Progress 10/01/00 to 09/30/06
Outputs
Phytoremediation can be a cost-effective and low-maintenance means of remediating crude oil-contaminated soil. The objective of the field study was to evaluate the effects of vegetation establishment and fertilizer additions on remediation of crude oil-contaminated soil. Four replications of the following treatments were used: non-fertilized vegetation-free control; fescue + fertilizer; or bermudagrass + fertilizer. Vegetation was successfully established at the site and samples were collected annually for 5 yr. Soil chemical and biological properties were analyzed and the initial GC/FID total petroleum hydrocarbon (TPH) concentration of 18,600 mg/kg was reduced to 7,800 and 5,200 mg/kg for the control and vegetated + fertilized treatments, respectively, after 57 mo. Results indicated bacteria levels were greater in the vegetated + fertilized plots than in the control. Mean shoot biomass yields at 45 mo were 355 and 235 g/m2 for the bermudagrass + fertilizer and fescue
+ fertilizer, respectively. Mean root length at 45 mo were 159 and 95 km/m3 for the bermudagrass + fertilizer and fescue + fertilizer, respectively. Bacterial and TPH degrader numbers increased in response to vegetation establishment and fertilizer addition during the study. Phytoremediation of a crude oil-contaminated soil was demonstrated in the field study.
Impacts
A five-year field study showed that addition of fertilizer and establishment of vegetation increased remediation of a crude oil-contaminated soil.
Publications
- Thoma, G.J., T. Lam, P.-T. Hsu, K. Karim, and D. Wolf. 2006. In-situ measurement of rhizosphere degradation kinetics. In Annual Meeting Abstracts [CD-ROM]. ASA, CSSA, SSSA, Madison, WI.
- Thoma, G.J., T. Lam, P.-T. Hsu, K. Karim, D. Wolf, and S. Ziegler. 2006. In-situ measurement of rhizosphere degradation kinetics. In 2006 AIChE Annual Meeting. 12-17 November 2006. San Francisco, CA. American Institute of Chemical Engineers, New York.
- White, Jr., P.M., D.C. Wolf, G.J. Thoma, and C.M. Reynolds. 2006. Phytoremediation of alkylated polycyclic aromatic hydrocarbons in a crude oil-contaminated soil. Water Air Soil Pollut. 169:207-220.
- Duncan, K., S. AbuBakr, K.L. Sublette, E.M. Jennings, N. Alahari, G. Thoma, D. Wolf and J. Davis. 2006. Efficacy of various treatments of the restoration of nitrogen cycling in tallgrass prairie impacted by oil and brine spills. . p. 35. In 13th Ann. Int. Petroleum Environ. Conf. 17-20 October 2006. San Antonio, TX. Integrated Petroleum Environmental Consortium, Tulsa, OK
- Karim, K., G.J., Thoma, K.J. Davis, E.E. Gbur, and D.C. Wolf. 2006. Influence of sampling variability in assessing phytoremediation effectiveness of a crude oil-contaminated soil. p. 73. In 13th Ann. Int. Petroleum Environ. Conf. 17-20 October 2006. San Antonio, TX. Integrated Petroleum Environmental Consortium, Tulsa, OK.
- Karim, K., G.J., Thoma, P.-T. Hsu, T. Ho, and D.C. Wolf. 2006. Effect of nitrogen addition on rhizo-degradation rates of pyrene. p. 74. In 13th Ann. Int. Petroleum Environ. Conf. 17-20 October 2006. San Antonio, TX. Integrated Petroleum Environmental Consortium, Tulsa, OK.
- Karim, K., G.J., Thoma, P. White, K. Davis, and D. Wolf. 2006. A field study evaluating phytoremediation of a crude oil-contaminated soil. In Annual Meeting Abstracts [CD-ROM]. ASA, CSSA, SSSA, Madison, WI.
- Moscoso, O.A. 2006 Phytoremediation of pyrene-contaminated soil: Analysis of nitrogen addition and plant root parameters. M.S. Thesis. Univ. of Arkansas, Fayetteville.
- Thoma, G.J., K. Karim, D. Wolf, P. White, O. Alba, and K. Davis. 2006. A five-year field study to evaluate phytoremediation of a crude oil-contaminated soil. In 2006 AIChE Annual Meeting. 12-17 November 2006. San Francisco, CA. American Institute of Chemical Engineers, New York.
