Microbial extracellular polymeric substances (EPS) represent an important source of labile component in natural organic matter (NOM) pool. However, the sorption behavior of EPS to mineral surfaces and associated effects on sorption of hydrophobic organic contaminants (HOCs) are not well understood. Here, we systematically investigated the fractionation of EPS extracted from two different microbial sources (Gram-positive B. subtilis and Gram-negative E. coli) during sorption to montmorillonite, kaolinite, and goethite using collective characterization methods (SEM, electrophoretic mobility, FTIR, UV-vis, fluorescence, and size exclusion chromatography). The peptide-like substances and acidic components with high aromaticity in B. subtilis EPS were more preferentially sorbed than those fractions in E. coli EPS by the three minerals, especially by goethite. Additionally, goethite sorbed more negatively charged and lower molecular weight fractions compared to montmorillonite. The presorption of EPS (1.68–3.79% organic carbon) on the three minerals increased the sorption distribution coefficient (K_d) of phenanthrene (a model apolar HOC) by 2.83–5.29 times, depending on the EPS-mineral complex. All the six examined EPS-mineral complexes exhibited approximately one order of magnitude larger organic carbon (OC)-normalized sorption coefficient (K_OC) than the two pristine EPS, indicating that the sorptive interactions were pronouncedly facilitated by the sorbed EPS on mineral surfaces. Thus, the type and surface property of minerals as well as the biological source of EPS are key determinants of sorption fractionation of EPS on minerals and in turn affect sorption affinity of apolar HOCs to EPS-mineral complexes.

微生物细胞外聚合物（EPS）是天然有机物（NOM）库中不稳定成分的重要来源。然而，EPS对矿物表面的吸附行为以及对疏水性有机污染物（HOC）吸附的相关影响尚不十分清楚。在这里，我们使用集体表征方法（SEM，电泳迁移率，FTIR）系统地研究了从两种不同微生物来源（革兰氏阳性枯草芽孢杆菌和革兰氏阴性大肠杆菌）吸附到蒙脱石，高岭石和针铁矿中的EPS的分级分离，紫外可见，荧光和尺寸排阻色谱）。枯草芽孢杆菌中具有高芳香性的肽样物质和酸性成分三种矿物质（尤其是针铁矿）比大肠杆菌EPS中的那些组分更优先吸附EPS。另外，与蒙脱石相比，针铁矿吸附的负电荷更大，分子量分数更低。三种矿物上EPS的预吸附（1.68–3.79％的有机碳）使菲（非极性HOC模型）的菲的吸附分布系数（K _d）增加2.83–5.29倍，具体取决于EPS-矿物的复合物。所检查的所有六个EPS-矿物络合物均显示出约大一个数量级的有机碳（OC）归一化吸附系数（K _OC），而不是两个原始EPS，表明在矿物表面上吸附的EPS明显促进了吸附相互作用。因此，矿物的类型和表面性质以及EPS的生物来源是EPS在矿物上吸附分级的关键决定因素，进而影响非极性HOC对EPS-矿物复合物的吸附亲和力。