Microbial effects on nickel and cadmium sorption and transport in volcanic tuff
- New Mexico Environment Dept., Santa Fe, NM (United States)
- New Mexico Inst. of Mining and Technology, Socoroo, NM (United States)
We performed sorption and transport experiments to determine how vadose-zone microbes affect sorption of Ni{sup 2+} and Cd{sup 2+} on crushed volcanic tuff and transport of Ni{sup 2+} in the same medium. Sorption of Ni{sup 2+} and Cd{sup 2+} to the tuff was less in samples inoculated with microbes than in sterile samples. Since Ni{sup 2+} sorption was the same both in the presence and absence of microbes when a buffer was used, microbes appear to decrease sorption by decreasing solution pH. Samples with Bacillus megaterium decreased Ni{sup 2+} sorption the most of the 14 subsurface microbial strains tested. Nickel isotherms were linear up to initial concentrations of 10 mg L{sup -1} with an average distribution coefficient (k{sub d}) of 7.4 L kg{sup -1} for samples with freeze-dried B. megaterium and 50 L kg{sup -1} for sterile samples containing 1 g L{sup -1} NaN{sub 3}. Sterile samples without NaN{sub 3} had a higher k{sub d} (185-265 L kg{sup -1}). We therefore predicted that the retardation of Ni{sup 2+} in inoculated columns would be law than in sterile columns. A transport experiment with both inoculated (inoculum consisted of freeze-dried B. megaterium) and sterile (solutions contained NaN{sub 3}) columns indicated that retardation (R) of Ni{sup 2+} was less for columns with microbes (R = 205) than for sterile columns (R = 307), but retardation was higher than predicted by batch sorption experiments in both groups of columns. Dispersion was lower in inoculated columns, possibly due to microbial clogging of secondary pores. The results indicate that microbes can increase the mobility of cationic metals in subsurface environments. 25 refs., 7 figs., 5 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 263105
- Report Number(s):
- CONF-9101175-; ISSN 0047-2425; TRN: 96:002035-0012
- Journal Information:
- Journal of Environmental Quality, Vol. 23, Issue 4; Conference: National symposium on naturally occurring radionuclides in agricultural products, Orlando, FL (United States), 24-25 Jan 1991; Other Information: PBD: Jul-Aug 1994
- Country of Publication:
- United States
- Language:
- English
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