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United States Department of Agriculture

Agricultural Research Service

Telone (1,3-D)
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Aniline

To understand the potential pathway of chemical degradation of 1,3-D in amended soil, the reaction of 1,3-D with aniline was determined at 25°C in solution. The NH 2group on aniline functions as a nucleophile, and was found to react readily with CH 3Br and CH 3I in a previous study (Gan and Yates, 1996). Water solution containing 5 mM aniline and 0.2 mM 1,3-D was prepared and transferred to 21-mL headspace vials, and the vials were immediately sealed. Disappearance of 1,3-D isomers from the solution was determined by periodically analyzing the ethyl acetate extract by GC-ECD. At the end of reaction, an aliquot of ethyl acetate extract was injected into an HP5890 GC in tandem with an HP5971 MSD to obtain mass spectra of the reaction products. The conditions were: RTX-624 or HP-5MS column (cross-linked 5% phenyl methyl silicone, 30 m × 0.25 mm × 0.25 μm, Hewlett Packard); 0.9 mL min-1 helium flow rate; 80°C initial oven temperature (2 min), ramping at 5°C min-1 to 200°C; 70 eV in EI mode; and 14 to 200 m/z scanning range.
 
Results
The possible involvement of SN 2mechanism was illustrated from the rapid disappearance of 1,3-D isomers in 5 mM aniline solution that was 5 times faster than that in water. As aniline was present in abundance to 1,3-D, the second-order reaction followed a pseudo first-order (r 2= 1.00). Compared to MeBr degradation under the same conditions (k = 0.24 d -1), disappearance of 1,3-D isomers (k = 0.55-0.59 d -1) was about 2.3 times as fast (Gan and Yates, 1996). GC/MS analysis of the ethyl acetate extract showed two peaks after aniline: peak 1 had a retention time of 25.7 min on the RTX-624 column and 16.4 min on the HP-5MS column, and peak 2 had respective retention times of 26.6 and 17.0 min. Both peaks on either column gave identical spectra, indicating that they were likely isomers to each other. From the spectrum, it was tentatively determined that the reaction products were isomers of 3-chloroallyl aniline (MW = 167), the product of SN 2substitution at the N position of aniline by chloride on C3 of the 1,3-dichloropropene molecule.
 

Reaction with Composted Manure
 
Effect of Amendment Rates on the Degree of Acceleration
The potential use of soil organic matter amendments for reducing 1,3-D emissions on a management scale must consider amendment rates that are practical for field applications. To determine the dependence of enhanced degradation on amendment rates, 1,3-D degradation was measured in soils amended with different proportions of CM. Degradation of both 1,3-D isomers in nonsterilized amendment-soil mixes was essentially unaffected when the mixing ratio was reduced from 1:2 to 1:8. It then decreased, but not proportionally, as the ratio further decreased from 1:8 to 1:40 (Table 2).
 
The non-proportionality of the response of degradation to the mixing ratio was reflected in that, at 1:40, the degradation of the (E) or (Z) isomer was still about 3 times as fast as that in the unamended soil (Table 2). The rapid degradation of 1,3-D at such a low amendment-to-soil ratio implies that significantly enhanced degradation can be achieved with typical field application rates of amendments (10-50 t ha-1). Disappearance of 1,3-D at various mixing ratios generally followed first-order kinetics, with better fits in the 1:2 to 1:8 range than at the lower ratios, and in the sterilized mixes as compared to the nonsterilized mixes (Table 2). When the disappearance of 1,3-D in the nonsterilized mixes was depicted on a logarithmic scale, it becomes apparent that two phases began to develop as the mixing ratio was decreased from 1:8 to 1:40; and the degradation during the second phase was consistently more rapid than during the first phase (Fig. 4). The initialization of the second phase was prolonged as the ratio decreased, and the biphasic phenomenon was more evident for (E) 1,3-D than that for (Z) 1,3-D (Fig. 4). It is likely that at high CM rates, stimulated biodegradation occurred immediately after the treatment, and the first phase was too short to be visible. Microbial activity measured as CO2 evolution showed a similar response to the mixing ratio as did the 1,3-D degradation (Table 1). For instance, the total amount of CO2 evolved from 50 g of the 1:40 mix during the 6-d incubation was 5.8 mg, which was almost 70% of that from the 1:2 mix, or 12 times that from the unamended soil. The contribution of biodegradation to the overall 1,3-D degradation as induced by amendment addition was calculated for various mixing ratios from the difference of degradation rate constant k (d-1) between the sterilized and nonsterilized treatments (Table 2). For (Z) 1,3-D, biodegradation contributed about 60-70% of the induced degradation for mixing ratios ranging from 1:2 to 1:8, but this figure increased to about 80% when the mixing ratio was decreased to 1:20 or 1:40 (Table 2). Similar trends were also found among the different mixes for (E) 1,3-D (Table 2). Therefore, it can be concluded that while chemical degradation was significant (30-40% of the enhanced degradation) for soils amended with CM at high rates, its role gradually decreased and microbial degradation gained more dominance as the amendment-to-soil ratio was further reduced.
 
