Complexing capacity of heavy metals with humic substances in sediments from the Taiwan Erhjin Chi coastal area

Heavy metals in humic substances, mainly humic and fulvic acids isolated from the Taiwan Erhjin coastal sediments, were determined by atomic absorption spectrophotometry. Results show that higher concentrations of lead (range from 12.0 ug/g to 49.5 ug/g), iron (15.2 to 114 ug/g) and manganese (119 to 454 ug/g) were found in the fraction of humic acid compared with those in fulvic acid. The contents of lead, iron and manganese in fulvic acid were below the detection limits. However, the copper contents (from 165 to 1750 ug/g) in fulvic acid were much higher than in humic acid (282 to 821 ug/g).

For the copper species, such as: exchangeable, skeletal, easily reducible, organic combined with humic substances, moderately reducible, organic residues with sulfide, and detritus with mineral, in the Taiwan Erhjin chi sediments have been analyzed by sequential leaching methods. In general, higher percentages of copper in organic residues with sulfide were found in association with the higher concentrations of sulfide in the anoxic sediments. Finally, the competition of organic copper between humic substances and organic residues with sulfides were discussed and evaluated.

Keywords:

• Copper species
• humic substances
• pyrite and acid volatile sulfides
• Taiwan Erhjin Chi riverine and coastal sediments

Notes

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