BER launches Environmental System Science Program. Visit our new website under construction!

U.S. Department of Energy Office of Biological and Environmental Research

BER Research Highlights

Synthetic Iron (Hydr)oxide-Glucose Associations in Subsurface Soil: Effects on Decomposability of Mineral-Associated Carbon
Published: September 14, 2017
Posted: November 21, 2017

Soil minerals stabilize highly decomposable compounds like glucose.

The Science 
Recent field studies suggest that interactions with soil mineral phases can stabilize otherwise biodegradable organic matter (OM) in soils against microbial decomposition. To directly assess the effect of organo-mineral associations on an easily decomposable substrate (glucose), the research team conducted a series of laboratory incubations with well-characterized minerals (goethite and ferrihydrite) and native soils from three soil depths. Indeed, while free glucose added to soil was completely respired by microbes within 80 days, almost no glucose that had been sorbed to minerals before incorporation into soil was respired (~100% versus 0.4%, respectively).

The Impact
(1) This study provides direct evidence that even the most chemically labile organic substrates can be protected from microbial decomposition via association with mineral phases [in this case iron (hydro)oxide]. (2) These results support the emerging view that molecular structure is not the sole determinant of soil organic carbon (SOC) stability. (3) The efficacy of the laboratory approach demonstrates that microbial respired CO2 can be used as a tracer for OM desorption in soil, creating additional research opportunities.

Empirical field-based studies have provided indirect evidence of the capacity of soil minerals to stabilize organic carbon in soil. However, uncertainties remain as to the effect of mineral association on the bioavailability of organic compounds. To assess the impact of mineral association on the decomposition of glucose, an easily respirable organic substrate, a series of laboratory incubations was conducted with soils from 15, 50, and 85 cm. 13C-labeled glucose was added either directly to native soil or sorbed to one of two synthetic iron (Fe) (hydr)oxides (goethite and ferrihydrite) that differ in crystallinity and affinity for glucose. This study demonstrates that association with Fe (hydr)oxide minerals effectively reduced decomposition of glucose by ~99.5% relative to the rate of decomposition for free glucose in soil. These results emphasize the key role of mineral-organic associations in regulating the fluxes of carbon from soils to the atmosphere by enhancing the persistence of SOC stocks.

BER Program Manager
Daniel B. Stover
Office of Biological and Environmental Research Climate and Environmental Sciences Division (301-903-0289)

Principal Investigator
Margaret S. Torn
Lawrence Berkeley National Laboratory EESA/CESD (510-495-2223)

This work was supported as part of the Terrestrial Ecosystem Science program of the Office of Biological and Environmental Research, within the U.S. Department of Energy Office of Science, under Contract No. DE-AC02-05CH11231.

Porras, R.C., C.E. Hicks Pries, M.S. Torn, and P.S. Nico. “Synthetic iron (hydr)oxide-glucose associations in subsurface soil: Effects on decomposability of mineral associated carbon.” Science of The Total Environment 61314, 342–351 (2017). [DOI:10.1016/j.scitotenv.2017.08.290]

Topic Areas:

  • Research Area: Terrestrial Ecosystem Science
  • Research Area: Carbon Cycle, Nutrient Cycling

Division: SC-33.1 Earth and Environmental Sciences Division, BER


BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER

Recent Highlights

Jan 11, 2022
No Honor Among Copper Thieves
Findings provide a novel means to manipulate methanotrophs for a variety of environmental and in [more...]

Dec 06, 2021
New Genome Editing Tools Can Edit Within Microbial Communities
Two new technologies allow scientists to edit specific species and genes within complex laborato [more...]

Oct 27, 2021
Fungal Recyclers: Fungi Reuse Fire-Altered Organic Matter
Degrading pyrogenic (fire-affected) organic matter is an important ecosystem function of fungi i [more...]

Oct 19, 2021
Microbes Offer a Glimpse into the Future of Climate Change
Scientists identify key features in microbes that predict how warming affects carbon dioxide emi [more...]

Aug 25, 2021
Assessing the Production Cost and Carbon Footprint of a Promising Aviation Biofuel
Biomass-derived DMCO has the potential to serve as a low-carbon, high-performance jet fuel blend [more...]

List all highlights (possible long download time)