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20232
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Subject: Chemistry × End date: 2023 × Start date: 2023 × Type: Thesis × Thesis Type: Ph.D ×
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    ThesisItemOpen Access
    Persistence, mitigation and leaching of atrazine and its metabolites in soil
    (CCSHAU, Hisar, 2023-01) Priyanka; Duhan, Anil
    Persistence, mitigation and leaching potential of atrazine and its metabolites in sandy and clay loam soils was studied. Soil samples were collected periodically for dissipation and mitigation studies. Leaching experiment was performed at 50 μg (single dose) and 100 μg (double dose) in both soils taken in plexi glass columns. Enzymatic activities were studied as per the explained method in available literature. Sample preparation techniques i.e. Matrix solid phase dispersion (MSPD), was optimized using different solvents for both soils at fortification level of 0.001 μg/g for sample preparation. The limits of detection and quantification were ranged 0.0005-0.001 and 0.001-0.005μg/g, respectively for AT and metabolites. In clay loam and sandy loam soil, average recoveries of atrazine and metabolites ranged from 81.3-83.1% and 84.2-86.3%, respectively in methanol. Dissipation followed first-order kinetics. The residues reached below detectable limit after 30 and 60 days in sandy loam and clay loam soils, respectively. Presence of organic manures stimulated while BGC inhibited the dissipation of atrazine in both soils. Urease activity decreased up to 30 days and boosted thereafter up to 60 days in all treatments of clay loam soil. AT exhibited deleterious effect on urease activity up to 30 DAT followed by DEA and DIA in clay loam soil. AT and DEA stimulated while DIA inhibited DHG activity on 0 DAT in comparison to control. The residues of atrazine and its metabolites found in leachate fractions suggested about its highly mobile nature, and possible threat of surface and ground water contamination. The presence of a notable collection of residues in leachate fractions suggests the potential for surface and groundwater contamination. DEA and DIA metabolites, in particular, caused springtail Folsomia candida and earthworm Eisenia fetida to have longer and more unacceptable risks. If residues similar to those found in leachate fractions reach water bodies, they may be toxic to a variety of freshwater fish, aquatic arthropods, amphibians, and aquatic invertebrates. Future research should take a more comprehensive approach to assessing ecological health and potential threats to non-target species.
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    ThesisItemOpen Access
    Persistance and decontamination studies of a combination formulation (pyriproxyfen 5% EC + fenpropathrin 15% EC) in okra and soil
    (CCSHAU, Hisar, 2023-02) Pooja; Sushil
    This study developed and validated a methodology for extracting the residues utilizing the QuChERS method, as well as the conformation and quantification of Pyriproxyfen and Fenpropathrin residues using GC-MS/MS working at low LOQ (0.01 mg kg-1). The field application of recommended (37.5 + 112.5 g a.i. ha-1) and double recommended dose (70 + 225 g a.i. ha-1) leads to initial deposits of Pyriproxyfen (0.359, 0.584 mg/kg) and Fenpropathrin (0.643, 0.951 mg /kg) which dissipated by following first order kinetics with half-life value ranged in between 1.79-1.84 (Pyriproxyfen) and 2.27-2.31 days (Fenpropathrin) at T1-T2 doses, respectively. The estimated pre-harvest intervals (PHI) for Pyriproxyfen and Fenpropathrin were 6.03 and 11.51, 0.91 and 2.54 days at T1 and T2 doses, respectively. There were no residues of Pyriproxyfen and Fenpropathrin in the soil after 1 day of the application of sumiprempt formulation indicating its safety for the next crop. Even though all the decontamination processes were successful in reducing the levels of both chemicals left behind, washing + boiling proved to be the most efficient. Residues of Pyriproxyfen and Fenpropathrin persisted for a little longer period in soil under laboratory conditions. ZIF-8 was synthesized by hydrothermal, sonochemical, and microwave-assisted methods, and its structural, physical, and chemical characteristics were investigated using FTIR, XRD, SEM, BET, and zeta seizer. ZIF-8 achieved a 69%, and 65 % removal of Pyriproxyfen and Fenpropathrin (20 mg/L) under optimized conditions, respectively.