Progress 11/15/04 to 11/14/08
Outputs
OUTPUTS: Outputs of our project include the 25 refereed publications listed below, which we have also summarized in a review paper ("Comprehensive study of organic contaminant adsorption by clays: Methodologies and mechanisms") that has been accepted for publication and should appear in the literature during 2010. Furthermore, we have given in excess of 50 talks at scientific meetings around the world in order to publicize the research that USDA has sponsored here. Members of the grant team have helped organize five symposia related to sorption of organic solutes by clay minerals. In addition, we have filed a patent application using ideas generated from this project (the patent details how changes in fertilizer regime could be used to promote either binding or release of toxic organics when establishing plants for phytoremediation). As faculty members, we have incorporated the new knowledge generated by this research into our teaching at both the graduate and undergraduate levels. Finally, eleven graduate students and five postdocs (plus two more postdocs who had initially been graduate students on the project) have participated in this research. Through their efforts, we have expanded the analytical technologies (experimental, molecular modeling, and chemical speciation modeling) available for studying clay-organic interactions, and they are taking the new knowledge and analytical capabilities with them to their new positions. PARTICIPANTS: Co-PIs: Brian J. Teppen, Michigan State University Stephen A. Boyd, Michigan State University Cliff T. Johnston, Purdue University David A. Laird, USDA-ARS National Soil Tilth Laboratory and Iowa State University Hui Li, Michigan State University Other faculty: Michael Thompson, Iowa State University Clayton L. Rugh, Michigan State University Postdoctoral Associates: Wenlu Song, Michigan State University Cheng Gu, Michigan State University Vaneet Aggarwal, Michigan State University Michael Roberts, Michigan State University Hui Li, Michigan State University G.S. Premachandra, Purdue University Yao-Ying Chien, Michigan State University Graduate Students: Cun Liu, Michigan State University Kiran Rana, Purdue University Cuiping Wang, Michigan State University Jason Ding, Michigan State University Mark Chappell, Iowa State University Simone Charles, Michigan State University Tanya Pereira, Michigan State University and Iowa State University Vaneet Aggarwal, Michigan State University Michael G. Roberts, Michigan State University Maurilio F. de Oliveira, Purdue University Jacqueline Arroyo, Michigan State University TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
This research, sponsored by USDA, has led to a change in knowledge in which the broader soil science community is becoming more aware of the situations in which clay minerals dictate the fates of trace organics in soil and water. We have created new fundamental and applied knowledge significant enough to comprise 25 refereed publications emanating from this project. Our papers on clay-organic interactions are being cited some 200 times per year by other researchers, indicating that they are using our results to inform their own research techniques, data interpretation, policy knowledge, and decision-making. Presumably, the dissemination of our results will slowly change the behavior and practices of people, as they begin to seriously consider clay minerals as possible sinks and sources of organic pollutants. Examples might include the use of the patent we have filed, other application and actual use of our fundamental knowledge, adoption of our new or improved analytical techniques, or direct application of information from our publications. More broadly, we have actively participated in development of our principal discipline in this project, soil chemistry. We have certainly worked to change the orthodox notion that organic matter is the sole soil component that controls the fates of nonionic organic solutes in soil/water systems, and we have had an impact as the role of clay minerals becomes more broadly understood. Through our mentoring of students and postdocs, we have helped to develop the human resources to carry on such research, and we have contributed to the physical, institutional, and information resources that improve research infrastructure at at least four universities. We have published our results so that they may be applied to pesticide transport and fate by those who are trying to manage our nation's food supply in a sustainable manner, and by those who are attempting to protect water quality and the general environment.
Publications
- Liu, C., Li, H., Teppen, B.J., Johnston, C.T., and Boyd, S.A. 2009. Mechanisms Associated with the High Adsorption of Dibenzo-p-dioxin from Water by Smectite Clays. Environmental Science & Technology 43:2777-2783.