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Progress 01/01/05 to 12/31/05
Outputs
Phytoremediation is a method in which plants, microorganisms in the soil and in the rhizosphere, soil amendments, and the application of agronomic techniques interact to enhance contaminant degradation. We hypothesized that it was possible to improve remediation of pyrene-contaminated soil by adding an appropriate amount of N fertilizer and growing bermudagrass (Cynodon dactylon L). Captina silt loam (fine-silty, siliceous, active, mesic Typic Fragiudult) contaminated with 0 or 1000 mg pyrene/kg of soil was amended with urea at pyrene-carbon:urea-nitrogen (C:N) ratios of 4.5:1, 9:1, 18:1, or unamended (36:1). Zero, one, two, or three bermudagrass sprigs were planted per pot and -33 kPa moisture potential was maintained. Pyrene concentrations, polyaromatic hydrocarbon (PAH) and pyrene degrader microbial numbers, shoot and root parameters, ammonium-N, and nitrate-N levels were measured following the 100-d greenhouse study. After 100 days, at a C:N ratio of 4.5:1 the
presence of plants enhanced pyrene degradation. With no plants and C:N ratios of 4.5:1, 9:1, 18:1, and 36:1, the average pyrene remaining was 69, 48, 22, and 12%, respectively, indicating that an increase in N concentration in the soil had a negative effect on pyrene decomposition. Additionally, none of the one, two, or three plants at any of the C:N ratios were different with a mean value of 311 mg pyrene/kg soil, which would indicate that the presence of plants did not enhance pyrene degradation in the higher C:N treatments. Root surface area was not different for two or three plants, but both values were greater than the surface area of one plant. The PAH degrading microbial numbers were significantly higher in the pyrene-contaminated soil compared to the control with values of 7.69 and 2.74 log10 MPN/g, respectively. Pyrene reduced shoot and root biomass, root length, and root surface area, but increased root diameter. At a high N rate bermudagrass increased pyrene degradation,
but without plants pyrene decomposition was reduced.
Impacts
Phytoremediation can be an effective and cost efficient technology for cleaning up contaminated soils. Proper plant selection and soil fertility levels can increase contaminant degradation rates and quantities. The research demonstrated the importance of nitrogen fertilizer on plant growth and contaminant removal.
Publications
- Thoma, G., T.B. Lam, S. Ziegler, and D. Wolf. 2005. Novel approaches to measurement of rhizosphere effects in phytoremediation of oil contaminated soils. Third Int. Phytotechnologies Conf. 20-22 April 2005. Atlanta, GA. Available online at http://www.cluin.org/phytoconf/agenda.cfm.
- Krutz, L.J., C.A. Beyrouty, T.J. Gentry, D.C. Wolf, and C.M. Reynolds. 2005. Selective enrichment of a pyrene degrader population and enhanced pyrene degradation in bermudagrass rhizosphere. Biol. Fert. Soils. 41:359-364.
- Ziegler, S.E., P.M. White, D.C. Wolf, and G.J. Thoma. 2005. Tracking the fate and recycling of 13C-labeled glucose in soil. Soil Sci. 170:767-778.
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Progress 01/01/04 to 12/30/04
Outputs
Abiotic factors can influence the rate and efficiency of petroleum hydrocarbon degradation by microorganisms in crude oil-contaminated soil. The objective of this laboratory study was to determine the influence of temperature, moisture, and nitrogen (N) addition on hexadecane degradation in a Captina silt loam. In a first study, the soil was amended with 600 mg hexadecane/kg soil and incubated at 18 or 28oC, moisture potentials of -33 or -200 kPa, and an N addition rate of 50 mg/kg supplied as KNO3. In a second study, incubation temperatures of 18 or 28oC and N rates of 0 or 50 mg/kg were applied to soils amended with 600 mg hexadecane/kg soil. For both studies, destructive sampling occurred daily and samples were analyzed by gas chromatography with flame ionization detection. First order kinetics were used to evaluate the hexadecane degradation rate constants (k). Results indicated that temperature significantly affected the degradation rates which were greater at 28
than 18oC, with k values of 0.53 and 0.34/day, respectively, for the first study, and 0.59 and 0.37/day, respectively, for the second study. Under the conditions of this study, moisture and N addition levels did not significantly influence k values. Therefore, soil temperature can be an important consideration in determining biodegradation rates of crude oil components in soil.
Impacts
Contaminated soils can be effectively phytoremediated in situ, however, soil nutrients are often a limiting factor. Increasing nutrients available to plants could improve plant growth and enhance the remediation process.
