Cadmium, copper and nickel distributions at four stations in the eastern central and south Atlantic

Abstract

Abstract Distributions of cadmium, copper and nickel at four stations in the eastern part of the Atlantic Ocean from 30 ° S to 34 ° N are described based on analytical results from three laboratories. The Cd and Ni profiles show nutrient-like distributions with concentrations in the deep waters increasing from north to south. Copper profiles all show gradual increases from surface to bottom with the highest concentrations occurring near bottom on the most northerly station. Variations in the deep-water Cd and Ni concentrations can be understood in terms of mixing of southern source waters with high concentrations with lower concentration northern source waters. The deep-water Cu distributions indicate a significant near-bottom source to the northern end of the section. Cadmium vs. phosphate relationships show features that result from both regeneration and mixing. Higher Cd:PO 4 ratios are seen in the southern source waters than in the northern waters, thus discounting the suggestion that the inflection in the global Cd:PO 4 relationship at PO 4 ≈ 1.3 μM originates in the southern ocean. Differential regeneration of Cd and PO 4 is seen through the equatorial oxygen minimum.