ABSTRACT
In geothermal springs like Wai-O-Tapu with acidic to neutral and reduced conditions, the Eh-pH diagram in Figure 2 shows that all sites are situated in the arsenite (H3AsO3) stability field.
The HPLC-ICPMS analysis of water samples indicated arsenite (As[III]) as the predominant arsenic species, but in several pools arsenate (As[V]), methylated arsenic species as well as an unknown arsenic species could also be detected. A discrepancy can be seen between the arsenic speciation data and the total arsenic concentration in some pools (Figs. 3 and 4).
