连作杨树人工林根际土壤中2种酚酸的吸附与解吸行为

Sorption-Desorption of Two Phenolic Acids in Poplar Rhizosphere Soil in Continuous Cropping Plantation

采集不同代人工林林地杨树根际土壤样品,采用等温吸附和解吸试验结合HPLC定量测定,研究杨树根际土壤中2种主要酚酸(对羟基苯甲酸和苯甲酸)的吸附和解吸附特性,探讨2种酚酸在杨树根际土壤中的累积机制。结果表明:杨树根际土壤对对羟基苯甲酸和苯甲酸均具有较强的吸附能力,对羟基苯甲酸的平均吸附率63.39%～72.26%,苯甲酸的吸附率较对羟基苯甲酸低,平均吸附率39.53%～47.46%;Fruendlich等温吸附方程能很好地描述这2种酚酸在杨树根际土壤中的吸附过程,吸附平衡浓度Ce和吸附量Cs之间存在较好的线性关系。2种酚酸的吸附作用属于物理吸附,但解吸特性差异较大,对羟基苯甲酸在不同连作代数林地根际土壤吸附平衡液中的解吸能力均较强,平均解吸率46.62%～52.89%;而苯甲酸解吸能力较弱,尤其在高浓度吸附平衡体系中很难进行解吸附,此规律与2种酚酸的吸附常数基本吻合。2种酚酸的吸附和解吸特性一定程度上反映酚酸在杨树根际土壤中的环境行为学特征,并为进一步揭示其在杨树根际微域的累积机制提供理论依据。

Sorption and desorption characteristics of two phenolic acids, p-hydroxybenzoic acid and benzoic acid, in the rhizosphere soil of continuous cropping poplar plantations were investigated in order to find accumulation mechanism of the phenolic acids. An isotherms adsorption and desorption method and HPLC test were used. The results showed that rhizosphere soil of poplar plantation had strong adsorptive capacity to p-hydroxybenzoic acid and benzoic acid. The average adsorption rate of benzoic acid in the rhizosphere soil acid was from 39.53% to 47.46% , which was lower than that of phydroxybenzoic acid with an average adsorption rate from 63.39% to 72.26%. Fruendlich isotherms adsorption equation well described the adsorption process of those two phenolic acids in poplar rhizosphere soil, and there existed a significant linear relation between Co （ adsorption equilibrium concentration） and C （absorbance）. The adsorption of those two phenolic acids belonged to physical adsorption. But, p-hydroxybenzoic acid had a stronger desorption capacity in different poplar plantation rhizosphere soil and the average desorption rate was from 46.62% to 52. 89%. In comparison, the desorption rate of benzoic acid was lower, especially in balanced adsorption solution at high concentration. This rule was in accordance with the adsorption constant in the rhizosphere soil of different poplar generation. The sorption and desorption of those two phenolic acids reflected the property of environmental behavior in rhizosphere soil and could interpret accumulation of the phenolic acids in poplar rhizosphere soil.