Palladium and nickel in north-east Pacific waters

Platinum group metals have not previously been analysed in seawater. However, they have unique chemical properties, such as their various oxidation states and their strong tendencies for complex formation¹, and have been used as a potential indicator of the presence of meteoritic material ^2-4. Moreover, they may have been dispersed about the environment from their use in catalytic converters for internal combustion engines, especially palladium⁵. Here I report the first palladium profiles in marine water and sediment columns. Palladium concentration in the water column of the north-east Pacific increases from 0.18 pmol kg^-1 at the surface to 0.66 pmol kg^-1 in deep waters. There is a strong co-variance between palladium and nickel, which implies similar biogeochemical pathways. Significant palladium enrichment in recent sediments from the Palace Moat, Tokyo, Japan, is observed and is perhaps a consequence of palladium usage in automobiles.