R. Lee Penn
University of Minnesota, MN·Chemistry
Soils and sediments hold huge amounts of carbon, much of it in organic matter that clings to tiny iron oxide minerals. These iron oxide–organic matter pairings, called Fe-OM, help control how carbon and nutrients cycle around the globe.
- Fields
Chemistry
Earth & Environmental Science
Plant Science & Agriculture
- Topics
soil carbon
soil organic matter
iron oxide minerals
- Grants
- 1 known grant, through Aug 2028
What they work on
- Measure how organic matter is distributed and sorted between solid, liquid and interface phases as iron oxide minerals transform, a change sped up by dissolved Fe(II), the reduced form of iron, using synthesized iron minerals.
- Identify which model exudate compounds and whole root exudate molecules break apart iron oxide–organic matter assemblages (Fe-OM), releasing dissolved organic matter and Fe(II), and determine how they do it.
- Test whether exudate molecules that act both as reductants (electron donors) and chelates (metal binders) are especially effective at disrupting Fe-OM, and whether some Fe-OM materials resist transformation.
- Characterize how chemical gradients redistribute organic matter after adding Fe(II), model exudates or whole root exudate, using flow-through reactors that mimic field conditions.
- Develop an open-source machine learning model that predicts how organic molecules react with soil minerals, trained on data linking molecular structure to solid, liquid and interface distribution.
More about the research
The minerals often shield organic matter from breaking down, but plant roots release a mix of molecules, called root exudates, that may break these pairings apart. Understanding when Fe-OM holds together and when it falls apart could improve predictions of how much carbon soils store or release.
Why it matters
Knowing which plant-derived molecules release carbon held by soil iron minerals, and which minerals resist this, could help design strategies that increase soil carbon storage and support sustainable land use. The planned open-source machine learning model may also help predict the fate of other chemicals in soil, including pollutants, which is useful to environmental scientists and land managers.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Steven Hall
University of Wisconsin-Madison, WI·Earth & Environmental Science
Test whether variation in soil organic matter properties and cycling across U.S. ecosystems can be explained by three fundamental axes running from fast to slow biogeochemical rates, using samples and data from NEON sites.
Leanne Powers
SUNY College of Environmental Science and Forestry, NY·Chemistry
Measure apparent quantum yields, meaning how efficiently absorbed sunlight produces reactive species, for triplet DOM, singlet oxygen, superoxide, hydrogen peroxide and hydroxyl radical from field DOM and model compounds such as lignin, tannins and flavonoids.
Brandy Toner
University of Minnesota, MN·Earth & Environmental Science
Determine how dissolved organic carbon and iron-binding organic ligands control the 'colloidal shunt', in which tiny suspended iron particles clump with organic carbon and sink, using experiments across seasons and locations.
The school
University of Minnesota: 88 labs on PI Pages, $1.4B a year on research, 722 research doctorates a year.
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