Distribution of chromium contamination and microbial activity in soil aggregates

Tetsu K. Tokunaga, Jiamin Wan, Terry C. Hazen, Egbert Schwartz, Mary K. Firestone, Stephen R. Sutton, Matthew Newville, Keith R. Olson, Antonio Lanzirotti, William Rao

Research output: Contribution to journalArticle

42 Citations (Scopus)

Abstract

Biogeochemical transformations of redox-sensitive chemicals in soils can be strongly transport-controlled and localized. This was tested through experiments on chromium diffusion and reduction in soil aggregates that were exposed to chromate solutions. Reduction of soluble Cr(VI) to insoluble Cr(III) occurred only within the surface layer of aggregates with higher available organic carbon and higher microbial respiration. Sharply terminated Cr diffusion fronts develop when the reduction rate increases rapidly with depth. The final state of such aggregates consists of a Cr-contaminated exterior, and an uncontaminated core, each having different microbial community compositions and activity. Microbial activity was significantly higher in the more reducing soils, while total microbial biomass was similar in all of the soils. The small fraction of Cr(VI) remaining unreduced resides along external surfaces of aggregates, leaving it potentially available to future transport down the soil profile. Using the Thiele modulus, Cr(VI) reduction in soil aggregates is shown to be diffusion rate- and reaction rate-limited in anaerobic and aerobic aggregates, respectively. Thus, spatially resolved chemical and microbiological measurements are necessary within anaerobic soil aggregates to characterize and predict the fate of Cr contamination. Typical methods of soil sampling and analyses that average over redox gradients within aggregates can erase important biogeochemical spatial relations necessary for understanding these environments.

Original languageEnglish (US)
Pages (from-to)541-549
Number of pages9
JournalJournal of Environmental Quality
Volume32
Issue number2
StatePublished - Mar 2003
Externally publishedYes

Fingerprint

soil aggregate
Chromium
microbial activity
chromium
Contamination
Soils
soil
chromate
reaction rate
community composition
soil profile
microbial community
surface layer
Chromates
respiration
organic carbon
contamination
distribution
Organic carbon
Reaction rates

ASJC Scopus subject areas

  • Environmental Science(all)
  • Environmental Chemistry

Cite this

Tokunaga, T. K., Wan, J., Hazen, T. C., Schwartz, E., Firestone, M. K., Sutton, S. R., ... Rao, W. (2003). Distribution of chromium contamination and microbial activity in soil aggregates. Journal of Environmental Quality, 32(2), 541-549.

Distribution of chromium contamination and microbial activity in soil aggregates. / Tokunaga, Tetsu K.; Wan, Jiamin; Hazen, Terry C.; Schwartz, Egbert; Firestone, Mary K.; Sutton, Stephen R.; Newville, Matthew; Olson, Keith R.; Lanzirotti, Antonio; Rao, William.

In: Journal of Environmental Quality, Vol. 32, No. 2, 03.2003, p. 541-549.

Research output: Contribution to journalArticle

Tokunaga, TK, Wan, J, Hazen, TC, Schwartz, E, Firestone, MK, Sutton, SR, Newville, M, Olson, KR, Lanzirotti, A & Rao, W 2003, 'Distribution of chromium contamination and microbial activity in soil aggregates', Journal of Environmental Quality, vol. 32, no. 2, pp. 541-549.
Tokunaga TK, Wan J, Hazen TC, Schwartz E, Firestone MK, Sutton SR et al. Distribution of chromium contamination and microbial activity in soil aggregates. Journal of Environmental Quality. 2003 Mar;32(2):541-549.
Tokunaga, Tetsu K. ; Wan, Jiamin ; Hazen, Terry C. ; Schwartz, Egbert ; Firestone, Mary K. ; Sutton, Stephen R. ; Newville, Matthew ; Olson, Keith R. ; Lanzirotti, Antonio ; Rao, William. / Distribution of chromium contamination and microbial activity in soil aggregates. In: Journal of Environmental Quality. 2003 ; Vol. 32, No. 2. pp. 541-549.
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