Progress 10/01/13 to 09/30/14
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? This project provided training and professional development for a postdoctoral student and research experience for an undergraduate intern student participating in a summer research intern program. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals? We will continue research similar to and building upon that reported for the past year (W2082 objective 1). We also hope to complete a project associated with W2082 objectives 2 and 3.
Impacts
What was accomplished under these goals?
The fourth year of this project continued focus on the use of microbial isolates to remediate heavy metal(loid) (HM)-contaminated soil, promote plant growth and produce bioenergy crops (relative to multistate W2082 objective 1). This research is part of an on-going collaboration with faculty and students at Chonbuk National University, Iksan, Republic of Korea. Vegetation is critical to stabilize and remediate mine tailing sites, but plant growth is often poor due to toxicity from HMs. Bacillus sp. strain JH 2-2, isolated from the rhizosphere of plants at a multi-metal contaminated mine site, has the potential to reduce highly toxic Cr(VI) to less toxic Cr(III) and promote plant growth by reducing Cr toxicity and by producing the growth-promoting hormone indoleacetic acid (IAA). The minimum inhibitory concentration of Cr(VI) to Bacillus sp. JH 2-2 was 1000 mg L-1 and the strain reduced 99% of 10 mg Cr(VI) L-1 to Cr(IV) within 24 h. Lower Cr(VI) stress (10 mg L-1) stimulated IAA production, but much less IAA was produced at 30 or 50 mg Cr(VI) L-1. Inoculation with Bacillus sp. JH 2-2 increased the length of Indian mustard (Brassica juncea L.) roots by 364% and stems by 735% in the presence of 10 mg Cr(VI) L-1 from those of uninoculated control plants. A second bacterial strain (JH 70-4), exhibiting plant growth-promoting IAA and 1-aminocyclopropane-1-carboxylate deaminase activity as well as heavy metal tolerance and Pb precipitation, was isolated from heavy metal-contaminated soil at an abandoned mine site. The bacterium was identified as Pseudomonas fluorescens based on 16S rDNA sequencing. The JH 70-4 strain induced precipitation of Pb as PbS nanoparticles, confirmed by x-ray diffraction. Solution pH, incubation time, and Pb concentration influenced removal and PbS formation. Inoculating contaminated soil with JH 70-4 decreased Pb availability; exchangeable Pb decreased while organic- and sulfide-bound Pb increased. The Toxicity Characteristic Leaching Procedure (TCLP) showed a 65% decrease in Pb in leachate 60 d after inoculating soil with JH 70-4. Shoot and root lengths of Sudan grass (Sorghum sudanese (Piper) Stapf) grown in inoculated soil were greater than in uninoculated soil. A non-symbiotic endophytic fungus, Trichoderma sp. PDR1-7, isolated from Pb-contaminated mine tailing soil, similarly exhibited both high tolerance to HMs and desirable plant growth-promoting characteristics. PDR1-7 promoted HM solubilization in mine tailing soil and removed significant amounts of Pb and other HMs from liquid media containing single and multiple metals. Pb removal efficiency increased with initial pH from 4 to 6 and with Pb concentration from 100 to 125 mg L−1. Inoculating soil with PDR1-7 significantly increased nutrient availability and seedling growth, chlorophyll and protein contents, as well as antioxidative enzyme (superoxide dismutase) activity in Scots pine (Pinus sylvestris L.). A decrease in malondialdehyde indicated less oxidative stress. HM concentrations were much higher in roots when PDR1-7 was present. These research findings suggest: (a) the potential use of Bacillus sp. JH 2-2 to promote phytoremediation of soil contaminated with Cr(VI), (b) microbial Pb fixation is a viable strategy for remediating soil and promoting plant growth for phytostabilization of contaminated sites, and (c) the utility of Trichoderma sp. PDR1-7 for pine reforestation and phytoremediation of Pb-contaminated soil.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Babu, A.G., P.J. Shea, and B-T. Oh. 2014. Trichoderma sp. PDR1-7 promotes Pinus sylvestris reforestation of lead-contaminated mine tailing sites. Science of the Total Environment 476-477:561-567.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Babu, A.G., J. Shim, K-S. Bang, P.J. Shea, and B-T. Oh. 2014. Trichoderma virens PDR-28: A heavy metal tolerant and plant growth-promoting fungus for remediation and bioenergy crop production on mine tailing soil. Journal of Environmental Management 132:129-134.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Babu, A.G., J. Shim, P.J. Shea, and B-T. Oh. 2014. Penicillium aculeatum PDR-4 and Trichoderma sp. PDR-16 promote phytoremediation of mine tailing soil and bioenergy production with sorghum-sudangrass. Ecological Engineering 69:186-191.
