Progress 10/15/01 to 10/14/05
Outputs
Termination Report: We have completed this project after receiving one year no-cost extension from USDA-CSREES. Chloroacetanilide herbicides, including alachlor, metolachlor, propachlor, and acetochlor, are among the most heavily used herbicides in the United States. The combined annual use of these herbicides has remained at >100 million lbs each year in the United States. This use pattern clearly suggests that chloroacetanilide herbicides are vitally important for the productivity of U.S. agriculture. However, because of their widespread use, these herbicides are a ubiquitous source of contamination of soil and water resources. We discovered a novel reaction, in which chloroacetanilide herbicides are dechlorinated by thiosulfate, yielding initial products of little biological activity. Because common thiosulfate salts are fertilizers or otherwise inexpensive products, this finding has great promise for practical implementation in many contaminant management
scenarios. We proposed to investigate the feasibility and conditions of using thiosulfate salts to decontaminate acetanilide herbicide residues from soil, water and aquifers, and to identify other susceptible contaminants or other nucleophiles.We have completed experiments to understand the kinetics of herbicide-thiosulfate reaction and to determine the fate of the initial reaction products. We further discovered that even more rapid dechlorination reaction occurs between chloroacetanilide herbicides and polysulfides, and the rate of reaction was about two orders of magnitude faster than that for thiosulfate under comparable conditions. We have completed experiments in aqueous phase to understand the kinetics of this reaction, and soil incubation experiments to evaluate the reaction kinetics in soil. The results show that polysulfides greatly enhanced the dissipation of these herbicides in soil, and the degree of enhancement was affected by the pesticide adsorption to the solid phase.
We have also completed column leaching experiments to test the use of approach for removing pesticide residues present in soil. We are in the process of compiling data and preparing manuscripts for publication.
Impacts
Impact: Using thiosulfate salts to detoxify chloroacetanilide herbicides is a novel approach for environmental decontamination. There can be many scenarios to use this reaction. For example, this approach can be used for decontaminating spill sites, disposing wastes or waste water, and cleaning containers or equipment. The characteristics of this reaction also imply that many other halogenated environmental contaminants may be susceptible to this reaction. Our further finding that even faster reaction can occur with polysulfides suggests that using strong nucleophiles to dehalogenated certain organic contaminants may have general significance. Therefore, this line of research may lead to the development of inexpensive and safe remediation methods of general application.
Publications
- Gan, J., Q. Wang, S.R. Yates, W.C. Koskinen, and W.A. Jury. 2002. Dechlorination of chloroacetanilide herbicides by thiosulfate salts. Proceedings of National Academy of Sciences (USA) 99: 5189-5194. Gan, J., P.C. Zhu, S.D. Aust, and A.T. Lemley. 2003. Pesticide Decontamination and Detoxification. ACS Symposium Series 863. ACS, Washington, DC. 266 p.
- Gan, J., and S. Bondarenko. 2003. Detoxification of some halogenated pesticides by thiosulfate salts. In Gan J. et al. (Eds) Pesticide Decontamination and Detoxification. ACS Symposium Series 863. ACS, Washington, DC. pp. 51-65.
- Bondarenko, S., and J. Gan. 2005. Dehalogenation of halogenated fumigants by polysulfide salts. Journal of Agricultural & Food Chemistry (submitted
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Progress 01/01/04 to 12/31/04
Outputs
We have requested and received one year no-cost extension on this project. Chloroacetanilide herbicides, including alachlor, metolachlor, propachlor, and acetochlor, are among the most heavily used herbicides in the United States. The combined annual use of these herbicides has remained at >100 million lbs each year in the United States. This use pattern clearly suggests that chloroacetanilide herbicides are vitally important for the productivity of U.S. agriculture. Because of their widespread use, these herbicides are a ubiquitous source of contamination of soil and water resources. We discovered a novel reaction, in which chloroacetanilide herbicides are dechlorinated by thiosulfate, yielding initial products of little biological activity. Because common thiosulfate salts are fertilizers or otherwise inexpensive products, this finding has great promise for practical implementation in many contaminant management scenarios. We proposed to investigate the feasibility
and conditions of using thiosulfate salts to decontaminate acetanilide herbicide residues from soil, water and aquifers, and to identify other susceptible contaminants or other nucleophiles. We have completed experiments to understand the kinetics of herbicide-thiosulfate reaction and to determine the fate of the initial reaction products. We further discovered that even more rapid dechlorination reaction occurs between chloroacetanilide herbicides and polysulfides, and the rate of reaction was about two orders of magnitude faster that for thiosulfate under comparable conditions. We have completed experiments in aqueous phase to understand the kinetics of this reaction, and incubation experiments to evaluate the reaction kinetics in soil. The results show that polysulfides greatly enhanced the dissipation of these herbicides in soil, and the degree of enhancement was affected by the pesticide's adsorption to the solid phase. We are currently conducting column leaching experiments to
test the use of approach for removing pesticide residues present in soil. These experiments will provide information on the feasibility of use on remediation of contaminated soil sites.
