Data for suspended particles from hydrothermal plumes on the Mid-Atlantic Ridge (MAR) support uptake of dissolved V and As during formation of Fe oxides and release of Cu and Cd during alteration of sulfides. To complement these field observations, we carried out laboratory time series experiments to determine the stability of V, As, Cu, and Cd in precipitates from hydrothermal plumes on the MAR and Juan de Fuca Ridge. For V and As, the metal/Fe ratio in plume particles remained uniform after sampling. In contrast to V and As, particulate Cu and Cd values decreased relative to Fe over time in laboratory studies using both plume particles and mound-derived sulfides. The combined field and laboratory results show that scavenging is an important removal mechanism for seawater V and As, whereas oxidative dissolution of hydrothermal precipitates in seawater adds Cu and Cd to the ocean. ¿ American Geophysical Union 1993