- Rana, K., Boyd, S.A., Teppen, B.J., Li, H., Liu, C., and Johnston, C.T. 2009. Probing the microscopic hydrophobicity of smectite surfaces. A vibrational spectroscopic study of dibenzo-p-dioxin sorption to smectite. Physical Chemistry Chemical Physics 11:2976-2985.
- Wang, C.P., Ding, Y.J., Teppen, B.J., Boyd, S.A., Song, C.Y., and Li, H. 2009. Role of Interlayer Hydration in Lincomycin Sorption by Smectite Clays. Environmental Science & Technology 43:6171-6176.
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Progress 11/15/06 to 11/14/07
Outputs
OUTPUTS: The year 2008 was a year of no-cost extension to our project. As such, we worked to wrap up experiments, simulations, and writing that were begun during the 2004-2007 originally proposed life of the grant. We made further progress during 2008 toward understanding how pesticide molecules interact with the clay mineral surfaces that dominate the surface areas of most soils. Our goals are to demonstrate mechanisms of interaction, because such knowledge enables rational management of agro-environmental systems. As we studied pesticide sorption during the life of this grant, we learned that, under certain circumstances, clay minerals can become enriched in organic solutes that are very nonpolar and are commonly thought to be excluded from the clay by competition with water. This is very interesting and led us to ideas that were the foundation for two other projects that study the intgeractions of clay minerals with dioxins. During 2008, we conducted experiments and/or simulations nearly every day, we disseminated our results with more than ten scientific talks in various venues, and we published three refereed papers. PARTICIPANTS: In mid-2007, we lost our postdoctoral associate (Vaneet Aggarwal) from this project when he took a permanent position elsewhere. As such, we have been slowed down from completing the work (especially some of the molecular simulations) and from writing up the integrative final papers. A graduate student from another project has assisted in carrying on the simulations, and also in performing a major hardware upgrade (using non-grant funds). The work was further slowed in October 2008 when, just after the hardware upgrade, purchase of the concomitant software upgrade was blocked because the new software license would have extended past the termination date of this grant. We need that software to perform some key simulations to help wrap up this project, so I am in process of applying for another no-cost extension to this project. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: In mid-2007, we lost our postdoctoral associate (Vaneet Aggarwal) from this project when he took a permanent position elsewhere. As such, we have been slowed down from completing the work (especially some of the molecular simulations) and from writing up the integrative final papers. A graduate student from another project has assisted in carrying on the simulations, and also in performing a major hardware upgrade (using non-grant funds). The work was further slowed in October 2008 when, just after the hardware upgrade, purchase of the concomitant software upgrade was blocked because the new software license would have extended past the termination date of this grant. We need that software to perform some key simulations to help wrap up this project, so I am in process of applying for another no-cost extension to this project.
Impacts
The year 2008 was a year of no-cost extension as we try to wrap up our project. Objective 1 is to examine nonionic organic compound (NOC) adsorption to smectites. We reported results for the adsorption of a systematic series of substituted benzenes to K- versus Ca-smectites. Some phenolic pesticides are strongly adsorbed by K-smectites even at pH values where the pesticide is anionic, and we showed that the anion sorbs to the clay as a K-pesticide neutral complex (Pereira et al., 2008). The formation and importance of such complexes is a significant impact of our project. Furthermore, when the phenol is chlorinated, we showed (Gu et al., 2008) that natural clays can catalyze the dimerization of the phenols to dioxins. We also reported the effects of K- versus Ca-clay minerals on the bioavailability and toxicity of NOCs in two papers by Roberts et al. (2007). Objective 2 is to determine the effects of smectite crystalline swelling and quasicrystal organization on NOC sorption, desorption, and aging. We published a paper (Pereira et al., 2008) that estimated the extent of smectite quasicrystal formation as a function of ionic strength in clay suspension and its effect on the adsorption of NOCs, which we have measured for the same systems. This paper showed, for the first time, that sorption of our model pesticides can cause previously expanded clay mineral interlayers to collapse and dehydrate in aqueous suspension. Another paper (Charles et al., 2008) explored how natural organic matter can block sites on the clay that might otherwise be available for pesticide adsorption. Objective 3 is to define the molecular mechanisms of pesticide-clay-water interactions through in-situ sorption and spectroscopic measurements of NOC-soil interactions coupled with molecular simulations. We continue to write up our improved understanding of the molecular interactions between pesticides and clay minerals in the presence of water by integrating our isotherms, spectra, simulations, and thermodynamic data.
