Book Description

To provide information useful for determining the biogeochemical cycling of corrosion products in the benthic boundary layer of the deep ocean, neutron-activated stainless steel was exposed to seawater and to Northeast Pacific red clay under aerobic and non-oxygenated conditions. This report describes the trace metal geochemistry of the sediment and the chemical speciation of the corrosion products. The sediments generally consisted of reddish-brown clay at the surface grading to a dark-brown transition zone below which mottled olive-gray clay prevailed. Neutron-irradiated 347 stainless steel specimens were exposed to seawater and sediment slurry under aerobic and non-oxygenated conditions for 108 days. The presence of aerated sediment more than doubled the amount of corrosion products released compared to aerated seawater and non-oxygenated sediment treatments. The distribution of 6°Co released from the stainless steel exposed to aerated seawater show that almost 70% of 6°Co activity became associated with suspended particulate matter. No detectable 6°Co activity was present in the soluble, readily dissolved, or inorganic or weakly complexed fractions of aerated sediment which had been used to treat neutron-activated stainless steel. Almost 50% of the 6°Co activity was extracted in the combined soluble, easily dissolved, adsorbed, and organically complexed fractions from the non-oxygenated sediment treatment indicating that this much of the corrosion products may be initially released in ionic form.