Publications
- Greer, K.M., S.E. Ziegler, G.J. Thoma, K.J. Davis, and D.C. Wolf. 2004. Influence of abiotic factors on hexadecane biodegradation in a Captina silt loam. p. 85-86. In 11th Annual International Petroleum Environmental Conference. 12-15 October 2004. Albuquerque, NM. Integrated Petroleum Environmental Consortium, Tulsa, OK.
- Greer, K.M., S.E. Ziegler, G.J. Thoma, K.J. Davis, and D.C. Wolf. 2004. Microbial degradation of hexadecane in soil. In Annual Meetings Abstracts [CD-ROM]. ASA, CSSA, SSSA, Madison, WI.
- Lam, T., G.J. Thoma, D.C. Wolf, and S.E. Ziegler. 2004. Novel approaches to measurement of rhizosphere. p. 51. In 11th Annual International Petroleum Environmental Conference. 12-15 October 2004. Albuquerque, NM. Integrated Petroleum Environmental Consortium, Tulsa, OK.
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Progress 01/01/03 to 12/31/03
Outputs
Phytoremediation relies on plants to increase biological activity to enhance crude-oil biodegradation. A field study at a crude-oil contaminated site was conducted to: 1) determine the influence of plants on bacteria, fungi, and nematode numbers; and 2) assess plant growth. Four replications of the following treatments were used: non-vegetated non-fertilized control; fescue-ryegrass mixture + fertilizer; and bermudagrass-fescue mixture + fertilizer. The initial soil gravimetric total petroleum hydrocarbon concentration was 25,200 mg/kg. Vegetation was successfully established at the site and samples were collected at six times over a period of 4 y. Results indicated bacteria levels were greater in the vegetated + fertilized plots than in the control with values of 6.55, 6.56, and 5.66 log colony forming units/g dry soil in the fescue-ryegrass mixture + fertilizer, bermudagrass-fescue mixture + fertilizer, and the non-vegetated non-fertilized control, respectively. The
fungi and nematode numbers showed a similar pattern. Mean shoot biomass yields for the six sample times were 102 and 76 g/m2 for the bermudagrass-fescue mixture + fertilizer and fescue-ryegrass mixture + fertilizer, respectively. Bacteria, fungi, and nematode numbers increased in response to vegetation establishment and fertilizer addition during phytoremediation of the crude oil-contaminated site.
Impacts
Contaminated soils can be effectively phytoremediated in situ, however, soil nutrients are often a limiting factor. Increasing nutrients available to plants could improve plant growth and enhance the remediation process.
Publications
- Thoma, G. J., Lam, T. B., and Wolf, D. C. 2003a. Mathematical modeling of phytoremediation of oil-contaminated soil: Model development. Int. J. Phytorem. 5:41-55.
- Thoma, G. J., Lam, T. B., and Wolf, D. C. 2003b. Mathematical modeling of phytoremediation of oil-contaminated soil: Sensitivity analysis. Int. J. Phytorem. 5:125-136.
- Thoma, G., D. Wolf, and S. Ziegler. 2003. Mathematical modeling of phytoremediaiton of crude oil contaminated soils. p. 78. In 10th Annual International Petroleum Environmental Conference. 11-14 November 2003. Houston, TX. Integrated Petroleum Environmental Consortium, Tulsa, OK.
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Progress 01/01/02 to 12/31/02
Outputs
Phytoremediation uses plants and agronomic techniques to enhance biodegradation of hydrocarbons in contaminated soil. The objective of the field study was to evaluate fertilizer addition and vegetation establishment on remediation of crude oil-contaminated soil. Four replications of the following treatments were used: vegetation-free non-fertilized control; fescue (Festuca arundinacea Schreb.) - ryegrass (Lolium multiflorum L.) mixture + fertilizer; or bermudagrass (Cynodon dactylon (L.) Pers.) - fescue mixture + fertilizer. Soil chemical properties were analyzed at 0, 6, 17, and 21 mo and soil microbial levels at 6, 17, and 21 mo after initiation of the experiment. After 21 mo, total petroleum hydrocarbon (TPH) levels were 50% lower across all treatments. The vegetated fertilized plots had lower TPH/hopane levels than the control. The vegetated fertilized plots had lower levels of recalcitrant polycyclic aromatic hydrocarbons (PAH) than the control. Fertilizer
addition and vegetation establishment also increased total bacterial, fungal, and PAH degrader numbers. The data show that the phytoremediation treatments increased microbial populations and reduced contaminant levels.