Publications
- Charles, S., Teppen, B.J., Li, H., and Boyd, S.A. 2008. Fractional availability of smectite surfaces in soils for adsorption of nitroaromatic compounds in relation to soil and solute properties. Soil Science Society of America Journal 72:586-594.
- Pereira, T.R, Laird, D.A., Thompson, M.L., Johnston, C.T., Teppen, B.J., Li, H., and Boyd, S.A. 2008. Role of Smectite Quasicrystal Dynamics in Adsorption of Dinitrophenol. Soil Science Society of America Journal 72:347-354.
- Gu, C., Li, H., Teppen, B.J., and Boyd, S.A. 2008. Octachlorodibenzodioxin formation on Fe(III)-montmorillonite clay. Environmental Science and Technology 42:4758-4763.
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Progress 11/15/05 to 11/15/06
Outputs
During the second year of our project, we progressed toward all the objectives. Objective 1 is to build on our previous work and systematically examine nonionic organic compound (NOC) adsorption to K-, Ca-, and Al-smectites. We have been measuring the adsorption of a systematic series of substituted benzenes to those smectites, and reported preliminary results in two talks during the year. We reported the effect of a variety of cations on NOC sorption by smectite in a paper by Roberts et al. (2006). Objective 2 is to determine the effects of smectite crystalline swelling and quasicrystal organization on NOC sorption, desorption, and aging. We gathered data and have a manuscript in press on the use of UV-vis spectroscopy to estimate the extent of smectite quasicrystal formation as a function of ionic strength in clay suspension and its effect on the adsorption of NOCs, which we have measured for the same systems. During the year, we also published a related paper (Li
et al., 2006) on pesticide sorption to smectites as affected by ionic strength, which in turn affects quasicrystal organization. Objective 3 is to define the molecular mechanisms of pesticide-clay-water interactions through coupled in-situ sorption and spectroscopic measurements of pesticide-soil interactions. The overall goal of this objective is to develop an improved understanding of the molecular interactions between pesticides and related NOCs and representative soil constituents in the presence of water. We published (de Oliveira et al., 2005) a study of carbaryl (1-naphthyl-N-methyl-carbamate) sorption to smectites saturated with six different cations in which FTIR spectra were gathered for every point on each sorption isotherm. We also showed (Arroyo et al., 2005) that a degradation product of carbaryl, 1-naphthol, sorbs to smectites and can participate in redox reactions with the clay. We further delineated the hydrophobic contributions to NOC sorption by smectites in the two
papers by Aggarwal et al. (2006), where we again show that the less a smectite swells, the stronger it sorbs hydrophobic NOCs. Finally, we used our work on reference clays as a foundation to study NOC sorption by real soils in two papers by Charles et al. (2006). Natural soil organic matter (SOM) seems to partially inhibit NOC sorption by smectites, apparently because SOM itself either competes for smectite surfaces or otherwise blocks NOC access to those surfaces.
