نوع مقاله : مقاله کامل علمی پژوهشی
نویسندگان
1 دانشگاه علوم کشاورزی و منابع طبیعی گرگان
2 دانشجو دکتری علوم خاک گرگان
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Background and Objectives: Environmental pollution caused by the use of pesticides is one of the most important factors that threaten the health of ecosystems and humans, therefore, it is necessary to investigate the fate of herbicides used in the soil to minimize their mobility in the soil and control groundwater pollution.
Clopyralid herbicide is widely used in agricultural products of Gorgan Bay region, and little study has been done in the country regarding the fate of this herbicide in the soil. Due to the concern of high leaching risk of this herbicide in the soil and penetration into the groundwater, this study was conducted with the aim of evaluating the leaching depth and half-life of clopyralid herbicide in the soil and its presence in the groundwater of the region in field conditions.
Materials and Methods: This study was conducted in a part of the farms of Bandargaz city. For this purpose, two canola fields located in the west and east of the area were considered. After using this herbicide at the end of December 2021, was sampled at the times of 1, 14, 28, 56, 86 and 116 days after spraying, from the depths of 0-17, 17-34, 34-51 and 51-67 cm with three repetitions in each field. Also, to check the water pollution status of wells in the region, samples were taken from 4 wells in five periods. To extract the clopyralid residue from soil and water, a high-performance liquid chromatography method was used in the reverse phase, which was equipped with a UV-Vis detector.
Results: The first-order kinetic model predicted well the changes of clopyralid herbicide concentration with time. 56 days after spraying, the amount of deep penetration of this herbicide in the soil of both fields was up to a maximum depth of 34 cm. The results showed that the subsurface soil of the eastern part (sandy loam) was coarser than the western part (loam). The constant values of decomposition rate (k) in the western farm in the surface and subsurface sections were 0.06 and 0.04, respectively, and in the eastern farm in the surface and subsurface sections, respectively, 0.05 and 0.03. The half-life of clopyralid (DT50) was 12 and 18 days in the surface and subsurface parts of the western field, and 13 and 26 days in the surface and subsurface parts of the eastern field, respectively. The value of GUS index was also greater than 2.8 in both farms, which indicates the risk of leaching of this herbicide. The results of clopyralid residue analysis in well water samples indicated the absence of herbicide in them.
Conclusion: In field conditions, herbicide leaching plays an important role in predicting its residues in soil. Also, organic materials accelerate the process of clopyralid decomposition and reduce its half-life. The evaluation of the risk of clopyralid contamination with the Jury model also showed that its application in areas where the amount of soil organic matter is less than one percent, the soil texture is light and the water holding capacity is low should be done with caution.
کلیدواژهها [English]
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