Impacts
Contaminated soils can be effectively phytoremediated in situ, however, soil nutrients are often a limiting factor. Increasing nutrients available to plants could improve plant growth and enhance the remediation process.
Publications
- Kirkpatrick, W.D. 2002. Selecting plants and nitrogen rates to vegetate crude oil-contaminated soil. M.S. thesis. Univ. of Arkansas, Fayetteville.
- White, Jr., P.M. 2002. Phytoremediation of crude oil-contaminated soil. M.S. thesis. Univ. of Arkansas, Fayetteville.
- White, Jr., P.M., D.C. Wolf, G.J. Thoma, C.M. Reynolds, and E.E. Gbur. 2002. Effects of plants and fertilizer on the remediation of crude oil-contaminated soil. In Annual Meetings Abstracts [CD-ROM]. ASA, CSSA, SSSA, Madison, WI.
- White, Jr., P.M., W.D. Kirkpatrick, G.J. Thoma, and D.C. Wolf. 2002. Field evaluation of crude oil-contaminated soil phytoremediation. In Abstracts of technical papers, 2002 annu. meet., S. Branch, ASA, 29th, Orlando, FL. 3-5 Feb. 2002. ASA, Madison, WI.
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Progress 01/01/01 to 12/31/01
Outputs
Phytoremediation of crude oil-contaminated soil generally requires addition of N to increase plant growth. Our research objective was to determine the effects of N additions on growth of four warm-season plant species. Three grasses, pearlmillet, browntop millet, and sudangrass, and one legume, jointvetch, were grown in a soil contaminated with 3% by weight weathered crude oil. Ammonium chloride was added based on total petroleum hydrocarbon-C:total added N (TPH-C:TN) at ratios of 80:1, 60:1, 40:1, and 20:1. Plant biomass was determined and root length, surface area, and volume were analyzed. Total hydrocarbon, alkane, and polycyclic aromatic hydrocarbon (PAH) degrading microbial populations were enumerated from bulk and rhizosphere soil for sudangrass and jointvetch and bulk soil populations were enumerated in non-vegetated pots across all fertilizer treatments. Pearlmillet had significantly higher root length, surface area, and volume than other species when grown
at 40:1 and 20:1 TPH-C:TN. Total hydrocarbon, alkane, and PAH degrader levels in the rhizosphere were 6, 2, and 6 times larger, respectively, than numbers in bulk soil across all N rates. By determining the optimum N application rate for a crude oil-contaminated soil, increased plant production should occur that could enhance the potential for phytoremediation.
Impacts
Contaminated soils can be effectively phytoremediated in situ, however, soil nutrients are often a limiting factor. Increasing nutrients available to plants could improve plant growth and enhance the remediation process.
Publications
- Kirkpatrick, W.D., P.M. White, Jr., G.J. Thoma, E.E. Gbur, C.M. Reynolds, and D.C. Wolf. 2001. Plant response to nitrogen addition in a crude oil-contaminated soil. In Annual Meetings Abstracts [CD-ROM]. ASA, CSSA, SSSA, Madison, WI.
- White, Jr., P.M., W.D. Kirkpatrick, D.C. Wolf, G.J. Thoma, and R.M. Reynolds. 2001. Phytoremediation of crude oil-contaminated soil. p. 96. In Eighth Annu. Int. Petroleum Environmental Conf. Houston, TX. 6-9 Nov. 2001. Integrated Petroleum Environmental Consortium, Tulsa, OK.
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Progress 01/01/00 to 12/31/00
Outputs
Limited information is available on plant species that can germinate and survive in contaminated soil. Our research objective was to determine germination, seedling emergence, and survival of 23 cool- and warm-season grasses and legumes grown in soil having 5.3% Total Petroleum Hydrocarbon contamination from weathered crude oil. Germination and seedling emergence were monitored daily and survival was determined as the number of plants living 14 d after emergence of the first seedling. Of the plant species evaluated, the cool-season species had higher germination rates than warm-season species, while the majority of plants that germinated exhibited high survival rates. Based on the criteria that seedling emergence in contaminated soil must be >70% and survival must be >90%, the following plant species have potential for use in phytoremediation of the crude oil-contaminated soil studied: Warm-season grasses - sudangrass and browntop millet; Warm-season legumes -
American jointvetch, hairy vetch, Korean and striate lespedeza; Cool-season grasses - ryegrass, wheat, fescue, and oat; Cool-season legumes - crimson clover.
