溶解性有机质对铁铝土吸附2,4-D的影响  

Influence of dissolved organic matter on sorption of 2,4-dichlorophenoxyacetic acid in ferralsol

作　　者：吴东明[1,2] 任常琦 李勤奋 武春媛[1,2] 李玮[1,2] 

机构地区：[1]中国热带农业科学院环境与植物保护研究所,海南海口571101 [2]农业部儋州农业环境科学观测实验站,海南儋州571737 [3]海南大学热带农林学院,海南海口570228

出　　处：《中国环境科学》2018年第3期1090-1098,共9页China Environmental Science

基　　金：公益性行业(农业)科研专项(有机化学品污染农田和农产品质量安全综合防治技术方案)子课题(201503107-14);国家自然科学基金资助项目(41371465);海南省重大科技计划(ZDKJ2017002);中国热带农业科学院创新团队项目(1630022017009)

摘　　要：以动力学吸附和等温吸附实验研究了2,4-D在铁铝土中的吸附特征,并比较了不同亲/疏水性溶解性有机质(DOM)对此的影响.结果表明:2,4-D在铁铝土中的动力学吸附符合伪一级动力学方程,等温吸附符合Henry,Freundlich方程,是一个物理作用主导的,自发的,放热的非均质吸附过程.吸附系数Kd为0.61~2.02L/kg,是一种难吸附有机污染物,对地下水存在环境风险.吸附量受土壤p H值影响显著,与土壤中矿物含量,粘粒组成等也密切相关.DOM共存条件下,高疏水性DOM,中疏水性DOM抑制了2,4-D在铁铝土的吸附,使Kd值下降10.7%~58.8%.低疏水性DOM对铁铝土吸附2,4-D作用不明显.DOM对铁铝土吸附2,4-D的作用效应与土壤理化性质和DOM性质密切相关.土壤矿物组分越多,粘粒含量越高,堵孔效应越大.DOM疏水性越大,对2,4-D吸附作用的增溶作用,堵孔作用也越大,其中HOA,HON是关键组分.In this study, the sorption kinetics and isotherms of 2, 4-dichlorophenoxyacetic acid （2, 4-D） in three ferralsolswere investigated, and the effect of dissolved organic matters （DOMs） was compared. The results showed that the sorptionkinetics of 2, 4-D in ferralsols followed Pseudo first-order equation, and the isotherm data were fitted well by Henry andFreundlich model, indicated that 2,4-D sorption on the ferralsols was an spontaneous, exothermic and anisotropic processdominated by physical forces. The value of Kd for 2, 4-D ranged from 0.61 to 2.02 L/kg, implying that 2, 4-D was difficultto be sorbed by the soils, which could result environmental risk to the groundwater. The sorption of 2, 4-D in the ferralsolwas significantly affected by the soil pH values, and was also closely related to the content of mineral and clay. Moreover,in the presence of dissolved organic matter, DOM with high hydrophobicity （CC） and DOM with medium hydrophobicity（SPd） inhibited 2, 4-D sorption on the three ferralsols, causing the Kd values decreased by 10.7%~58.8%. Conversely,there was no significant effect by DOM with low hydrophobicity （RS）. The influence of DOM on the sorption of 2, 4-D inferralsols were closely associated with both characteristics of DOM and soil. The effect of soil pore blocking increasedwith the increase of the soil mineral components and the clay contents. Meanwhile, with the increase of thehydrophobicity of DOM, the effect of solubility enhancement and pore blocking increased, which decreased the 2, 4-Dsorption in the ferralsols. The hydrophobiv acid fraction （HOA） and hydrophobic neutral fraction （HON） were the keyfractions for this process.

关 键 词：2 4-二氯苯氧乙酸 铁铝土 溶解性有机质 吸附 

分 类 号：X502[环境科学与工程—环境工程]