Research Feature: Dorthe Wildenschild Plans for a Sabbatical in Denmark and Australia

Posted: June 5, 2009

Dorthe
Dorthe Wildenschild is an associate professor of environmental engineering.

This next year, Dorthe Wildenschild's subsurface research will take her around the world to Denmark and Australia. The newly tenured faculty member in environmental engineering is an expert in the micro-scale processes that control how water and pollution move through soil and aquifers. During her sabbatical, Dorthe will work on projects related to colloidal transport, biofilms and the geologic sequestration of carbon dioxide – read on for Dorthe's definitions of these terms and to learn more about her research plans. Part of Dorthe's position has been funded by the Subsurface Biosphere Initiative.

What is your sabbatical schedule?

Starting in August, I am going to spend six months in Denmark and four months in Australia.  Denmark is my native country but it has been seven years since I lived there. 

What will be the focus of your research in Denmark and how does it relate to your current research?

Most of my previous research has focused on how two fluids – air and water, or water and an oily substance called NAPL’s move through the pore space between grains of sediment – this is called multi-phase flow and transport in porous media.  Subsurface scientists are interested in these processes because they influence how water, pollution, oil and gas, and microbes move through the subsurface. 

In Denmark, my research will focus on colloid transport. Colloids are tiny particles – between 10 nanometers to 10 micrometers in size that are suspended in a fluid. Often colloids are organic particles that contaminants can attach to – once the contaminants are bound to the colloid they spread in different ways than they would if they moved just by dissolution. Colloidal transport can increase the rate that substances such as contaminants or microbes spread through the subsurface.

Who will you collaborate with in Denmark?

I am going to work with Dr. Lis Wollesen de Jonge at the Research Centre Foulum University of Aarhus in Denmark.  She is an internationally recognized expert on colloid transport in natural systems. A lot of the work that Lis has done relates to how colloids enhance the movement of pesticides and fertilizers in the environment. She has also studied how colloids affect the movement of manure borne pathogens.

Dr. Wollesen de Jonge is an experimentalist and she focuses on column-scale and field scale projects. My own expertise is in working at smaller scales – with micro-scale experiments and advanced imaging techniques that let us create highly magnified images of fluids as they move past individual soil or sediment grains. Lis and I have submitted some proposals where we will combine our expertise – we’re going to try to see colloids in small scale images and combine that imaging with field and bench scale projects. One of the proposals we have submitted is to the U.S. Department of Energy – they are interested in this mechanism because they’ve seen colloidal enhanced transport of radionucl ides at the Hanford Site, for example.

After six months, you will move half-way around the world to Australia, what projects will you work on there?

I will work on a couple different projects.  I just recently received an exploratory research grant from DOE’s Environmental Remediation Sciences Program (ERSP) to image biofilms in porous media and I will be collaborating with a microbial ecologist named Dr. Iain Young at the University of New England in Armidale, New South Wales. Biofilms are growths of cells that form a structure. They form in all sorts of settings, from soil to your teeth. I am working on generating x-ray tomography images of biofilms so that the information about the biofilm architecture can be used in computer models built to predict biofilm function in porous media (soil or sand). Tomographic imaging is the technique used in medical x-ray CAT or CT scans. One of the first steps has been trying to demonstrate that what we see in the images is actually a biofilm. In this image, the background material is a glass bead pack, and the biofilm is the gooey substance protruding from the individual glass beads. To be able to see biofilms with x-rays, which is a fairly watery substance, we attach silver particles to the biofilm as shown on the right in the figure.

Biofilm image.
This is an X-ray tomographic image of biofilm grown in a glass bead pack. This image shows biofilm (the pink gooey substance) with silver particles (the bright white) attached to the outer surface. It was imaged with light microscopy. 

I will also spend some time collaborating with colleagues at Australia National University in Canberra and CSIRO Petroleum in Melbourne.  I will be working on geologic carbon sequestration – a proposed mechanism for combating global warming.  The process removes carbon dioxide from the atmosphere by capturing it at concentrated emission sources such as coal–fired power plants, and injecting it into the subsurface where it is either trapped or precipitated.  Australia is at the forefront of this type of research and operates one of the world’s largest research and geosequestration demonstration projects. My research will focus on a sequestration mechanism called capillary trapping. The goal with this mechanism is to trap carbon dioxide within little capillaries within aquifers so that it can dissolve into groundwater over time, and thereby prevented from escaping back to the atmosphere. People have been talking about the wonderful potential of this storage mechanism but there have been very few experiments done to verify that it will work.

Will some of your graduate students be involved in your research overseas?

Yes, one of my students, Danielle Jansik, received a Fulbright to spend a year in Denmark with the same research group. She will be part of program called “Soil It Is” at the University of Aarhus and Aalborg University.  It is a large graduate program with many international collaborators. Dannie will be the first in a series of graduate student exchanges – in coming years exchange PhD students from Denmark will come to work with our group here at OSU and study imaging technology.  It’s an exciting opportunity!

Another one of my current students, Ryan Armstrong, is working on microbially enhanced oil recovery.  He is going to spend some time at Australia National University while I am there. ANU has very good imaging equipment and also strong research ties to the oil industry – both of these strengths will provide great opportunities for Ryan.

What are you most excited about for your sabbatical?

I’m looking forward to having the time to think about science and research in a focused way. I think it’s going to be great! And it will give me a chance to learn some new things. All three projects – colloids, biofilms, and carbon sequestration are new research areas for me and I’m looking forward to having the time to dig into the nitty gritty.