The long-term groundwater contamination risks posed by steroidal estrogens (SEs) in animal-manured agricultural soils are closely associated with the soil organic matter (SOM) content and composition. In this study, the bioavailability of estrone (E1) and 17β-estradiol (17β-E2) under different sorption mechanism in humic acids (HA1 and HA2) and humin (HM) extracted with sequential alkaline-extraction technique (SAET) were examined. These SOMs extracted by SAET showed various properties and sorption characteristics for SEs. The alkyl carbon and condensed SOM increased during SAET, but aromatic carbon decreased and the same trend for polarity. Quick sorption was the major SEs sorption mechanism on HA1 and HA2, which contributed more than 69%; whilst slow sorption rate was about 50% in soil and HM. The logK_oc values were proportional to the TOC of SOM according to Freundlich fitting, and the sorption capacity of sorbent for E1 and 17β-E2 was related to the logK_ow values, indicating that the main mechanism controlling the SEs sorption was hydrophobic interaction. The larger micropore volume of HM and soil was more conducive to the micropore filling of SEs. Meanwhile, the specific sorption of SEs on condensed domain of SOM was the main reason for the strong desorption hysteresis and slow sorption in HM and soil. The SEs degradation rate was positively correlated with the contribution rate of quick adsorption and negatively correlated with the contribution rate of slow adsorption, indicating that the bioavailability of SEs sorbed by hydrophobic interaction was higher than that of micropore filling or specific sorption, which was also the reason for the low bioavailability of SEs in HM and soil. This work confirms the regulation of on-site SOM compositions and their properties on SEs sorption and bioavailability. Characterization of these details is crucial for the improved prediction of long-term risks to groundwater.

由畜牧业土壤中的甾体雌激素（SEs）造成的长期地下水污染风险与土壤有机质（SOM）的含量和组成密切相关。在这项研究中，研究了不同吸附机制下雌酮（E1）和 17β-雌二醇（17β-E2）在用顺序碱提取技术（SAET）提取的腐植酸（HA1 和 HA2）和腐殖质（HM）中的生物利用度。SAET 提取的这些 SOM 显示了 SEs 的各种特性和吸附特性。SAET期间烷基碳和缩合SOM增加，但芳香碳减少，极性趋势相同。快速吸附是 SEs 对 HA1 和 HA2 的主要吸附机制，贡献率超过 69%；而在土壤和 HM 中的缓慢吸附率约为 50%。日志K _oc根据 Freundlich 拟合值与 SOM 的 TOC 成正比，吸附剂对 E1 和 17β-E2 的吸附能力与 log K _ow相关值，表明控制 SEs 吸附的主要机制是疏水相互作用。HM和土壤的微孔体积越大，越有利于SEs的微孔填充。同时，SEs在SOM凝聚域上的特异性吸附是造成HM和土壤中解吸滞后强、吸附缓慢的主要原因。SEs降解率与快速吸附贡献率呈正相关，与慢速吸附贡献率呈负相关，表明疏水相互作用吸附的SEs的生物利用度高于微孔填充或特异性吸附，这也是HM和土壤中SEs生物利用度低的原因。这项工作证实了现场 SOM 成分的调节及其对 SEs 吸附和生物利用度的特性。这些细节的表征对于改进对地下水长期风险的预测至关重要。