Department of Chemistry and Biochemistry, Utah State University, Logan, Utah 84322, United States.
Environ Sci Technol. 2022 Sep 20;56(18):13058-13065. doi: 10.1021/acs.est.2c02892. Epub 2022 Sep 6.
Leaf-air partition coefficient () values are needed to understand and predict pesticide volatilization and persistence in agroecosystems. The objectives of this work were to measure values and foliar penetration for the insecticide chlorpyrifos (as an active ingredient alone and in a pesticide formulation) on alfalfa (lucerne) leaves at a range of temperatures and relative humidities and when using leaves collected in different summer months. values were measured using a solid-phase fugacity meter. A portion of the leaves were also used for foliar penetration experiments. values for chlorpyrifos as an active ingredient alone decreased with temperature, while the effects of temperature on chlorpyrifos in the formulation were negligible. No correlations between values and relative humidity were observed. Foliar penetration increased with temperature for chlorpyrifos both as an active ingredient and in the formulation. Increasing foliar penetration with temperature is attributed to increasing diffusion into inner leaf layers. Both volatilization and foliar penetration affect the measured values, so understanding the link between these processes is necessary to predict values. The leaf collection date had a substantial effect on the measured values, highlighting the need for a better understanding of the role of leaf properties on .
叶气分配系数（）值对于理解和预测农业生态系统中农药的挥发和持久性是必要的。本研究的目的是在一系列温度和相对湿度下，以及在使用不同夏季月份收集的叶片时，测量氯吡硫磷（作为单一活性成分和农药配方）在紫花苜蓿（三叶草）叶片上的 值和叶内穿透率。使用固相逸度计测量值。一部分叶片也用于叶内穿透实验。氯吡硫磷作为单一活性成分的 值随温度降低而降低，而温度对配方中氯吡硫磷的影响可以忽略不计。未观察到 值与相对湿度之间的相关性。氯吡硫磷作为活性成分和配方的叶内穿透率均随温度升高而增加。随着温度的升高，穿透率增加是由于扩散到内层叶片的增加。挥发和叶内穿透都会影响测量的 值，因此需要了解这些过程之间的联系，以预测 值。叶片采集日期对测量的 值有很大影响，突出了需要更好地了解叶片特性对 的作用。
