Speciation of dissolved metals associated with organic matter in coastal seawaters

By combined use of chloroform extraction and Amberlite XAD-2 resin chromatography, metal-organic compounds dissolved in coastal seawaters of Harima Sound, the Seto Inland Sea, were separated into three groups: hydrophobic, hydrophilic neutral and basic, and hydrophilic acidic. The hydrophobic metal-organic compounds, which are associated with organic matter with molecular weight less than 300, accounted for only a small fraction of the metal-organic compounds; 6 % for Cu and an insignificant fraction for Fe, Mn and Zn. The hydrophilic metal-organic compounds with molecular weights between 100 and 1,500 were major components of the metal-organic compounds. The metals associated with the organic matter on average accounted for 12 % of the Fe, 11 % of the Mn, 7 % of the Zn and 23 % of the Cu of the reactive dissolved metals.