Al and pH anomalies in the Manus Basin reappraised: comments on the paper by T. Gamo et al., “Hydrothermal plumes in the eastern Manus Basin, Bismarck Sea: CH4, Mn, Al and pH anomalies”

Water column pH and Al anomalies observed in the Manus Basin by Gamo et al. (Deep-Sea Sea Research I, 40, 1993, 2335–2349) ∼ 200m above their suspected source led them to suggest a high temperature (200–300°C), low pH hydrothermal fluid. However, the pH anomalies were more likely to have been caused by CO2H2S-rich fluids. In addition, solubility constraints suggest that the source of the observed Al anomalies at this site is not high temperature (200–300°C), low pH hydrothermal fluids. Instead, the data seem to suggest the issuance of fluids by some non-steady state volcanic/hydrothermal process.