Fig. 4.

Chromatogram showing P speciation of two samples of the Coonterunah carbonate (ALS-A and ALS-B) and of a hydrothermal control sample (ALS-C). P³⁺ is phosphite. No P species appeared within the 18.2 MΩ deionized water blank, and only phosphate (P⁵⁺) appeared in extracts of the other rocks listed in Table 1. These peaks correspond to concentration ratios (P³⁺/P total) of 40% (ALS-A) and 67% (ALS-B). Slight shifts in peak locations are attributable to peak wander as experiments run and are constrained by comparison with standards every five samples.