- Type:
Journal Articles
Status:
Published
Year Published:
2014
Citation:
Shim, J., A.G. Babu, P. Velmurugan, P.J. Shea, and B-T. Oh. 2014. Pseudomonas fluorescens JH-70-4 promotes Pb stabilization and early seedling growth of Sudan grass in contaminated mining site soil. Environmental Technology 35:2589-2596.
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2014
Citation:
Shim, J., J-W. Kim, P.J. Shea, and B-T. Oh. 2014. IAA production by Bacillus sp. JH2-2 promotes Indian mustard growth in the presence of hexavalent chromium. Journal of Basic Microbiology (In press)
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Progress 10/01/12 to 09/30/13
Outputs
Target Audience:
Nothing Reported
Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? This project provided training and professional development for a postdoctoral student. How have the results been disseminated to communities of interest?
Nothing Reported
What do you plan to do during the next reporting period to accomplish the goals? We will continue research similar toand building on that reported for the past year.
Impacts
What was accomplished under these goals?
The focus of the third year of this project was the use of microbial isolates in conjunction with sorghum-sudangrass and maize as bioenergy crops to stabilize and remediate heavy metal(loid) (HM)-contaminated soil. This research is part of an on-going collaboration with faculty and students at Chonbuk National University, Iksan, Republic of Korea. Vegetation is critical to stabilize and remediate mine tailing sites, but plant growth is often poor due to toxicity from HMs. Fungi can facilitate phytoremediation and restore productivity to mine tailing and other soils containing HMs. Penicillium aculeatum PDR-4 and Trichoderma sp. PDR-16, isolated from the rhizosphere of Korean pine at an abandoned mine site, exhibited high HM tolerance and plant growth-promoting characteristics. The isolates increased available P in a 1:1 (w/w) mixture of soil and liquid media by 14-43% and the bioavailability of As, Cu, Pb and Zn was also increased. Both isolates exhibited phosphatase, phytase and siderophore activity.ACC deaminase activity was greater inPDR-16 than inPDR-4;IAA was produced byPDR-4 but not by PDR-16. Sorghum-sudangrass produced 37-95% more aboveground dry biomass and contained 74-128% more chlorophyll in inoculated soil. In soil containing both isolates, HM concentrations increased in roots by 109% (As), 39% (Cu), 50% (Pb) and 38% (Zn), and in shoots by 72% (As), 69% (Pb) and 82% (Zn) from those of control plants (Cu concentration did not increase in shoots). HM bioavailability and available soil P, as well as plant biomass, chlorophyll content and plant As, Pb and Zn concentrations were highest in soil inoculated with both fungi. Results suggest that inoculating soil with PDR-4 and PDR-16 will be beneficial for phytoremediation and production of sorghum-sudangrass as a bioenergy crop on HM-contaminated soils. In a related study, another heavy metal-tolerant fungus, Trichoderma virens PDR-28, was isolated and evaluated for use in remediating mine tailing soil and for biomass production. PDR-28 exhibited plant growth-promoting traits, including ACC deaminase, acid phosphatase and phytase activity, siderophore production, and P solubilization. Soil inoculated with the fungus solubilized HMs and reduced residual concentrations by 24% (As), 31% (Cd), 3% (Cu), 9% (Pb), and 24% (Zn) at a 4:1 (w/v) soil:culture media ratio. PDR-28 had a high capacity to remove HMs (Pb > Cd > As > Zn > Cu) from liquid media containing single and multiple metals. Inoculating contaminated soil with the fungus significantly increased the dry biomass of maize roots (64%) and shoots (56%). Chlorophyll, total soluble sugars (reducing and nonreducing), starch, and protein contents were increased by 46, 28, 30, and 29%, respectively, compared to plants grown in uninoculated soil. Importantly, inoculation with PDR-28 enhanced HM accumulation in the fungus would be beneficial for phytoremediation of soil contaminated with HMs and useful for producing maize as a bioenergy crop in those areas.
