Magnus Skold

Solubility enhancement of seven metal contaminants using carboxymethyl-β-cyclodextrin (CMCD)

Carboxymethyl-beta-cyclodextrin (CMCD) has been suggested as a complexing agent for remediation of sites co-contaminated with metals and organic pollutants. As part of an attempt to construct a geochemical complexation model for metal-CMCD interactions, conditional formation constants for the complexes between CMCD and 7 metal ions (Ba, Ca, Cd, Ni, Pb, Sr, and Zn) are estimated from experimental data. Stable metal concentrations were reached after approximately 1 day and estimated logarithmic conditional formation constants range from -3.2 to -5.1 with confidence intervals within +/-0.08 log units. Experiments performed at 10 degrees C and 25 degrees C show that temperature affects the solubility of the metal salts but the strength of CMCD-metal complexes are not affected by this temperature variation. The conditional stability constants and complexation model presented in this work can be used to screen CMCD as a potential remediation agent for clean-up of contaminated soil and groundwater.

Magnetic Susceptibility Measurements as a Proxy for Bioremediation at Hydrocarbon Contaminated Sites

Magnetic susceptibility (MS) of sediments affected by hydrocarbon contaminated groundwater was studied at two sites. the sites used in the study are Bermidji MN, and Carson City, MI. Two cores were retrieved from Bemidji site; one from the contaminated area and the other from the background area. Three cores were collected from the Carson site; two within the contaminated area and one from the background area. All the cores that we collected extended from the unsaturated zone into the saturated zone. for the Bemidji site, there is a 0.9m hydrocarbon smear zone due to groundwater level fluctuations. for the Carson site, hydrocarbon smear zone is approximately 1-2 m. MS and Grain size data were collected from the cores from both sites. Our results show that MS increased towards the top of the GWT within the contaminated area of both sites. in contrast, the MS does not show any changes around the GWT within the clean cores of both sites. We postulate that this increase in MS is due to iron reducing microbes creating magnetite as a byproduct of hydrocarbon breakdown. Based on these results we conclude that the MS measurements can be used as a tool to investigate microbial activity within hydrocarbon contaminated zones.