Hydrothermal sediment plumes on mid-ocean ridges undergo a change from a hot, dense, buoyant, sulfide rich mixture near the vent opening to a cooler, more dilute, oxy-hydroxide rich mixture away from the source. This proposal will study the changes which occur as the fluids and solids in these mixtures simultaneously cool, undergo diagenesis, and react with dissolved ions in the surrounding waters. Two vents of varying chemistry will be samples with special equipment, designed to reduce the effects of contamination. In particular the solid phases will be analyzed to determine the effects of sulfide/oxy-hydroxide mineralogy on the adsorption/release of specific ions. In that the volumes of materials emitted from these vents are significant in terms of the geochemical budgets of many elements in the oceans, work of this type will be useful in helping us to further understand the details of the recycling of these elements.