Publications
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Progress 10/01/11 to 09/30/12
Outputs
OUTPUTS: The second project year focused on adaptation of a watershed vulnerability model to the field scale (associated with multistate objective 2). Identifying areas vulnerable to off-site agrichemical movement and surface and ground water contamination through conventional data collection is labor-intensive, costly and time-consuming. To promote efficient pesticide use and protect water resources, a process-based index model was previously developed to assess landscape vulnerability to pesticide runoff and leaching. The model is based on the physicochemical properties of the pesticide [including adsorption (organic carbon partition coefficient), relative persistence (half-life), and susceptibility to abiotic hydrolysis] and hydrologic/landscape characteristics [including the soil saturated hydraulic conductivity, organic matter, clay content, pH, depth to restrictive layer, soil texture, clay mineralogy, whole fraction erodibility, drainage class, flooding frequency and slope]. The watershed-scale (regional) model incorporates pesticide dissipation and hydrologic functions and utilizes the 1:24,000-scale USDA-NRCS Soil Survey Geographic Database (SSURGO). Because mitigating contamination of surface and ground waters requires implementation of best management practices (BMPs), the model was adapted to the field scale using data from a research site in Boone County, Missouri. Available field-scale data included saturated hydraulic conductivity, pH, organic matter, 5 x 5 m resolution elevation from which slope was derived, and Agricultural Policy/Environmental eXtender (APEX)-modeled daily moisture content. To accommodate the impact of a restrictive claypan layer, three modifiers were tested based on water storage capacity above the claypan. Mathematical functions were imported into ArcGIS and maps were generated showing the relative potential for off-site movement of pesticides across the Missouri field. Atrazine loss in runoff projected by a quantitative application of the model was compared with measurements made at the field outlet for odd (corn) years from 1993 to 2001. A poster on this work was presented at the 2011 American Society of Agronomy meeting. PARTICIPANTS: Patrick J. Shea is the PI for the Nebraska project. The field-scale modeling was conducted by M.S. student Atefeh Hosseini, who graduated in August, 2012. Project contributors include Maribeth Milner and Richard Ferguson (Dept. of Agronomy and Horticulture, UNL); Mark Bernards (Western Illinois University); Robert N. Lerch and Claire Baffaut (USDA-ARS, Columbia, MO). TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The sensitivity of the field-scale vulnerability model to soil physiochemical properties and topographical position was demonstrated. A quantitative application of the model using five years of atrazine transport data demonstrated its capability to estimate runoff losses, although model estimates exceeded field measurements. Days since application, and model-estimated amounts of "unbound atrazine" and "unbound atrazine prone to runoff" were highly correlated to atrazine measured in runoff from the field. Because the effective half-life function currently used in the chemistry component of the model inflates atrazine half-life, adjusting that function would likely improve the model. Microbial adaptation has been shown to accelerate atrazine degradation in fields receiving multiple years of application and this can dramatically reduce its half-life. Adjustment of biotic degradation half-life should produce closer agreement between model-generated and field-measured herbicide in runoff water. The hydrologic component of the model could also be improved by integrating BMPs and rainfall intensity. The field-scale and regional models can help identify vulnerable areas within agricultural fields and watersheds to target and prioritize sites for implementation of best management practices and regulatory strategies that effectively address water quality issues. Validation of the model was limited to one Missouri field with soil layers restrictive to water flow (claypans). To ensure the capacity of the model to accurately delineate areas vulnerable to pesticide movement within a field and estimate losses, further testing should be conducted on fields differing from the study area and where the required data are available.
