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The aim of the studies was to determine the influence of soil type (texture and organic carbon content) on metazachlor decay in soil. The experiment was carried out in laboratory conditions (plant growth chamber). Metazachlor was applied to three different soils (contrasting textures and organic carbon content). Soil samples were taken for analyses 1 hour (initial concentration) and 2, 4, 8, 16, 32, 64 and 96 days after treatment. Metazachlor residue was analysed using GC/ECD (gas chromatography with electron capture detector). Good linearity was found between logarithmic concentration of metazachlor residues and time. The differences in texture (content of sand, silt and clay) and the organic carbon content influenced on metazachlor decay in soil. Values of DT50 obtained in the experiment varied from 22 to 35 days. A high concentration of clay fraction in soil texture and high organic carbon content increased of metazachlor degradation (the DT50 value was the smallest).
The aim of investigation was to elaborate an analytical method for determination of bentazone in soil, plant and water samples. The analytical procedure consists of three elementary processes: extraction and reextraction of analyzed substance from matrix, cleaning of extract using SPE (Solid Phase Extraction) column with Florisil active solid and final determination using gas chromatography with ECD and MS detection. The detection limit (LOD) of bentazone was 0.0002 mg/kg (for soil and plant samples) and 0.00005 mg/kg for water samples. The range of fortified recoveries of the method was 92–98%.
The aim of present investigation was to evaluate the influence of lowrates application on herbicide residues in soil and roots of sugar beet. Chemical weed control in sugar beet was applied at recommended and reduced (about 50 and 66%) doses of herbicides including substances such as: phenmedipham, desmedipham, ethofumesate, metamitron, triflusulfuron and oil adjuvant applied 4 times at 7- to 10-day intervals starting at the onset of weed emergence. Samples of soil and roots of sugar beet were taken at the day of lifting. Phenmedipham, desmedipham and ethofumesate residues were analysed using HPLC with UV-detection. Metamitron residues were analysed using GLC with ECD detection. At lifting time, in soil samples, where recommended herbicide doses were applied, the residues of separate active substance of herbicides amounted from 0.0056 to 0.0124 mg.kg-1. Sum of all detected residues of applied substances amounted 0.0323-0.0373 mg.kg-1. In sugar beet root samples, the residues amounted respectively 0.0011 to 0.0085 mg.kg-1and 0.0085-0.0224 mg.kg-1. Application of the reduced doses by about 50% influenced on a significant decrease of residues about 38-50% average. For samples, where reduction of herbicide dose amounted 66%, the decrease of residues level, in comparison with results obtained at recommended doses, was statistically significant and amounted 69-77% average. Residues of active substances determined in roots of sugar beet did not exceed EU acceptable limits.
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