Crop protection pesticide spraying aims to greatly improve the utilization rate of pesticides. Controlling pesticides deposition requires a thorough understanding of the spatial behaviour of spray droplets.The Qinghai-Tibet Plateau, which is the headwaters of three largest water resources (Yangtze, Yellow and Lancang) in China, has exceptionally unique climatic characteristics. The goal is to reduce the amount of pesticides entering water resources. The wind tunnel experiment was used to validate the discrete phase method for tracking the trajectories. Cooperation between the smaller and larger droplets (greater than 150 μm) in the dense area around the nozzle can undoubtedly enhance the initial dispersion of droplet sizes. Droplet coalescence, which lowers the proportion of readily dispersed droplets, can greatly boost droplet deposition onto the target location.The crucial drift height is presented and clarified when droplets gradually disperse by identifying the descending length at which efficiency of mass transit starts towards decrease off quickly. The pesticide transport efficiency will not be enhanced by reducing the initial relative spread of droplets if the actual spray height surpasses the crucial drift height, and may even worsen drift loss. The temperature and relative humidity of the air have a greater influence on the evaporation losses of droplets smaller than 150 μm. In addition to providing information about pesticide spraying, the results of studies on droplet drift behaviors also suggest a method for controlling drift.

The use of pesticides has led to increased soil and water pollution, which has even affected the world's third pole, the Tibetan Plateau. In this study, the adsorption and desorption experiments of spirotetramat on three typical soils were conducted to investigate the migration and leaching risk of pesticides in the Qinghai-Tibet Plateau ecosystem. We used batch equilibrium technique for adsorption-desorption experiments and evaluated leaching risk by computational simulation experiments under laboratory conditions. The Freundlich adsorption constants K_f of spirotetramat in the soils of Haidong, Haixi and Haibei were as follows: At 22.26, 15.13 and 6.85, the maximum adsorption capacity C_max was 434.80, 217.40 and 169.50 mg/kg, the average adsorption rates were 77.92, 54.27 and 39.13%, and the desorption constants (K_f) were 43.27, 22.35 and 11.56, respectively. The hysteresis coefficient HI>1.00 in the soil of Haidong and Haixi, and 0.70<HI<1.00 in the soil of Haibei, indicating that with the increase of temperature, the adsorption capacity of the tested soil for spirotetramat decreases, which increases the migration risk of pesticides. The desorption of spirotetramat in the soil of Haidong and Haixi has a lag. The GUS values of spirotetramat in the soils of Haidong, Haixi and Haibei were 1.15, 1.63 and 1.72, respectively, which were all lower than 1.80, indicating that spirotetramat was a non-leaching pesticide, and the leaching risk of spirotetramat in the soils of Qinghai was small, and the potential harm to groundwater was at a low level.

This study established an HPLC-MS/MS method to quantify the enantiomers of spirotetramat in tubifex. To assess the accuracy and precision of the approach, recovery tests were conducted for insecticide. For all enantiomers, the limits of detection were 0.003 mg/kg. The quantization limits were 0.01 mg/kg. Spirotetramat enantiomers recovery rates in tubifex were found to be between 81 and 114%, with relative standard deviations being less than 7%. The half-lives of spirotetramat enantiomers in tubifex were 3.81–10.58 d, respectively. The 22.4% spirotetramat suspension was sprayed on tubifex three times at a low dosage (high dosage advised). After 14 days after harvesting, the terminal residues of spirotetramat enantiomers in the tubifex were less than 0.03 mg/kg. The findings offer a quantitative foundation for setting China’s maximum residue limits as well as a recommendation for the safe and responsible usage of spirotetramat enantiomers in tubifex.