5. Transformation of Zn in the gastric and intestinal phases after addition of different dietary components before and after FeSO4 stabilization. Data are presented as the mean ± standard deviation (S.D.) of the three experimental groups. ANOVA analysis reveals the statistical differences between the stabilization treatments and dietary addition groups of different Zn fractions. Summary of statistical information including p values is given in Table S5. HG: original soil, ZF1: acid-exchangeable Zn, ZF2: reducible Zn, ZF3: oxidizable Zn, ZF4: residual Zn.

Figure 6. Hazard quotient (HQ) (A) and carcinogenic risk (CR) (B) of dietary components before and after FeSO4 stabilization. HG: risk assessment values based on the total concentration of soil heavy metals. HGB: risk assessment values based on the bioaccessibility of soil heavy metals.

Table 1. Physicochemical properties of the experimental soil.

Table 1. Physicochemical properties of the experimental soil.

Physicochemical PropertiesValue ± SDpH8.20 ± 0.01CEC (cmol∙kg−1)11.30 ± 0.2SOM (g∙kg−1)18.70 ± 0.6TP (%)0.16 ± 0.00TN (mg∙kg−1)108.00 ± 2.5TK (mg∙kg−1)1.14 ± 0.01Fe2O3 (%)30.84 ± 1.44Tas (mg∙kg−1)201.77 ± 2.56TZn (mg∙kg−1)1145.71 ± 13.42