FY 1991

A comparison of the scavenging of phosphorus and arsenic from seawater by hydrothermal iron oxyhydroxides in the Atlantic and Pacific oceans

Feely, R.A., J.H. Trefry, G.J. Massoth, and S. Metz

Deep-Sea Res., 38(6), doi: 10.1016/0198-0149(91)90001-V, 617–623 (1991)

Studies of hydrothermal plumes on the Juan de Fuca Ridge and the Mid-Atlantic Ridge indicate that newly-formed Fe oxyhydroxides, formed as a consequence of hydrothermal venting, readily scavenge P and As from seawater in proportion to the dissolved concentrations of these elements. The Fe content of the suspended matter decreases from 40% near the vents to <5% in ambient seawater, with particulate P and As concentrations correlating well with Fe throughout this range. The P/Fe ratio in the oxyhydroxide phase is about 1.8 times higher in Juan de Fuca Ridge samples relative to samples from the Mid-Atlantic Ridge. In contrast, the As/Fe ratio in the oxyhydroxide phase is about the same for both regions. Calculated distribution coefficients for P and As in the Fe oxyhydroxide phase show remarkable agreement between the Atlantic and Pacific Oceans. Thus, inter-ocean variations in the element/Fe ratios are a function of dissolved concentrations of the chemical species.