Impacts
Using thiosulfate salts to detoxify chloroacetanilide herbicides is a novel approach for environmental decontamination. There can be many scenarios to use this reaction. For example, this approach can be used for decontaminating spill sites, disposing wastes or waste water, and cleaning containers or equipment. The characteristics of this reaction also imply that many other halogenated environmental contaminants may be susceptible to this reaction. Our further finding that even faster reaction can occur with polysulfides suggests that using strong nucleophiles to dehalogenated certain organic contaminants may have general significance. Therefore, this line of research may lead to the development of inexpensive and safe remediation methods of general application.
Publications
- Yang, W.C., J. Gan, S. Bondarenko, and W.P. Liu. 2004. Nucleophilic radical substitution reaction of triazine herbicides with polysulfides. Journal of Agricultural & Food Chemistry 54, 7051-7055.
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Progress 01/01/03 to 12/31/03
Outputs
Chloroacetanilide herbicides, including alachlor, metolachlor, propachlor, and acetochlor, are among the most heavily used herbicides in the United States. The combined annual use of these herbicides has remained at >100 million lbs each year in the United States. This use pattern clearly suggests that chloroacetanilide herbicides are vitally important for the productivity of U.S. agriculture. Because of their widespread use, these herbicides are a ubiquitous source of contamination of soil and water resources. We discovered a novel reaction, in which chloroacetanilide herbicides are dechlorinated by thiosulfate, yielding initial products of little biological activity. Because common thiosulfate salts are fertilizers or otherwise inexpensive products, this finding has great promise for practical implementation in many contaminant management scenarios. We proposed to investigate the feasibility and conditions of using thiosulfate salts to decontaminate acetanilide
herbicide residues from soil, water and aquifers, and to identify other susceptible contaminants or other nucleophiles. We have completed experiments to understand the kinetics of herbicide-thiosulfate reaction and to determine the fate of the initial reaction products. The reaction rate between alachlor, acetochlor, propachlor, and metolachlor with thiosulfate was measured as a function of the initial thiosulfate concentration. To understand the fate of the reaction products, in a separate study, 14C-labelled metolachlor was reacted with thiosulfate and then used to treat soil samples. The treated soils were incubated at the ambient temperature, and evolution of 14CO2 was collected and monitored. This analysis will show the mineralization of thiosulfate-metolachlor product in soil, and formation of intermediates. We further discovered that very fast reaction also occurs between chloroacetanilide herbicides and polysulfides, and the rate of reaction was about two orders of magnitude
faster that for thiosulfate. We have completed experiments in aqueous phase to understand the kinetics of this reaction, and will further design experiments to evaluate the reaction in soil. We anticipate that there could be wide applications of this reaction for pollution prevention and remediation of point source contamination.
Impacts
Using thiosulfate salts to detoxify chloroacetanilide herbicides is a novel approach for environmental decontamination. There can be many scenarios to use this reaction. For example, this approach can be used for decontaminating spill sites, disposing wastes or waste water, and cleaning containers or equipment. The characteristics of this reaction also imply that many other halogenated environmental contaminants may be susceptible to this reaction. Our further finding that even faster reaction can occur with polysulfides suggests that using strong nucleophiles to dehalogenated certain organic contaminants may have general significance. Therefore, this line of research may lead to the development of inexpensive and safe remediation methods of general application.
Publications
- Gan, J., Q. Wang, S.R. Yates, W.C. Koskinen, and W.A. Jury. Dechlorination of chloroacetanilide herbicides by thiosulfate salts. Proceedings of National Academy of Sciences (USA) 99: 5189-5194, 2002. Gan, J., P.C. Zhu, S.D. Aust, and A.T. Lemley. 2003. Pesticide Decontamination and Detoxification. ACS Symposium Series 863. ACS, Washington, DC. 266 p.
- Gan, J., and S. Bondarenko. 2003. Detoxification of some halogenated pesticides by thiosulfate salts. In Gan J. et al. (Eds) Pesticide Decontamination and Detoxification. ACS Symposium Series 863. ACS, Washington, DC. pp. 51-65.
