| 摘要: |
| [目的]研究不同类型表面活性剂对不同有机质含量土壤吸附莠去津行为的影响.[方法] 采集6种有机质含量为2.5～43 g/kg的土壤,配制一系列含一定质量浓度莠去津和6个不同质量浓度十二烷基苯磺酸钠(DBS)、十六烷基三甲基溴化铵(CTAB)和吐温20(Tween-20)溶液,用振荡平衡技术测定莠去津在水/土相间的表观分配系数Kd*(有表面活性剂)和Kd(无表面活性剂),并计算吸附的表面活性对莠去津的分配系数.[结果] 初始质量浓度为0～3 353 mg/L的CTAB能提高6种土壤对莠去津的吸附能力.当CTAB初始质量浓度为1 677 mg/L时,Kd*开始显著增加,CTAB质量浓度为3 353 mg/L时,Kd*为Kd的2～26倍;DBS和Tween-20对土壤吸附莠去津能力的影响因土壤有机质含量大小分为2类:(1)对有机质含量较高的土壤(28～43 g/kg),DBS初始质量浓度为0～400 mg/L时,其对Kd*影响不大,DBS质量浓度为500 mg/L时,Kd*减小为Kd的37%～75%;Tween-20初始质量浓度为0～10 100 mg/L时,Kd*随Tween-20质量浓度的增加先增大后减小,然后稍有增加,Kd*为Kd的0.95～1.5倍;(2)对有机质含量较低的土壤(2.5～4.0 g/kg),DBS初始质量浓度为0～500 mg/L时,Kd*和Kd均随DBS质量浓度的增加先增大后减小,且Kd*＞Kd;Tween-20初始质量浓度为0～990 mg/L时,Kd*随Tween-20质量浓度的增加而增大,当TWeen-20的质量浓度大于990 mg/L时开始明显增加,TWeen-20质量浓度为10 100 mg/L时,Kd*约为Kd的3倍.[结论] 除表面活性剂种类和质量浓度外,土壤有机质含量对莠去津在土壤中的吸附行为也有影响;吸附的表面活性剂对莠去津增溶能力的大小顺序为:CTAB>DBS>Tween-20. |
| 关键词: 莠去津 吐温20 烷基苯磺酸钠 十六烷基三甲基溴化铵 |
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| 基金项目:陕西省科技计划项目(2004K03-G3)；陕西省教育厅专项科研计划项目(04JK234) |
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| Mutual effect of surfactant and soil organic matters on the absorption of atrazine in soils |
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| Abstract: |
| 【Objective】 The objective of this study was to examine the effect of the surfactant nature and concentration on the absorption of atrazine in various soils.【Method】 Six soils that contain 2.5 to 43 mg/kg of soil organic matter (SOM) contents were used.The surfactants tested included cationic,anionic and nonionic types,with concentrations up to several times the critical micelle concentration (CMC).The batch equilibrium technique was employed to determine the distribution coefficients of atrazine in solid-water mixtures in the presence (Kd*) and absence of surfactants (Kd).A three-phase model was employed to estimate the partition coefficients of atrazine to the sorbed surfactants.【Result】 The obtained results showed that atrazine adsorption was enhanced in all soils in the presence of cationic surfactant (cetyltrimethyl ammonium bromide,CTAB),especially at the concentrations above 1677 mg/L(5 CMC).When CTAB was used with an initial concentration of 3 353 mg/L,the Kd values were increased by 2- to 26-fold.The effects of anionic surfactant (sodium dodecylbenzene sulfonate,DBS) and nonionic surfactant (Tween-20) on the atrazine adsorption behaviors could be classified into two groups with regard to soil organic matter contents.For the higher organic matter soils (28-43 g/kg OM),addition of DBS at concentration below 400 mg/L had a minor effect on Kd*,whereas addition of 500 mg/L DBS reduced Kd* to 37%-75% of the corresponding Kd values;Addition of Tween-20 at concentration below 10100 mg/L resulted in a marginal change of the Kd* values,and the ratios of Kd* to Kd varied in the range of 0.95 to 1.5.In contrast,for low organic matter soils (2.5-4.0 g/kg OM),Kd* values initially increased with increasing DBS concentration before decreasing at higher concentration,but the Kd* values were always larger than those of corresponding Kd over the whole concentration range examined;Addition of Tween 20 appreciably increased Kd* values at concentration below 990 mg/L,while 10 100 mg/L Tween-20 could enhance Kd values by 3 times.【Conclusion】 Besides surfactant type and concentration,soil organic mater contents played an important role in the effect of surfactants on atrazine adsorption in soils.The solubilization of the sorbed surfactants to atrazine decreased in the order of CTAB>DBS>Tween-20. |
| Key words: artazime tween-20 sodium dodecylbenzene sulfonate cetyltrimethyl ammonium bromide |
