Influence of dissolved organic matter on sorption of 2,4-dichlorophenoxyacetic acid in ferralsol
WU Dong-ming;REN Chang-qi;LI Qin-fen;WU Chun-yuan;LI Wei;Institute of Environment and Plant Protection,Chinese Academy of Tropical Agricultural Sciences;Danzhou Scientific Observing and Experimental Station of Agro-Environment,Ministry of Agriculture;Academy of Tropical agriculture and forestry,Hainan University;
In this study,the sorption kinetics and isotherms of 2,4-dichlorophenoxyacetic acid(2,4-D) in three ferralsols were investigated,and the effect of dissolved organic matters(DOMs) was compared.The results showed that the sorption kinetics of 2,4-D in ferralsols followed Pseudo first-order equation,and the isotherm data were fitted well by Henry and Freundlich model,indicated that 2,4-D sorption on the ferralsols was an spontaneous,exothermic and anisotropic process dominated 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 difficult to be sorbed by the soils,which could result environmental risk to the groundwater.The sorption of 2,4-D in the ferralsol was significantly affected by the soil p H 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 in ferralsols were closely associated with both characteristics of DOM and soil.The effect of soil pore blocking increased with the increase of the soil mineral components and the clay contents.Meanwhile,with the increase of the hydrophobicity of DOM,the effect of solubility enhancement and pore blocking increased,which decreased the 2,4-D sorption in the ferralsols.The hydrophobiv acid fraction(HOA) and hydrophobic neutral fraction(HON) were the key fractions for this process.
【Fund】： 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)
【CateGory Index】： X592
【CateGory Index】： X592