Impacts
The current project goal is to define the molecular mechanisms of pesticide-clay-water interactions. That is, to determine which pesticide properties and which soil clay properties contribute to the strong sorption of nonionic organic compounds (NOCs) and how those properties interact to cause sorption. The special foci of the current project are Ca- and Al-smectites, which are important in a practical sense because a) Smectite clays are common in agricultural soils and dominate the surface area of many soils, b) We have shown that sorption of many NOCs by smectites dwarfs their sorption by soil organic matter, c) Ca cations dominate the surfaces of smectites in the most agriculturally productive soils of the upper midwest, great plains, and northeast U.S., and d) Al cations dominate the surfaces of smectites in many soils of the southeastern U.S. Thus, if we can make a significant contribution to understanding the mechanisms of pesticide adsorption to Ca- and
Al-smectites, it will have a major impact on our understanding of pesticide adsorption and fate in agricultural soils of the U.S. Mechanistic understanding of adsorption is key to our ability to rationally manage new pesticide applications in a manner that sustains agricultural productivity without impairing environmental quality.
Publications
- de Oliveira, M.F., Johnston, C.T., Premachandra, G.S., Teppen, B.J., Li, H., Laird, D.A., Zhu, D.Q., and Boyd, S.A. 2005. Spectroscopic study of carbaryl sorption on smectite from aqueous suspension. Environmental Science & Technology 39:9123-9129.
- Charles, S.M., Li, H., Teppen, B.J., and Boyd, S.A. 2006. Quantifying the availability of clay surfaces in soils for adsorption of nitrocyanobenzene and diuron. Environmental Science & Technology 40:7751-7756.
- Li, H., Teppen, B.J., Laird, D.A., Johnston, C.T., and Boyd, S.A. 2006. Effects of increasing potassium chloride and calcium chloride ionic strength on pesticide sorption by potassium- and calcium-smectite. Soil Science Society of America Journal 70:1889-1895.
- Roberts, M.G., Li, H., Teppen, B.J., and Boyd, S.A. 2006. Sorption of nitroaromatics by ammonium- and organic ammonium-exchanged smectite: Shifts from adsorption/complexation to a partition-dominated process. Clays and Clay Minerals 54:426-434.
- Aggarwal, V., Li, H., Boyd, S.A., and Teppen, B.J. 2006. Enhanced sorption of trichloroethene by smectite clay exchanged with Cs+. Environmental Science & Technology 40:894-899.
- Aggarwal, V., Li, H., and Teppen, B.J. 2006. Triazine adsorption by saponite and beidellite clay minerals. Environmental Toxicology and Chemistry 25:392-399.
- Arroyo, L.J., Li, H., Teppen, B.J., Johnston, C.T., and Boyd, S.A. 2005. Oxidation of 1-naphthol coupled to reduction of structural Fe3+ in smectite. Clays and Clay Minerals 53:587-596.
- Charles, S.M., Teppen, B.J., Li, H., Laird, D.A., and Boyd, S.A. 2006. Exchangeable cation hydration properties strongly influence soil sorption of nitroaromatic compounds. Soil Science Society of America Journal 70:1470-1479.
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Progress 11/15/05 to 11/14/06
Outputs
During the third year of our project, we progressed toward the objectives but did not complete them so were granted a one-year extension. Objective 1 is to examine nonionic organic compound (NOC) adsorption to smectites. We measured the adsorption of a systematic series of substituted benzenes to K- versus Ca-smectites, and reported preliminary results during the year. Some phenolic pesticides are strongly adsorbed by K-smectites even at pH values where the pesticide is anionic, and we showed (Pereira et al., 2007) that the anion sorbs to the clay as a K-pesticide neutral complex. We also reported the effects of K- versus Ca-clay minerals on the bioavailability and toxicity of NOCs in two papers by Roberts et al. (2007). Objective 2 is to determine the effects of smectite crystalline swelling and quasicrystal organization on NOC sorption, desorption, and aging. We published a paper (Li et al., 2007) on the use of UV-vis spectroscopy to estimate the extent of smectite
quasicrystal formation as a function of ionic strength in clay suspension and its effect on the adsorption of NOCs, which we have measured for the same systems. This paper showed, for the first time, that sorption of our model pesticides can cause previously expanded clay mineral interlayers to collapse and dehydrate in aqueous suspension. Objective 3 is to define the molecular mechanisms of pesticide-clay-water interactions through in-situ sorption and spectroscopic measurements of NOC-soil interactions coupled with molecular simulations. The overall goal of this objective is to develop an improved understanding of the molecular interactions between pesticides and related NOCs and representative soil constituents in the presence of water. We published a study (Aggarwal et al., 2007) in which we developed new methods for estimating adsorption energies for pesticides, and tested those methods by simulating clay-NOC systems for which our group had previously gathered isotherms, spectra,
and thermodynamic data.