Impacts
Phytoremediation can be an effective method of remediating contaminated soils in situ. Enhanced phytoremediation could occur by combining cool- and warm-season species to increase the period of active plant growth.
Publications
- Kirkpatrick, W.D., P.M. White, Jr., D.C. Wolf, G.J. Thoma, and C.M. Reynolds. 2000. Germination and survival of plant species in a crude oil-contaminated soil. p. 256. In 2000 Agronomy abstracts. ASA, Madison, WI.
- Kirkpatrick, W.D., D.C. Wolf, and G.J. Thoma. 2000. Selection of plants for phytoremediation of a crude oil-contaminated soil. p. 9 In Volume 4 Abstracts Arkansas Crop Protection Assoc. 30 Nov. - 1 Dec. 2000. Fayetteville, AR.
- Thoma, G., D. Wolf, C. Beyrouty, and R. Reynolds. 2000. Using plants to remediate petroleum-contaminated soil. Bureau of Land Management Annual Conf. 24 July 2000. Albuquerque, NM.
- White, Jr., P.M., W.D. Kirkpatrick, D.C. Wolf, G.J. Thoma, and C.M. Reynolds. 2000. Survival and growth of five plant species in a petroleum-contaminated soil. p. 255. In 2000 Agronomy abstracts. ASA, Madison, WI.
- White, Jr., P.M., D.C. Wolf, and G.J. Thoma. 2000. Influence of soil amendments on plant growth in a petroleum-contaminated soil. p. 10. In Volume 4 Abstracts Arkansas Crop Protection Assoc. 30 Nov. - 1 Dec. 2000. Fayetteville, AR.
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Progress 01/01/99 to 12/31/99
Outputs
An active degrader population is necessary for bioremediation to occur. To enhance understanding of degraders in polycyclic aromatic hydrocarbon- contaminated soil, two growth chamber studies were conducted: (1) Captina silt loam (fine-silty, siliceous, mesic Typic Fragiudults) was contaminated with 0 or 2000 mg pyrene/kg and sampled after 61 wk, and (2) Captina silt loam was contaminated with 0 or 505 mg pyrene + 445 mg phenanthrene/kg and sampled after 21 wk. Pyrene-degraders were enumerated using a modified plate count procedure. Selected degraders were analyzed by fatty acid methyl ester analysis (FAME) and compared with Mycobacterium sp. PYR-1 using principal component analysis (PCA). In the pyrene experiment, degraders increased from undetectable in the uncontaminated soil to 7.09 log10 degraders/g in the contaminated soil. In the pyrene+phenanthrene experiment, degrader numbers also seemed to increase in the contaminated compared to the uncontaminated soil.
Most of the degraders were not identified by FAME, but PCA of the FAME data indicated that the majority of degraders from both contaminated soils were similar to Mycobacterium sp. PYR-1. The results indicate that Captina silt loam can develop an effective pyrene-degrader population under the tested conditions.
Impacts
Using plants to remediate contaminated soils offers an economic and environmentally friendly alternative to traditional disposal methods. Our studies have evaluated plant growth characteristics and microbial populations in contaminated soil and have shown that plants can increase the number of contaminant-degraders in soil around plant roots.
Publications
- Reynolds, C.M. and D.C. Wolf. 1999. Microbial based strategies for assessing rhizosphere-enhanced phytoremediation. p. 125-135. In Environmental Technology Advancement Directorate (ETAD) of Environment Canada - Phytoremediation Technical Seminar. 31 May - 1 June 1999. Calgary, Alberta, Canada.
- Reynolds, C.M., D.C. Wolf, T.J. Gentry, L.B. Perry, C.S. Pidgeon, B.A. Koenen, H.B. Rogers, and C.A. Beyrouty. 1999. Plant enhancement of indigenous soil micro-organisms: A low-cost treatment of contaminated soils. Polar Rec. 35(192):33-40.
- Krutz, L.J., C.A. Beyrouty, D.C. Wolf, and E.E. Gbur. 1999. Influence of plant species on pyrene dissipation from the rhizosphere. p. 344. In 1999 Agronomy abstracts. ASA, Madison, WI.
- Nichols, H.L., D.C. Wolf, C.M. Reynolds, and B.A. Koenen. 1999. Microbial populations in petroleum-contaminated arctic, sub-arctic, and temperate soils. p. 234. In 1999 Agronomy abstracts. ASA, Madison, WI.
