Simultaneous dissolution of organic acids in sequential leaching of sediment bound trace metals

Abstract

Abstract Inorganic metal‐solid assocations can somewhat arbitrarily be characterized in various extraction procedures. The simultaneous extraction of organics (humic and fulvic acids, HFA, characterized by their UV absorbance) has been studied in the sequential leaching of sediment bound trace metals (Cd, Cu, Fe, Mn and Zn). Typically 2–5% of the total HFA would follow the ion exchangeable fraction, 4–10% the carbonate/hydroxide fraction and 7–13% the hydrous oxide fration. Essentially no HFA remains after wet oxidation with H2O2/HNO3. From the distribution of the metals and the HFA between the various leaching steps it appears that organics can constitute a significant structural component of the amorphous hydrous oxide phase (iron and manganese) which partly prevent the distribution of this fraction in reducing acidic media (NH2OH‐HC1). Key words: Sequential LeachingOrganic AcidsHumic and Fulvic AcidCadmiumCopperIronManganeseZinc