Impacts
The current project goal is to define the molecular mechanisms of pesticide-clay-water interactions. That is, to determine which pesticide properties and which soil clay properties contribute to the strong sorption of nonionic organic compounds (NOCs) and how those properties interact to cause sorption. The special foci of the current project are Ca- and Al-smectites, which are important in a practical sense because a) Smectite clays are common in agricultural soils and dominate the surface area of many soils, b) We have shown that sorption of many NOCs by smectites dwarfs their sorption by soil organic matter, c) Ca cations dominate the surfaces of smectites in the most agriculturally productive soils of the upper midwest, great plains, and northeast U.S., and d) Al cations dominate the surfaces of smectites in many soils of the southeastern U.S. Thus, if we can make a significant contribution to understanding the mechanisms of pesticide adsorption to Ca- and
Al-smectites, it will have a major impact on our understanding of pesticide adsorption and fate in agricultural soils of the U.S. Mechanistic understanding of adsorption is key to our ability to rationally manage new pesticide applications in a manner that sustains agricultural productivity without impairing environmental quality.
Publications
- Aggarwal, V., Chien, Y.Y., and Teppen, B.J. 2007. Molecular simulations to estimate thermodynamics for adsorption of polar organic solutes to montmorillonite. European Journal of Soil Science 58:945-957.
- Li, H., Pereira, T.R., Teppen, B.J., Laird, D.A., Johnston, C.T., and Boyd, S.A. 2007. Ionic strength-induced formation of smectite quasicrystals enhances nitroaromatic compound sorption. Environmental Science & Technology 41:1251-1256.
- Pereira, T.R., Laird, D.A., Johnston, C.T., Teppen, B.J., Li, H., and Boyd, S.A. 2007. Mechanism of dinitrophenol herbicide sorption by smectites in aqueous suspensions at varying pH. Soil Science Society of America Journal 71:1476-1481.
- Roberts, M.G., Rugh, C.L., Li, H., Teppen, B.J., and Boyd, S.A. 2007. Reducing bioavailability and phytotoxicity of 2,4-dinitrotoluene by sorption on K-smectite clay. Environmental Toxicology and Chemistry 26:358-360.
- Roberts, M.G., Rugh, C.L., Li, H., Teppen, B.J., and Boyd, S.A. 2007. Geochemical modulation of bioavailability and toxicity of nitroaromatic compounds to aquatic plants. Environmental Science & Technology 41:1641-1645.
- Teppen, B.J., and Aggarwal, V. 2007. Thermodynamics of organic cation exchange selectivity in smectites. Clays Clay Miner. 55:119-130.
