**Results of analysis of variance (ANOVA)**

A one-way analysis of variance (ANOVA) was performed on each of the three regions studied. For SSR, the ANOVA showed that that the mean As levels between sites were not significantly different (SSR: *P*=0.398), but were for ESR and WSR (*P*<0.0016, *P*<0.015, respectively).

#### **Multivariate analysis results**
