XAFS CHARACTERIZATION OF COPPER CONTAMINATION IN THE UNSATURATED AND SATURATED ZONES OF A SOIL-PROFILE

The fate of heavy-metal contaminants in the environment, and the desig n and success of remediation strategies at hazardous waste sites depen d on the chemical speciation of the contaminants. The objective of thi s study was to determine the molecular-scale chemical form (species) o f heavy metals in different zones of a contaminated soil having a shal low ground water table. Copper in the unsaturated surface horizon and the water-saturated and partially-saturated subsurface horizons of a d isturbed soil from the lower eastern coastal plain of North Carolina w as characterized using XAFS spectroscopy. Extended x-ray absorption fi ne structure (EXAFS) and x-ray absorption near edge structure (XANES) data showed that the dominant form of Cu(II) bonding ranged from Cu-S in the deeper soil zones to Cu-O in the shallowest zone. The results s uggest that the surface and subsurface horizons will respond different ly to remediation treatments.