Trace metals in humic acids from recent Skagerrak sediments

Humic acids isolated from a sediment core from the eastern Skagerrak have been characterized by elementary analysis and IR analysis. Heavy metal concentrations in these isolates show a general trend to decrease with depth. IR-spectroscopic analysis indicates that functional groups of humic acids from deeper sediment layers differ from those of the uppermost samples. Higher contents of Ti and Cr and to a lesser extent of Zn, Cu, Mn, and V in the uppermost layer reflect an increase in supply of these elements in the youngest depositional history. While bulk sediments did not show significant enrichment humic acids are enriched in heavy metals.