Reduction of 1,3-D Emissions by Surface Amendment
Volatilization losses of 1,3-D from unamended and CM-amended soil columns were followed for 432 h (or 18 d) after Telone-II was injected at the 30 cm depth. The averaged volatilization fluxes in μg h-1 and the cumulative losses in % of applied fumigant are given for both isomers in Fig. 5. The volatilization fluxes of (Z) or (E) 1,3-D during the first 200 h were much greater from the unamended columns than columns containing 1:20 CM-amended soil in the top 5 cm, though the difference gradually diminished thereafter (Fig. 5a). For instance, the maximum flux for (Z) 1,3-D from the unamended treatment was >2.5 times that from the amended treatment. Cumulatively, about 34% and 25% of the applied (Z) and (E) 1,3-D were lost, respectively, from the unamended columns at the end of the experiment. In comparison, the total loss of (Z)- and (E) 1,3-D from the CM-amended columns was only 18% and 14% of the applied amount, a reduction of >40% of that from the unamended soil (Fig. 5b). As column packing, fumigant treatment, sampling and sample analysis were kept under the same conditions for all four columns, the difference in 1,3-D emissions between the two treatments can be mainly attributed to the incorporation of 5% CM into the top 5-cm soil layer. The results from this experiment are therefore indicative of the potential usefulness of surface amendment as a management practice for minimizing 1,3-D emissions. More studies, such as emission monitoring and efficacy tests under field conditions, however, should be conducted to validate these laboratory observations. Longevity of soil organic matter amendments for causing enhanced degradation, and interactions of amendments and fumigant leaching should be also investigated.
 
Summary
This research demonstrates that integrating organic amendments with 1,3-D fumigation may significantly reduce 1,3-D atmospheric emissions by causing enhanced rates of fumigant degradation. Rapid degradation occurred at amendment rates low enough to allow realistic applications under field conditions, where the amended surface layer may act as a "cap" to reduce the emission, but the concentration below is not lowered to compromise the efficacy. This approach can be especially beneficial for sandy textured soils, where gas-phase diffusion is very rapid and degradation is relatively slow. As the negative environmental and toxicological effects of chemical fumigants are being realized, but applicable non-chemical methods are yet to be developed, environment-benign and yet effective strategies that integrate multiple approaches are urgently needed for soilborne pest control. The findings from this study indicate a promising integration of 1,3-D fumigation and organic amendment application that warrant further research on larger scales and under different conditions.
 
Volatilization of 1,3-dichloropropene isomers
 
Volatilization of 1,3-dichloropropene isomers from columns packed with the Arlington sandy loam with and without composted manure amendment after Telone-II was injected at the 30 cm depth. Voaltilization fluxes in μg/h

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Cumulative volatilization losses
Cumulative volatilization losses in % of applied 1,3-D

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References
 
Gan, J., Yates, S.R., Spencer, W.F. and Yates, M.V. Automated headspace analysis of fumigants 1,3-dichloropropene and methyl isothiocyanate on charcoal sampling tubes, Journal Chromatography A. 684:121-131. 1994.

Gan, J., Yates, S.R., Crowley D. and Becker, O.J. Acceleration of 1,3-D degradation by organic amendments and potential application for emission reduction. Journal Environmental Quality. 27: 408-414. 1998.

Gan, J., Yates, S.R., Wang, D. and Ernst F.F. Effect of application methods on 1,3-Dichloropropene volatilization from soil under controlled conditions. Journal Environmental Quality. 27: 432-438. 1998.

Wang, D., and Yates, S.R. Spatial and temporal distributions of 1,3-dichloropropene in soil under drip and shank application and implications for pest control efficacy using concentration time index. Pesticide Science. 55:154-160. 1999.

Wang, D., Yates, S.R., Gan, J., and Knuteson, J.A. Atmospheric volatilization of methyl bromide, 1,3-dichloropropene, and propargyl bromide through two plastic films, transfer coefficient and temperature effect, Atmospheric Environment. 33:401-407. 1999.

Gan, J., Yates, S.R., Becker, J.O. and Knuteson, J. Transformation of 1,3-dichloropropene by thiosulfate fertilizers. Journal of Environmental Quality 29:1476-1481. 2000.

Wang, D., Knuteson, J. and Yates, S.R. Two-Dimensional model simulation of 1,3-D volatilization and transport in a field soil. Journal Environmental Quality 29:639-644. 2000.

Dungan, R., Gan, J. and Yates, S.R. Effect of temperature, organic amendment rate, and moisture content on the degradation of 1,3-dichloropropene in soil. Pesticide Management Science 57:1107-1113. 2001.

Ibekwe, A.K, Papiernik, S.K., Gan, J., Yates, S.R., Crowley D. and Yang, C.-H. Microcosm enrichment of 1,3-dichloropropene-degrading soil microbial communities in a compost-amended soil. J. Applied Microbiology 91:668-676. 2001.

Wang, D., Yates, S.R., Ernst, F.F. and Knuteson, J. Volatilization of 1,3-dichloropropene under different applications methods. Water, Air and Soil Pollution 127:109-123. 2001.

Wang, Q., Gan, J., Papiernik, S.K. and Yates, S.R. Isomeric Effects of Thiosulfate Transformation and Detoxification of 1,3-Dichloropropene. Environmental Toxicology and Chemistry 20:960-964. 2001.

Kim, J., Farmer, W., Gan, J., Yates, S.R, Papiernik, S.K. and Dungan, R.S. Organic matter effects on phase partition of 1,3-dichloropropene in soil, Journal of Agricultural and Food Chemistry. 2003. (accepted 11/6/2002)

Guo, M., Papiernik, S.K., Zheng, W. and Yates, S.R. Effect of environmental factors on 1,3-dichloropropene hydrolysis in water and soil. Journal Environmental Quality. 2003. (in press)

Zheng, W., Papiernik, S.K., Guo, M. and Yates, S.R. Competitive degradation between fumigants chloropicrin and 1,3-dichloropropene in unamended and amended soils, Journal Environmental Quality (in press)

Xu, J., Gan, J., Papiernik, S.K, Becker, J.O., and Yates, S.R. Interactions of methyl bromide and 1,3-D with soil organic matter. 2003. (in press)
 

Last Modified: 11/4/2009