Education:
B.S. Chemistry Lake Superior State University
M.S. & Ph.D. Geochemistry Colorado School of Mines
Post-doctoral study at Water Studies Centre, Monash University, Melbourne, Australia

Research Interests:
Geochemical influences on metal transport and bioavailability, Environmental colloids and suspended particles; Natural organic matter; Field-flow fractionation methods; ICP-AES/MS methods; Chemistry of acid-mine drainage

Link to Geochemistry Program at CSM


Metals such as Cu, Zn, Ni, Cd, Pb enter aquatic and soil systems from numerous sources. The degree to which these metals are bioavailable depends in large part on their speciation, which is controled by water chemistry. The biotic ligand model (BLM) is one approach to relating water chemistry to the toxic effects of metals on aquatic and soil organisms. We are examining the application of the BLM systems that have been contaminated by past mining activities. As part of this research we are comparing the results of BLM modeling, conventional aquatic organism toxicity tests, and enzyme bioassays.

More info on metal bioavailability:

The Biotic Ligand Model: Technical Support Document for Its Application to the Evaluation of Water Quality Criteria for Copper

BIOAVAILABILITY OF METALS (pdf)


Environmental colloids can be described as particles smaller than one micrometer. They can make up a significant proportion of suspended sediments and are important in that they: effectively bind pollutants; do not readily settle out of surface waters; and are mobile in groundwaters. Consequently they can facilitate the transport of pollutants. Currently not much is known about the abundance and properties of environmental colloids. Much of my work has been involved in the development of methods to collect and analyze colloids from rivers, reservoirs, mountain streams, soil solutions, and groundwaters. One specific aspect of my research is how colloids effect the toxicity of metals. I have found tangential-flow filtration and ICP-AES to be an effective means of examining this.

More info on environmental colloids and suspended particles


Field-flow fractionation (FFF) is a family of related methods which provide a high-resolution, size separation of macromolecules, colloids and particles over an ultimate range of a few thousand daltons to 50 micrometers. One significant advantage of FFF over other size analysis methods is that it provides a separation which allows further analysis of colloids as a function of size. I have directly coupled FFF to; ICP-MS to obtain elemental composition of soil and aquatic colloids over a size range of 0.1-1.0 micrometers; and to ICP-AES to examine copper binding to humic substances over a molecular weight range of about 1,000 to 10,000 daltons. Currently I am using FFF to examine soil particle composition over a size range of 1-25 micrometers. Other methods we have used in conjunction with FFF are electron microscopy and X-ray diffraction.

More Info on Field-Flow Fractionation


Another area of research interest is in the chemistry of acid-mine drainage (AMD) generation. Colorado, and other western states, has a rich history of mining, which unfortunately has also left us with the environmental consequences of sulfide weathering. The sulfide minerals present in the ores and surrounding rock oxidize to form sulfuric acid. Release of metals from the sulfide mineral oxidation, and from further acid attack on the rock, create water quality problems in surface and ground waters which receive acid mine drainage. At the heart of the formation of AMD, and the remediation of AMD, lie complex geochemical reactions. These reactions can include: mineral dissolution/precipitation; adsorption/desorption; and microbiological reactions. I am currently examining the mechanisms and rates of weathering of mine-tailings deposits that occur along the Upper Arkansas River.

More Info on Acid Mine Drainage


Selected Publications and Published Abstracts: