Molecular weight and trace metal distributions in fulvic and humic acid fractions of coastal marine sediments

Abstract

Molecular weight and trace metal distributions of fulvic and humic acid fractions of marine sediments from the Seto Inland Sea were investigated by using a gel filtration technique in combination with atomic absorption and emission spectrometries. A binary molecular weight distribution was found both in the fulvic acid fraction and in the humic acid fraction. The fulvic acid fractions with molecular weights of less than 1.5×103 and of 5×103−104 accounted for 38–57 % and 25–41 % of the total fulvic acids, respectively, and the humic acid fractions with molecular weights of 102−104 and of over 2×105 accounted for 58–73 % and 16–27 % of the total humic acids, respectively. The components with molecular weights of over 1.5×103 contained 54 %, on average, of the Fe, Zn and Cu in the fulvic acid fraction, and the components with molecular weights of over 104 contained 58 %, on average, of these metals in the humic acid fraction.