- Nichols, H.L., D.C. Wolf, C.M. Reynolds, L.B. Perry, and C.S. Pidgeon. Microbial populations in petroleum-contaminated soils. p. 7. In Abstracts of technical papers, 1999 annu. meet., S. Branch, ASA, Memphis, TN. 30 Jan.-3 Feb. 1999. ASA, Madison, WI.
- Reynolds, C.M., H. Nichols, L.B. Perry, C.S. Pidgeon, K. McCarthy, L. Karr, J. Karrh, K. Foley, D. Pelton, B.A. Koenen, and D.C. Wolf. 1999. Preliminary results from field demonstrations of rhizosphere-enhanced degradation of organic-contaminated soils in cold regions. In Ninth Annual West Coast Conf. on Contaminated Soils and Groundwater. 8-11 March 1999. Oxnard, CA.
- Reynolds, C.M., D.M. Sylvia, T. Olexa, P.G. Hartel, T.J. Gentry, and D.C. Wolf. 1999. Mycorrhizal colonization of ryegrass in contaminated soils. Special phytoremediation session at the Ninth Annual West Coast Conf. on Contaminated Soils and Groundwater March 8-11, 1999, at Oxnard, CA.
- Reynolds, C.M., C.S. Pidgeon, L.B. Perry and B.A. Koenen, D. Pelton, H.L. Nichols and D.C. Wolf. 1999. Using microbial community structure changes to evaluate phytoremediation. Fifth International Symposium, In-Situ and Onsite Bioreclamation. April 19-22, San Diego CA.
- Thoma, G.J., M.L. Bowen, C.A. Beyrouty, and D.C. Wolf. 1999. An L-systems approach to rhizosphere volume estimation. p. 235. In 1999 Agronomy abstracts. ASA, Madison, WI.
- Thoma, G.J., M.L. Bowen, C.A. Beyrouty, and D.C. Wolf. 1999. An L-systems approach to rhizosphere volume estimation. p. 125. In K.L. Sublette, G.J. Thoma, and T.J. Ward (ed.) Sixth International Petroleum Environ. Conf., Houston, TX. 16-18 Nov. 1999.
- Thoma, G.J., T.J. Gentry, L.J. Krutz, D.C. Wolf, C.A. Beyrouty, and C.M. Reynolds. 1999. Phytoremediation of petroleum-contaminated soils. p. 123. In K.L. Sublette, G.J. Thoma, and T.J. Ward (ed.) Sixth International Petroleum Environ. Conf., Houston, TX. 16-18 Nov. 1999.
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Progress 01/01/98 to 12/31/98
Outputs
Microbial degradation in soil is the main pathway for removal of polycyclic aromatic hydrocarbons (PAHs), a toxic and carcinogenic portion of many organic contaminants. To increase understanding of the microbial processes in PAH-contaminated soil, pyrene, a four-ring PAH, was added to a Captina silt loam (fine-silty, siliceous, mesic Typic Fragiudults) at 0 and 2000 mg/kg dry soil. Soil was incubated in sterile glass jars and sampled after 10 and 61 wk. Pyrene levels in soil were determined with gas chromatography. Bacteria, fungi, and actinomycetes were enumerated by plate count techniques. Pyrene degrader numbers were determined at 61 wk with a modified plate count procedure. No significant reduction in pyrene concentration occurred by 10 wk with 96.5% recovered, but by 61 wk <1% was recovered. Pyrene had no effect on bacterial or fungal numbers at either sampling time. Numbers of actinomycetes were not affected at 10 wk but increased at 61 wk with 5.3 and 6.0 log10
CFU/g dry soil in uncontaminated and contaminated soils, respectively. By 61 wk, pyrene degraders increased from undetectable in uncontaminated soil to 7.1 log10 CFU/g dry soil in contaminated soil. These results indicate that the Captina silt loam contained microorganisms capable of degrading pyrene but, under study conditions, required >10 wk for an effective degrader population to develop.
Impacts
(N/A)
Publications
- Gentry, T.J., Wolf, D.C., Pidgeon, C.S., Reynolds, C.M., and Fuhrman, J.J. 1998. Enumeration of pyrene-degrading microorganisms in contaminated soil. p. 224. In Agronomy abstracts. ASA, Madison, WI.
- Pulley, H.J., Beyrouty, C.A. and Wolf, D.C. 1998. Growth response of wetland plants to TNT contamination. p. 338. In Agronomy abstracts. ASA, Madison, WI.
