Elucidating how organic matter and iron oxide particles interact will advance the understanding of geochemical processes and facilitate the development and implementation of methods to address groundwater pollution. The sorption and fractionation of three well-characterized organic matter isolates, Suwannee River natural organic matter (SRNOM), Suwannee River fulvic acid (SRFA), and Eliot Soil humic acid (ESHA), onto goethite nanoparticles in batch reactors and goethite-coated sand in column reactors were studied. Total organic carbon, molecular size, and optical properties were measured before and after exposure to solids in batch and column reactors, as well as in solution after the resuspension of equilibrated solids in a fresh buffer. Fluorescent, aromatic, high-molecular-weight material more strongly sorbed and stayed sorbed upon exposure to fresh solution. The effects of the different organic matter fractions on reduction of 4-chloronitrobenzene (4-ClNB) were also quantified. In both batch and column reactors, the reactivity of NOM-treated particles toward 4-ClNB in the presence of Fe(II) was inhibited by all isolates as compared to that in NOM-free reactors, with SRFA inhibiting reaction rate constants the most followed by ESHA and SRNOM. There are clear spectral and size differences in the organic matter that remains in the liquid medium compared to the NOM that binds to the mineral surfaces, but both of these materials inhibit Fe(II)-mediated reactions on the surface. Materials high in aliphatic and carboxylate contents, rather than the more strongly sorbing fluorescent aromatic material, appear to inhibit reactivity.

中文翻译：

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针铁矿与天然有机物的相互作用：分馏及其对污染物减少的影响

阐明有机物和氧化铁颗粒如何相互作用将增进对地球化学过程的理解，并促进解决地下水污染方法的开发和实施。三种特征良好的有机物分离物，苏万尼河天然有机物 (SRNOM)、苏万尼河黄腐酸 (SRFA) 和艾略特土壤腐植酸 (ESHA)，在间歇反应器和针铁矿包覆砂中的针铁矿纳米粒子上的吸附和分馏在塔式反应器中进行了研究。在间歇式和柱式反应器中暴露于固体之前和之后，以及在新鲜缓冲液中重新悬浮平衡固体后的溶液中测量总有机碳、分子大小和光学性质。荧光、芳香族、高分子量材料被更强地吸附，并在暴露于新鲜溶液时保持吸附状态。还量化了不同有机物组分对 4-氯硝基苯 (4-ClNB) 还原的影响。在间歇式和柱式反应器中，与不含 NOM 的反应器相比，在存在 Fe(II) 的情况下，NOM 处理过的颗粒对 4-ClNB 的反应性均受到所有分离物的抑制，其中 SRFA 抑制反应速率常数最多由 ESHA 和 SRNOM 制定。与结合到矿物表面的 NOM 相比，保留在液体介质中的有机物存在明显的光谱和尺寸差异，但这两种材料都会抑制表面上 Fe(II) 介导的反应。脂肪族和羧酸盐含量高的材料，而不是吸收性更强的荧光芳香族材料，似乎会抑制反应性。