双酚S及双酚A在云南典型耕作土壤上的吸附机制

Adsorption mechanism of bisphenol S and bisphenol A on typical cultivated soil in Yunnan Province

近年来,双酚S(BPS)作为双酚A(BPA)的替代物被大量引入土壤环境,研究发现BPS具有与BPA类似的内分泌干扰效应,亟需开展工作研究BPS在土壤中的环境行为.本研究选取云南元阳、蒙自两地区耕作前后的土壤样品,通过批量吸附实验研究BPS以及BPA在云南典型耕作土壤中的吸附机制.结果表明, Freundlich模型能较好拟合BPS和BPA在土壤上的吸附等温线(r^(2)adj:0.953-0.997),且表现出较高的非线性吸附.吸附系数Kd与土壤有机碳(f_(oc))呈显著正相关,表明BPS和BPA在土壤上的吸附以憎水性作用为主.排除憎水性作用后,BPA在土壤上的吸附高于BPS是由于BPA与土壤有机质之间的电子供-受体作用强于BPS所导致的.蒙自耕作土壤中(MP)三七根所分泌的有机酸可能会破坏土壤矿物结构而导致土壤有机质有所降低,但有机酸分子中的羧基可增强土壤的电子受体能力,使得BPA与MP土壤之间形成强烈的电子供-受体作用而使其吸附增强.

Bisphenol S has been introduced into the soil environment as a substitute for Bisphenol A. However, studies have shown that BPS has similar estrogenic activity as BPA, and it is essential to investigate the environmental behavior of BPS in soil. The native and cultivated soil in Yuanyang and Mengzi of Yunnan were collected, and the adsorption mechanism of BPS and BPA on typical native and cultivated soil in Yunnan was studied through batch adsorption experiments. The results showed that the Freundlich model could well fit the adsorption isotherms of BPS and BPA on soils(r^(2) adj: 0.953-0.997), and the adsorption isotherms exhibited significant nonlinear. The adsorption coefficient Kd is significantly positive correlated with soil organic carbon(f_(oc)), indicating that the adsorption of BPS and BPA on the soils is dominated by hydrophobicity effect. Higher adsorption of BPA on soils than that of BPS when hydrophobic effects were excluded is owing to the electron donor-acceptor interaction between BPA and soil organic matter is stronger than that of BPS. The organic acids secreted by the roots of Notoginseng in Mengzi tillage soil(MP) may destroy the soil mineral structure and then lead to a decrease in soil organic matter. However, the carboxyl groups in the organic acid molecules can enhance the electron-donating ability of the MP, then strengthen the electron donor-acceptor interaction between BPA and MP, resulting in higher adsorption of BPA than BPS on MP.