Department of Pesticide Chemistry and Technology, Faculty of Agriculture, Alexandria University, Aflaton St., El-Shatby, Alexandria, 21545, Egypt.
Land and Water Technologies Department, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications (SRTA-City), New Borg El-Arab, Alexandria, 21934, Egypt.
Sci Rep. 2024 Mar 8;14(1):5717. doi: 10.1038/s41598-024-56083-5.
To determine the extent of pesticide buildup and their environmental contamination, the environmental half-lives of pesticides are examined. The influence of the factors affecting the half-lives of fipronil and thiamethoxam including soil type, sterilization, temperature, and time and their interactions was studied using experimental modeling design by Minitab software. Based on the dissipation kinetics data, fipronil concentrations reduced gradually over 60 days while thiamethoxam concentrations decreased strongly. Also, fipronil and thiamethoxam dissipated more rapidly in calcareous soil than in alluvial soil. Thiamethoxam, however, disappeared more rapidly than fipronil in all treatments. Incubation at 50 °C leads to rapid the pesticide degradation. For prediction of the dissipation rate, model 5 was found to be the best fit, Residue of insecticide (%) = 15.466 - 11.793 Pesticide - 1.579 Soil type + 0.566 Sterilization - 3.120 Temperature, R = 0.94 and s = 3.80. Also, the predicted DT values were calculated by a model, DT (day) = 20.20 - 0.30 Pesticide - 7.97 Soil Type + 0.07 Sterilization - 2.04 Temperature. The shortest experimental and predicted DT values were obtained from treatment of thiamethoxam at 50 °C in calcareous soil either sterilized (7.36 and 9.96 days) or non-sterilized (5.92 and 9.82 days), respectively. The experimental DT values of fipronil and thiamethoxam ranged from 5.92 to 59.95 days while, the modeled values ranged from 9.82 to 30.58 days. According to the contour plot and response surface plot, temperature and sterilization were the main factors affecting the half-lives of fipronil and thiamethoxam. The DT values of fipronil and thiamethoxam increased in alluvial soil and soil with low temperature. In general, there is a high agreement between the experimental results and the modeled results.
为了确定农药积累的程度及其对环境的污染，需要检测农药的环境半衰期。本研究采用 Minitab 软件的实验模型设计，研究了土壤类型、灭菌、温度、时间以及它们之间的相互作用对氟虫腈和噻虫嗪半衰期的影响。基于消解动力学数据，氟虫腈在 60 天内逐渐减少，而噻虫嗪浓度则急剧下降。此外，氟虫腈和噻虫嗪在石灰性土壤中的消解速度快于冲积土。然而，在所有处理中，噻虫嗪的消解速度快于氟虫腈。在 50°C 下培养会导致农药快速降解。对于预测消解速率，发现模型 5 拟合度最高，残留杀虫剂（%）=15.466-11.793 杀虫剂-1.579 土壤类型+0.566 灭菌-3.120 温度，R=0.94，s=3.80。此外，还通过模型计算了预测的 DT 值，DT（天）=20.20-0.30 杀虫剂-7.97 土壤类型+0.07 灭菌-2.04 温度。在石灰性土壤中，噻虫嗪在 50°C 下无论是灭菌（7.36 和 9.96 天）还是未灭菌（5.92 和 9.82 天）处理，其实验和预测的 DT 值都最短。氟虫腈和噻虫嗪的实验 DT 值范围为 5.92-59.95 天，而模型值范围为 9.82-30.58 天。根据等高线图和响应面图，温度和灭菌是影响氟虫腈和噻虫嗪半衰期的主要因素。在冲积土和低温土壤中，氟虫腈和噻虫嗪的 DT 值增加。总的来说，实验结果与模型结果吻合较好。
