Morillo Esmeralda, Maqueda Celia, Reinoso Rocío, Undabeytia Tomás
Instituto de Recursos Naturales y Agrobiología de Sevilla (CSIC), Seville, Spain.
Environ Sci Technol. 2002 Oct 15;36(20):4319-25. doi: 10.1021/es0200443.
The influence of two organic amendments on norflurazon sorption-desorption processes in four soils with very different physicochemical characteristics was studied in laboratory experiments to evaluate the potential leaching of this pesticide through organic fertilized soils. Sorption-desorption experiments were performed on original soils and on a mixture of these soils with urban waste compost (SUW) and a commercial amendment from olive-mill wastes (OW), at a rate of 6.25% (w/w). These mixtures were used immediately after preparation and after aging for 2 months. Norflurazon was analyzed by using a HPLC method. Norflurazon retention in original soils was related not only to the organic matter (OM) content but also to mineral surfaces present in soils. Norflurazon sorption increases largely after amendment in soils with low OM content, but the addition of exogenous OM to soils with medium OM content and/or other available adsorptive surfaces did not significantly affect norflurazon sorption. Even in some cases pesticide sorption decreases, due to the blocking of the mineral and organic soil surfaces with the amendment added. Transformation of exogenous OM during incubation depends both on the amendment added and on the type of soil and can affect sorption-desorption behavior of the soils surfaces in different manner, due to the modification of their hydrophobic-hydrophilic characteristics. Norflurazon desorption from original soils showed hysteresis in all cases, but it was not affected or even decreased in amended soils. It was a nonexpected behavior, especially in sandy soil, since it is generally assumed that a higher sorption always implies a lower mobility in soils. Norflurazon sorption must be taking place on very low affinity sites on exogenous OM through weak bindings, from which the pesticide can be easily desorbed. The application to soils of the organic amendments used in the present study could not be accepted to reduce norflurazon losses due to leaching processes.
在实验室实验中，研究了两种有机改良剂对四种理化性质差异很大的土壤中氟乐灵吸附 - 解吸过程的影响，以评估该农药通过有机施肥土壤潜在的淋溶情况。在原始土壤以及这些土壤与城市垃圾堆肥（SUW）和一种来自橄榄渣的商业改良剂（OW）以6.25%（w/w）比例混合的土壤上进行吸附 - 解吸实验。这些混合物在制备后立即使用，并在老化2个月后使用。采用高效液相色谱法分析氟乐灵。氟乐灵在原始土壤中的保留不仅与有机质（OM）含量有关，还与土壤中存在的矿物表面有关。在低OM含量的土壤中添加改良剂后，氟乐灵的吸附大幅增加，但向中等OM含量的土壤和/或其他可用吸附表面添加外源OM对氟乐灵吸附没有显著影响。甚至在某些情况下，由于添加的改良剂堵塞了矿物和有机土壤表面，农药吸附会降低。孵化过程中外源OM的转化既取决于添加的改良剂，也取决于土壤类型，并且由于其疏水 - 亲水特性的改变，会以不同方式影响土壤表面的吸附 - 解吸行为。氟乐灵从原始土壤中的解吸在所有情况下都表现出滞后现象，但在改良土壤中不受影响甚至降低。这是一种意想不到的行为，尤其是在沙质土壤中，因为通常认为较高的吸附总是意味着在土壤中的迁移性较低。氟乐灵的吸附一定是通过弱结合在外源OM上的非常低亲和力位点发生的，农药可以很容易地从这些位点解吸。本研究中使用的有机改良剂应用于土壤不能被接受用于减少氟乐灵因淋溶过程造成的损失。