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Progress 11/15/04 to 11/15/05
Outputs
During the first year of our project, we have made progress on all the objectives. Objective 1 is to build on our K-smectite work to systematically examine nonionic organic compound (NOC) adsorption to Ca- and Al-smectites. We have prepared K-, Ca-, and Al-saturated specimens of the low-charge Wyoming montmorillonite SWy-2 and the high-charge Arizona montmorillonite SAz-1. We are therefore poised to begin measuring the adsorption of a systematic series of substituted benzenes to those smectites. Objective 2 is to determine the effects of smectite crystalline swelling and quasicrystal organization on NOC sorption, desorption, and aging. We have gathered data, and have a manuscript in preparation, on the use of UV-vis spectroscopy to estimate the extent of smectite quasicrystal formation as a function of ionic strength in clay suspension and its effect on the adsorption of NOCs, which we have measured for the same systems. We have just published (Chappell et al., 2005)
the first measurements of smectite layer spacings in suspension that are directly coupled to NOC adsorption. These data show unequivocally that smaller smectite layer spacing, all else being equal, results in much larger adsorption of NOC by the smectite. Objective 3 is to define the molecular mechanisms of pesticide-clay-water interactions through coupled in-situ sorption and spectroscopic measurements of pesticide-soil interactions. The overall goal of this objective is to develop an improved understanding of the molecular interactions between pesticides and related nonionic organic compounds (NOCs) and representative soil constituents in the presence of water. We are about to publish (de Oliveira et al., 2005) a study of carbaryl (1-naphthyl-N-methyl-carbamate) sorption to smectites saturated with six different cations in which FTIR spectra were gathered for every point on each sorption isotherm. Sorption was quite strong for a naphthyl-sized pesticide, roughly 2% by weight for two
different Ca-smectites. The results are very interesting in that the amount of sorption was apparently inversely proportional to the spectroscopic interactions between interlayer cations and the pesticide molecules. That is, even though Mg-smectites sorbed only about 1/3 as much carbaryl as Ba-smectites, for example, the Mg-smectites had a much larger effect on the vibrational spectrum of carbaryl. Thus, it may be inferred that adsorbed carbaryl has to interact with interlayer cations in all smectites, but that such interactions are not the driving force for adsorption. In our previous studies of strong NOC sorption to K-smectites, we demonstrated that K-NOC interactions increased with adsorption and inferred that interlayer K-NOC complex formation was the driving force for adsorption, but this appears to not be the case when Ca-smectites adsorb pesticides strongly.
Impacts
The current project goal is to define the molecular mechanisms of pesticide-clay-water interactions. That is, to determine which pesticide properties and which soil clay properties contribute to the strong sorption of nonionic organic compounds (NOCs) and how those properties interact to cause sorption. The special foci of the current project are Ca- and Al-smectites, which are important in a practical sense because a) Smectite clays are common in agricultural soils and dominate the surface area of many soils, b) We have shown that sorption of many NOCs by smectites dwarfs their sorption by soil organic matter, c) Ca cations dominate the surfaces of smectites in the most agriculturally productive soils of the upper midwest, great plains, and northeast U.S., and d) Al cations dominate the surfaces of smectites in many soils of the southeastern U.S. Thus, if we can make a significant contribution to understanding the mechanisms of pesticide adsorption to Ca- and
Al-smectites, it will have a major impact on our understanding of pesticide adsorption and fate in agricultural soils of the U.S. Mechanistic understanding of adsorption is key to our ability to rationally manage new pesticide applications in a manner that sustains agricultural productivity without impairing environmental quality.
Publications
- Arroyo, L.J., H. Li, B.J. Teppen, C.T. Johnston, and S.A. Boyd. 2004. Hydrolysis of carbaryl by carbonate impurities in reference clay SWy-2. J. Agric. Food Chem. 52:8066-8073.
- Arroyo, L.J., H. Li, B.J. Teppen, and S.A. Boyd. 2005. A simple purification method for reference clays. Clays Clay Miner. 53(5):512-520.
- Chappell, M.A., D.A. Laird, M.L. Thompson, H. Li, B.J. Teppen, V. Aggarwal, C.T. Johnston, and S.A. Boyd. 2005. Influence of smectite hydration and swelling on atrazine sorption behavior. Environ. Sci. Technol. 39:3150-3156.
- de Oliveira, M.F., C.T. Johnston, G.S. Premachandra, B.J. Teppen, H. Li, D.A. Laird, D. Zhu, and S.A. Boyd. 2005. Spectroscopic study of carbaryl sorption on smectite from aqueous suspension. Environ. Sci. Technol. 39 (in press, web release at URL: http://dx.doi.org/10.1021/es048108s).
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