Stability of Ferrihydrite–Humic Acid Coprecipitates under Iron-Reducing Conditions
Journal Article
·
· Environmental Science and Technology
- Univ. of Wisconsin, Madison, WI (United States); University of Wisconsin-Madison Department of Geoscience
- Univ. of Wisconsin, Madison, WI (United States)
- Univ. of Nevada, Reno, NV (United States)
Recent studies have suggested the potential for release of iron (hydr)oxide-bound organic carbon (OC) during dissimilatory iron oxide reduction (DIR). However, the stability of iron (hydr)oxide-bound OC in the presence of a natural microbial consortium capable of driving both OC metabolism and DIR has not been resolved. Pure ferrihydrite (Fhy) and Fhy-humic acid coprecipitates (Fhy-HA) were inoculated with a small quantity of freshwater sediment and incubated under anoxic conditions in the presence and absence of H2 or glucose as electron donors for DIR. H2 promoted DIR led to release of ca. 1 mM dissolved organic carbon (DOC). However, comparable amounts of DOC were released from both pure Fhy and Fhy-HA, similar to DOC levels in mineral-free, inoculum-only controls. These results suggest that the observed DOC release during H2-promoted DIR originated from OC contained in the inoculum as opposed to the much larger pool (ca. 38 mM) of OC in the Fhy-HA. Thus, DIR preferentially released sorbed OC with low aromaticity (inoculum OC) versus highly aromatic OC (HA) coprecipitated with iron oxide. Furthermore, our findings provide new insight into the extent and mechanisms by which DIR is likely to influence aqueous/solid-phase OC partitioning in anoxic soils and sediments.
- Research Organization:
- University of Nevada, Reno; University of Wisconsin-Madison
- Sponsoring Organization:
- USDOE Office of Science (SC), Biological and Environmental Research (BER)
- Grant/Contract Number:
- SC0014275; SC0016217
- OSTI ID:
- 1812867
- Alternate ID(s):
- OSTI ID: 1612130
- Journal Information:
- Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 22 Vol. 52; ISSN 0013-936X
- Publisher:
- American Chemical Society (ACS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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