- Reynolds, C.M., Pidgeon, C.S., Perry, L.B., Gentry, T.J., and Wolf, D.C. 1998. Rhizosphere-enhanced benefits for remediating recalcitrant petroleum compounds. 14th Annual Conf. on Contaminated Soils, Amherst, MA. 19-22 Oct. 1998.
- Gentry, T.J., Wolf, D.C., Pidgeon, C.S., Perry, L.B., Reynolds, C.M., and Beyrouty, C.A. 1998. Influence of pyrene on soil microbial populations. p. 8. In Southern Branch Agronomy abstracts. ASA, Madison, WI.
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Progress 01/01/97 to 12/31/97
Outputs
The commercial application of bioremediation technologies requires better understanding of how soil properties influence bioremediation and sample analysis accuracy. Fifty-gram samples of two soils, a silt loam and a fine sandy loam were placed in glass beakers and contaminated at a rate of 2000 mg/kg dry soil with a mixture of six organic chemicals. Prior to the addition of the chemicals, one-half of the beakers were autoclaved and treated with HgCl2 at a rate of 2000 mg/kg dry soil to inhibit biological activity. Uncontaminated controls were included. Beakers were sampled on day 0, day 1, and every third day through day 28. Samples were extracted and analyzed using a GC/FID. 2,2- dimethyl 4,n-propylbenzene and cis-decahydronaphthalene were volatile, disappearing from all samples by day 7. Rate constants for hexadecane, phenanthrene, and pyrene in all soil samples that were autoclaved and treated with HgCl2 were not significantly different from zero, indicating no
disappearance of these chemicals. In the non-sterilized soil samples, disappearance of hexadecane from both soils and phenanthrene from the fine sandy loam followed first order kinetics, with rate constants of 0.074/d, 0.102/d, and 0.081/d, respectively. In contrast, the rate constants for pyrene in both soils and phenanthrene in the silt loam were not different from zero. Phenanthrene had significantly different rate constants between soils.
Impacts
(N/A)
Publications
- NICHOLS, T.D., D.C. WOLF, H.B. ROGERS, C.A. BEYROUTY, AND C.M. REYNOLDS. 1997. RHIZOSPHERE MICROBIAL POPULATIONS IN CONTAMINATED SOILS. WATER, AIR, AND SOIL POLLUTION. 95:165-178.
- REYNOLDS, C.M., T.J. GENTRY, D.C. WOLF, L.B. PERRY, C.S. PIDGEON, H.B. ROGERS, AND C.A. BEYROUTY. 1997. PHYTOREMEDIATION OF HYDROCARBON-CONTAMINATED SOILS. IN PROC. 4TH ANNUAL INT. PETROLEUM ENVIRONMENTAL CONF., SAN ANTONIO, TX. 9-12 SEPT. 1997. (IN PRESS).
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Progress 01/01/96 to 12/30/96
Outputs
Polycyclic aromatic hydrocarbons (PAHs) are a toxic and recalcitrant portion of many organic soil contaminants. Increased understanding of the PAH impact on soil microorganisms may lead to enhanced bioremediation of contaminated soils. To assess the influence of PAHs on selected soil microbial populations, pyrene, a four-ring PAH, was added to Captina silt loam (fine-silty, siliceous, mesic Typic Fragiudults) at a rate of 0 or 2000 mg/kg dry soil. Soil was placed into sterile glass jars, planted with alfalfa or bahiagrass, and incubated in a growth chamber 10 wk. Nonrhizosphere (no-plant) controls were included. Numbers of bacteria, actinomycetes, and fungi were determined by plate count technique using tryptic soy agar, starch casein agar, and Martin's medium, respectively. Pyrene had no effect on the number of bacteria, actinomycetes, or fungi compared to the control. Numbers of bacteria and actinomycetes were higher in the alfalfa and bahiagrass rhizospheres than
in the nonrhizosphere soil. The bahiagrass rhizosphere contained a higher number of fungi than the nonrhizosphere soil and alfalfa rhizosphere. Addition of pyrene decreased plant shoot and root dry weights, root lengths, and root surface areas. These results indicate that pyrene at a rate of 2000 mg/kg dry soil did not affect microbial numbers but did decrease measured plant growth parameters. Also, microbial numbers were increased in the rhizosphere.
Impacts
(N/A)
Publications
- ROGERS, H.B., BEYROUTY, C.A., NICHOLS, T.D., WOLF, D.C. AND REYNOLDS, C.M. 1996.SELECTION OF COLD-TOLERANT PLANTS FOR GROWTH IN SOILS CONTAMINATED WITH ORGANICS. J. SOIL CONTAM. 5:171-186.
