壬基酚在土壤中的吸附和淋溶特性

Adsorption and Leaching of Nonylphenol in Soils

为探究壬基酚在土壤中的吸附迁移规律,分别采用振荡平衡法和柱淋溶法研究了壬基酚在南京黄棕壤、江西红壤、常熟乌栅土、太湖水稻土、东北黑土5种不同土壤中的吸附特性、移动特性,并通过比较其在不同土壤中的吸附和淋溶来分析壬基酚在土壤中吸附和淋溶性的影响因素。吸附试验表明,壬基酚在南京黄棕壤、江西红壤、常熟乌栅土、太湖水稻土、东北黑土中的吸附性均较符合Freundlich方程,Kd值分别为18.89、26.64、44.15、47.49、69.92;吸附性大小次序为:南京黄棕壤<江西红壤<常熟乌栅土<太湖水稻土<东北黑土;以有机碳含量表示的土壤吸附常数KOC在2 534.50~4 860.65之间;影响壬基酚土壤吸附性的主要因素为土壤有机质含量,土壤有机质含量增加,吸附增强;壬基酚在5种土壤中的吸附自由能为-21.02^-19.77 k J·mol^(-1),表明吸附机理主要是物理吸附。土柱试验表明,壬基酚在土壤中具有难淋溶性质,壬基酚在5种供试土壤的1~3 cm深度的淋溶滞留量最大;影响其在土壤中淋溶性的主要因素为土壤有机质含量,与吸附试验相一致。壬基酚在土壤中易吸附难淋溶,移动性弱的特点对地表土壤层具有潜在的污染风险,应该引起足够重视。

The adsorption and leaching of nonylphenol in five soils collected from China were examined through batch equilibrium and column leaching tests to understand the mobility of nonylphenol in soils.Besides,the main factors governing the absorption and leaching in different soils were identified.Adsorption results showed that the adsorption of nonylphenol onto tested soils fits well with Freundlich model,and the adsorption coefficient(K_d) was 18.89 for Nanjing yellow-brown soil,26.64 for Jiangxi red soil,44.15 for Changshu orchard soil,47.49 for Taihu paddy soil,and 69.92 for Northeast China black soil,respectively.The adsorption capacity ranked as Nanjing yellow-brown soil < Jiangxi red soil < Changshu orchard soil < Taihu paddy soil < Northeast China black soil.The adsorption of nonylphenol onto soil was primarily related to the organic carbon in soils.The K_d values of nonylphenol increased with the increase of organic carbon in soil.Moreover,the adsorption free energy of nonylphenol in tested soils ranked from-21.02 to-19.77 kJ·mol^(-1),indicating that the adsorption process could be largely attributed to the physical adsorption.Column test showed that the motion of nonylphenol was insignificant,and the nonylphenol moved a distance of 1~6 cm in Nanjing yellow-brown soil and 1~3 cm in other soils.The result of mobility test showed that nonylphenol did not leach out.The soil organic matter content in soils was a dominant factor influencing the mobility of nonylphenol,which was in accordance with the adsorption results.This study demonstrates that nonylphenol has potential risk of contaminating the surface soil layer,which should be paid more attention.