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Progress 01/01/02 to 12/31/02
Outputs
Chloroacetanilide herbicides, including alachlor, metolachlor, propachlor, and acetochlor, are among the most heavily used herbicides in the United States. The combined annual use of these herbicides has remained at greater than100 million lbs each year in the United States. This use pattern clearly suggests that chloroacetanilide herbicides are vitally important for the productivity of U.S. agriculture. Because of their widespread use, these herbicides are a ubiquitous source of contamination of soil and water resources. We discovered a novel reaction, in which chloroacetanilide herbicides are dechlorinated by thiosulfate, yielding initial products of little biological activity. Because common thiosulfate salts are fertilizers or otherwise inexpensive products, this finding has great promise for practical implementation in many contaminant management scenarios. We started to evaluate the feasibility and conditions of using thiosulfate salts to decontaminate
acetanilide herbicide residues from soil, water and aquifers, and to identify other susceptible contaminants or other even stronger nucleophiles. We have carried out studies to understand the kinetics of herbicide-thiosulfate reaction and to determine the fate of the initial reaction products. The reaction rate between alachlor, acetochlor, propachlor, and metolachlor with thiosulfate was measured as a function of the initial thiosulfate concentration and temperature. Information on temperature independence is critical for understanding the mechanism of this reaction. In another experiment, carbon 14-labelled metolachlor was reacted with thiosulfate and then used to treat soil samples. The treated soils were incubated at the ambient temperature, and evolution of carbon 14 of carbon dioxide was collected. This analysis will show the mineralization of thiosulfate-metolachlor product in soil, and formation of intermediates. In our recent study, we discovered that very fast reaction also
occurs between chloroacetanilide herbicides and polysulfides, and the rate of reaction was two orders of magnitude as rapid as with thiosulfate under comparable conditions. We are currently conducting kinetics experiments to quantitatively describe this reaction, and to understand the mechanisms of this reaction. We further found that the reaction with polysulfides also happen with a number of chlorinated hydrocarbons that are typically resistant to chemical or microbial transformations in the environment. We anticipate that there could be wide applications of this reaction for pollution prevention and remediation of point source contamination.
Impacts
Using thiosulfate salts to detoxify chloroacetanilide herbicides is a novel approach for environmental decontamination. There can be many scenarios to exploit this reaction. For example, this approach can be used for decontaminating spill sites, disposing wastes or waste water, and cleaning containers or equipment. The characteristics of this reaction also imply that many other halogenated environmental contaminants may be susceptible to this reaction. Our further finding that even faster reaction can occur with polysulfides suggests that using strong nucleophiles to dehalogenated certain organic contaminants may have s=general significance. Therefore, this line of research may lead to the development of inexpensive and safe remediation methods of general application.
Publications
- Gan, J., Q. Wang, S.R. Yates, W.C. Koskinen, and W.A. Jury. Dechlorination of chloroacetanilide herbicides by thiosulfate salts. Proceedings of National Academy of Sciences (USA) 99: 5189-5194, 2002
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Progress 01/01/01 to 12/31/01
Outputs
Chloroacetanilide herbicides, including alachlor, metolachlor, propachlor, and acetochlor, are among the most heavily used herbicides in the United States. The combined annual use of these herbicides has remained at greater than 100 million lbs each year in the United States. This use pattern clearly suggests that chloroacetanilide herbicides are vitally important for the productivity of U.S. agriculture. Because of their widespread use, these herbicides are a ubiquitous source of contamination of soil and water resources. We discovered a novel reaction, in which chloroacetanilide herbicides are dechlorinated by thiosulfate, yielding initial products of little biological activity. Because common thiosulfate salts are fertilizers or otherwise inexpensive products, this finding has great promise for practical implementation in many contaminant management scenarios. In this project, we will evaluate the feasibility and conditions of using thiosulfate salts to
decontaminate acetanilide herbicide residues from soil, water and aquifers. We are currently carrying out experiments to understand the kinetics of herbicide-thiosulfate reaction and to determine the fate of the initial reaction products. In one on-going experiment, reaction rates between alachlor, acetochlor, propachlor, and metolachlor with thiosulfate are measured as a function of temperature. Information on temperature independence is critical for understanding the mechanism of this reaction. In another on-going experiment, 14C-labelled metolachlor was reacted with thiosulfate and then used to treat soil samples. The treated soils are being incubated at the ambient temperature, and evolution of 14CO2 is collected. This analysis will show the mineralization of thiosulfate-metolachlor product in soil, and formation of intermediates. Studies on reaction between these herbicides with glutathione and thiosulfate with other halogenated compounds are being planned for this year.
Impacts
Using thiosulfate salts to detoxify chloroacetanilide herbicides is a novel approach for environmental decontamination. There can be many scenarios to exploit this reaction. For example, this approach can be used for decontaminating spill sites, disposing wastes or waste water, and cleaning containers or equipment. The characteristics of this reaction also imply that many other halogenated environmental contaminants may be susceptible to this reaction. Therefore, this line of research may lead to the development of an inexpensive and safe remediation method of general application.
Publications
- Gan, Q. Wang, S.R. Yates, W.C. Koskinen, and W.A. Jury. 2002. Dechlorination of chloroacetanilide herbicides by thiosulfate salts. Submitted to Proc. National Academy of Science (USA).
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