- BEYROUTY, C.A., REYNOLDS, C.M., ROGERS, H.B., NICHOLS, T.D. AND WOLF, D.C. 1996.PLANT AND MICROBIAL INFLUENCE ON BIOREMEDIATION OF CONTAMINATED SOILS. IN PROC. 3RD INT. PET. ENVIRON.
- CONF., ALBUQUERQUE, NM. 24-27 SEPT. 1996.
- GENTRY, T.J., WOLF, D.C., REYNOLDS, C.M., ROGERS, H.B. AND BEYROUTY, C.A. 1996. PYRENE INFLUENCE ON SOIL MICROBIAL POPULATIONS. P. 229.
- IN AGRONOMY ABSTRACTS. ASA, MADISON, WI. ROGERS, H.B., BEYROUTY, C.A., WOLF, D.C., GENTRY, T.J. AND REYNOLDS, C.M. 1996. INFLUENCE OF SOILS ON DECOMPOSITION RATES OF ORGANIC CHEMICALS: IMPLICATIONS FORBIOREMEDIATION. P. 343.
- IN AGRONOMY ABSTRACTS. ASA, MADISON, WI. ROGERS, H.B., BEYROUTY, C.A., WOLF, D.C., GENTRY, T.J. AND REYNOLDS, C.M. 1996. INFLUENCE OF SOILS ON DECOMPOSITION RATES OF ORGANIC CHEMICALS: IMPLICATIONS FORBIOREMEDIATION. PROC. CONTAMINATED SOILS. 21-24 OCT. 1996, AMHERST, MA.
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Progress 01/01/95 to 12/30/95
Outputs
A mixture of organic chemicals (MOC) containing equal molar amounts of benzoic acid, hexadecane, 2,2-dimethyl 4,n-propyl-benzene, phenanthrene, pyrene, and either cycloheptane or cis-decahydronaphthalene (cis-decalin) was applied to soil at rates of 0 to 8000 mg/kg. In a plant screening experiment, growth responses of four legume and five non-legume species were determined at 10 and 25deg.C. The MOC applied at 2000 mg/kg reduced growth of several species without resulting in significant seedling death. At 10deg.C, growth of alpine bluegrass (Poa alpina L.) in 1000 and 2000 mg MOC/kg soils increased by more than 185%. In a plant growth response experiment, alpine bluegrass and alfalfa (Medicago sativa L.) were grown in soil that had been contaminated at rates of 0 and 2000 mg MOC/kg. At 14 wk, shoot and root dry weights of alfalfa were 97% lower in the contaminated soil, while shoot dry weight, root dry weight, and root length of alpine bluegrass were 135, 235, and 268%
higher, respectively. Except for pyrene, <23% of the compounds comprising the MOC remained in the soil after 4 wk and <5% after 14 wk. The disappearance of the MOC was not significantly influenced by the presence of alfalfa or alpine bluegrass.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
Enhanced microbial populations in the rhizosphere may increase bioremediation ofpetroleum contaminated soil. Growth response of five grass and four legume species was determined for a model petroleum hydrocarbon contaminant (MPC) at rates of 0 to 8000 mg/kg at 10 and 25deg.C. The MPC contained equal molar amounts of hexadecane, 2,2-dimethyl 4,n propylbenzene, phenanthrene, pyrene, and either cycloheptane or cis- decalin. MPC applied at 2000 mg/kg to several grass and legume species stressed shoot growth without significant seedling death. In a bioremediation study, bluegrass (Poa pratensis L.), and alfalfa (Medicago sativa L.) were grown in soil containing 0 and 2000 mg MPC/kg. Shoot and root dry weight of alfalfa and shoot dry weight of bluegrass were 97% lower and 37% higher, respectively, 14 wks after application of 2000 mg MPC/kg soil. Except for pyrene, 23% or less of the four other compounds in the MPC remained in the soil after 4 wks and 4% or less after 14 wks.
Pyrene recovery was greater than 56% throughout the experiment. Bacteria and hydrocarbon degrader numbers were greater in MPC-contaminated rhizosphere soil than in contaminated bulk or non-contaminated bulk and rhizosphere soil. Thus, plants and their associated rhizosphere microorganisms may enhance bioremediation of petroleum contaminated soils.
Impacts
(N/A)
Publications
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