Abstract
The study concerned dissipation of metazachlor and clomazone, herbicides widely used in rapeseed (Brassica napus L. subsp. napus) protection, applied to the clay soil under field and laboratory conditions. Furthermore, the uptake of these pesticide from soil by rapeseed plants was investigated under field conditions. An additional aim of this work was to modify the QuEChERS method for the determination of metazachlor and clomazone in the plant material. Analytical procedures for metazachlor and clomazone qualification and quantification in rapeseed plants and soil were developed, using gas chromatography with an micro electron capture detector (GC-μECD) and a mass detector (GC-MS/MS QqQ) as confirmation. Dissipation kinetics of herbicide residues in soil were described as first-order equations. The analytical performance was very satisfactory and confirmed that the methods meet the requirements of the European Commission. In the conducted field experiments it was found that dissipation of clomazone and metazachlor in clay soil follows first-order kinetics (R2 between 0.964 and 0.978), and half-lives were 9.5 days and 10.2 days for clomazone and metazachlor, respectively. Under laboratory conditions, dissipation of clomazone and metazachlor in soil also follows first-order kinetics (R2 between 0.937 and 0.938), and half-lives were 8.8 days and 5.7 days for clomazone and metazachlor, respectively. Residues of both herbicides in rape plants 22 days after application of herbicides were below the maximum residue levels for Brassica plants. Metazachlor and clomazone dissipate very fast in clay soil and their uptake by rape plants is very low.
Highlights
The study concerned dissipation of metazachlor and clomazone, herbicides widely used in rapeseed (Brassica napus L. subsp. napus) protection, applied to the clay soil under field and laboratory conditions
Codex Alimentarius[5] or The Environmental Protection Agency[6] establish maximum residue levels (MRLs) for pesticides in food, while in the European Union levels of pesticides are controlled in accordance with Regulation 396/20057 and Regulation 149/20088
Soil may be exposed to both industrial and agricultural pollutions, including pesticides. These substances can be introduced into the soil in various ways, e.g. by direct application, accidental spillage, runoff from plants or by the inclusion of plant materials contaminated with pesticides
Summary
The study concerned dissipation of metazachlor and clomazone, herbicides widely used in rapeseed (Brassica napus L. subsp. napus) protection, applied to the clay soil under field and laboratory conditions. Dissipation of clomazone and metazachlor in soil follows first-order kinetics (R2 between 0.937 and 0.938), and half-lives were 8.8 days and 5.7 days for clomazone and metazachlor, respectively Residues of both herbicides in rape plants 22 days after application of herbicides were below the maximum residue levels for Brassica plants. The constantly growing demand for food requires the use of modern methods and technologies in agricultural production, including the use of plant protection products As it is widely known, there is some evidence of advantageous effects of pesticides, such as an increase in the quantity and quality of crops[1], but, at the same time, the intensification of agriculture, including the use of these inherently toxic and highly persistent substances, can lead to environmental contamination, as well as consumer exposure that may be harmful to their health[2,3,4]. The QuEChERS procedure[26] is one of the most commonly used analytical methods for the determination of pesticides residues, and frequently this procedure is modified in terms of amounts and types of reagents, as well as available equipment[27,28,29,30]
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