Publications
- Dhakal, K. 2011. Atrazine runoff in the Blue River Basin: Geomorphology, rainfall, and agronomic practices. M.S. Thesis, University of Nebraska-Lincoln. 125 p.
- Hosseini, A. 2012. Field-scale adaption of a process-based index model for landscape vulnerability to surface and ground water contamination. M.S. Thesis. University of Nebraska-Lincoln. 110 p.
- Hosseini, A., Milner, M., Lerch, R.N., Bernards, M.L., and Shea, P.J. 2011. Field-scale adaption of a process-based index model for landscape vulnerability to surface and ground water contamination. Am. Soc. Agronomy-Crop Sci. Soc. Am.-Soil Sci. Soc. Am., 10/17/11 Abstract 34-7: http://a-c-s.confex.com/crops/2011am/webprogram/Paper67726.html
- Wei, H-R., M.G. Rhoades, and Shea, P.J. 2011. Formation, adsorption, and stability of N-nitrosoatrazine in water and soil. In: It's All in the Water: Studies of Materials and Conditions in Fresh and Salt Water Bodies, M.A. Benvenuto, ed. American Chemical Society Symposium Series. Washington, DC: American Chemical Society.
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Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: The first project year included (a) the soil adsorption-desorption behavior of N-nitrosoatrazine (NNAT), formed from reaction of atrazine with nitrite under acidic conditions (associated with multistate objective 1), (b) initial steps to adapt of a watershed vulnerability model to the field scale (associated with multistate objective 2), and (c) identification of variables affecting atrazine runoff from subwatersheds (associated with multistate objective 3). In (a), which complements NEB-38-069, the sorption characteristics of NNAT were determined by adding 2 g air-dried Aksarben soil to Teflon tubes with 10 mL deionized, distilled water and 12 ug NNAT (6 mg/kg Aksarben soil). The pH was adjusted to 3-8, and tubes were shaken for 24 h at 25 C. The suspensions were centrifuged and concentrations of NNAT in the supernatant were determined by HPLC. Desorption was determined by decanting the remaining supernatant, adding water to the soil, shaking for 24 h at 25 C, and determining the concentrations of the compounds by HPLC. The experiment was repeated with atrazine for comparison with NNAT. Adsorption and desorption distribution coefficients (Kd) and organic carbon partition coefficient (Koc) were calculated. Adsorption experiments were also conducted with bentonite clay and clay treated with dodecyltrimethylammonium bromide (DDTMA) to simulate lipid-coated clays that may be present in sediments or tannic acid (TAC) to simulate clays coated with polar organic functional groups. Analysis of atrazine and nitrosoatrazine were by HPLC with UV detection (atrazine at 235 nm; nitrosoatrazine at 246 nm). A poster on this work was presented at the Spring 2011 American Chemical Society meeting. In (b), the components of a watershed-scale vulnerability model (developed in a USDA-NIWQP project) were analyzed, converted to a GIS, and adapted to the field scale using SSURGO and field data, with a goal of finding the best resolution for raster maps. Model output was generated for the acid-sensitive herbicide, atrazine, on the day of application and 7 days after application for a 35-ha field in north-central Missouri, an intensely row-cropped agricultural field with claypan soils located in Major Land Resource Area 113. A poster is being presented at the October 2011 Soil Science Society of America meeting. For (c), the impacts of corn and sorghum planting progress (indicating atrazine application), rainfall, antecedent soil water content, and the presence of a soil surface restrictive layer on stream-measured weekly atrazine load for 1997-2004 were determined for independent subwatersheds of the NE-KS Blue River Basin. Analysis of covariance was conducted from day 110 when about 10% of the corn was planted to day 170 when 90% of the sorghum was planted. An oral presentation on this project was given at the 2011 Weed Science Society of America meeting. PARTICIPANTS: Patrick J. Shea is the PI for the Nebraska project. Nitrosoatrazine sorption studies (objective 1) were conducted by M.S. student Hsin-Ro Wei (who graduated in May, 2011), with assistance provided by M. Rhoades (UNL School of Natural Resources) and D. Snow (UNL Water Sciences Laboratory). Field-scale modeling (objective 2) is