外源木炭对异丙隆在土壤中吸附-解吸的影响

Influences of Charcoal Amendment on Adsorption-Desorption of Isoproturon in Soils

【目的】研究除草剂异丙隆在木炭上的吸附-解吸规律,探讨外源木炭对减少异丙隆从土壤中流失的作用机制,为土壤-水环境中农药的污染防治提供依据。【方法】采用振荡平衡法,研究了异丙隆在5个不同粒径木炭和3种不同类型土壤中的吸附-解吸特征。【结果】异丙隆在木炭和土壤中的吸附-解吸均符合Freundlich方程。木炭对异丙隆有很强的吸附能力,木炭粒径越小,对异丙隆的吸附能力越强。添加木炭能够显著提高土壤对异丙隆的吸附量,木炭添加量越多,异丙隆吸附量越大,木炭添加量与异丙隆吸附量呈显著正相关(相关系数r=0.9568**)。异丙隆在木炭和土壤中的解吸过程均存在明显的滞后效应,且这种滞后效应随着木炭添加量的增大而逐渐加强。环境扫描电镜(ESEM)分析显示,木炭具有疏松多孔结构,对异丙隆具有较强的物理吸附能力。红外光谱(FTIR)分析结果表明,异丙隆可能通过氢键或范德华力与木炭结合。【结论】以木炭作为人工添加吸附剂可有效地减少异丙隆从土壤中的流失。

[Objective] In order to prevent pesticide leaching from soil, the effects of charcoal amendment on adsorptiondesorption of isoproturon in soils were studied and the mechanisms in reducing the loss of isoproturon from soils were suggested. [Method] Adsorption-desorption of isoproturon in five different particle sizes of charcoals and three different soils were studied using batch equilibration technique. [ Result] The results showed that the experimental data were fitted by the Freundlich empirical equation. Charcoal had a great adsorption capacity for isoproturon, and the smaller the particle size of the charcoal, the more the adsorption of isoproturon. The amendment with charcoal improved the adsorption of isoproturon in soils. The adsorption of isoproturon in soils increased with the rate of charcoal amended （correlation coefficient r=0.9568^＊＊, P〈Z0.01）. Desorption of isoproturon from charcoals and soils showed significant hystersis effect which was shown by the higher adsorption slope （1/ndas） compared to the desorption slope （1/ndes）. The hysteresis effects of charcoal on desorption of isoproturon were closely correlated with the content of charcoal in the soils, and the hysteresis index （H） increased with the rate of charcoal amended. Observation of environment scanning electron microscope （ESEM） exhibited the fine pore structure and special surface characteristics of the tested charcoal. Analysis of Fourier transform infrared spectra （FTIR） of isoproturon adsorbed on charcoal suggested probable bonding interactions between isoproturon and charcoal, [ Conclusion ] Charcoal amendment may be an effective management practice for controlling pesticide desorption and leaching in soils.