being conducted by M.S. student Atefeh Hosseini, expected to graduate in May, 2012. The atrazine runoff loading studies (objective 3) were conducted by M.S. student Kundan Dhakal, who is graduating in December, 2011. M. Bernards (formerly UNL, now Western Illinois University), M. Milner (UNL Dept. Agronomy and Horticulture), R. Lerch and C. Baffaut (USDA-ARS, Columbia, MO), and P. Barnes (Kansas State University) are contributing to aspects of objectives 2 and 3. TARGET AUDIENCES: Target audiences for the findings associated with multistate objectives 2 and 3 include farmers, agencies, and extension workers (targeting of best management practices). PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
In NNAT adsorption- desorption studies (a), adsorption Kd and Koc values indicated greater adsorption of NNAT (average Kd = 5.93; Koc = 495) than atrazine (average Kd = 2.71; Koc = 123) in Aksarben silty clay loam at agronomic pH levels. Larger desorption Kd values indicated more hysteresis of NNAT than atrazine. Soil texture affected NNAT and atrazine adsorption in soil, with less adsorption of NNAT and atrazine on the Valentine sand than on Aksarben silt clay loam and Rosebud silt loam soils. In bentonite clay, the Kd for NNAT was larger than for atrazine. No NNAT or atrazine was detected in solution after equilibrating those compounds with bentonite clay treated with DDTMA or TAC, indicating that adsorption was further increased by coating the clay with organic material. Information obtained from this research is important when evaluating atrazine fate and impacts in soil-water environment. The relatively high affinity for clay and organic matter would reduce NNAT availability for further movement, but it may persist in some ground waters. In (b), field-scale adaptation of a watershed vulnerability model, the initial model showed how acid-catalyzed hydrolysis of atrazine would reduce vulnerability to solution runoff in the north part of a Missouri test field. Vulnerability to leaching in the test field was comparatively lower than to solution runoff. An early version of the watershed model had overpredicted leaching vulnerability due to the presence of claypans in the Missouri study area. Because a claypan is not a diagnostic horizon, identification criteria for a surface restrictive layer were developed based upon the Nebraska Rainwater Basins and Missouri claypans. A runoff penalty (which increases vulnerability) was created based on the large pore volume (saturated - 0.33 bar moisture) above the clay restrictive layer or depth to free water, whichever is shallower. Using these criteria, a clay restrictive layer was identified in the southern Blue River Basin, an area with atrazine runoff problems. By adapting the watershed model to the field scale, we can identify locations that contribute most to agrichemical loss, so appropriate best management practices (BMPs) can be implemented. In (c), variables affecting atrazine runoff, analysis of atrazine monitoring data showed maximum loading after most of the corn had been planted but during sorghum planting from mid-May to early June, immediately following multiple rainfall events that saturated the soil profile and caused runoff from fields. Analysis of covariance showed rainfall was the most significant factor associated with atrazine loading, but soil water content, corn and sorghum planting progress, and the presence of a soil surface restrictive layer were also important. Project results provide decision support to farmers, agencies, extension workers, and scientists for targeting of best management practices.
Publications
- Dhakal, K., Bernards, M.L., Milner, M., Barnes, P.L., and Shea, P.J. 2011. Contributions of agronomic practices, precipitation patterns, and landscape vulnerability to atrazine load in the Big Blue River Basin. Weed Science Society Abstract 157: http://wssaabstracts.com/public/abstract-157.html.
- Wei, H-R. 2011. Formation, adsorption and stability of N-nitrosoatrazine in water and soil. M.S. Thesis, University of Nebraska-Lincoln. 76 p.
- Wei, H-R., Rhoades, M.G., and Shea, P.J. 2011. Nitrosoatrazine formation and behavior in water and soil. American Chemical Society, 241st National Meeting, Anaheim, CA. Abstract 198. http://abstracts.acs.org/chem/241nm/program/view.php.
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