Delaware Environmental Institute, Department of Plant and Soil Sciences , University of Delaware , Newark , Delaware 19716-7310 , United States.
Environ Sci Technol. 2019 Apr 16;53(8):4295-4304. doi: 10.1021/acs.est.9b00540. Epub 2019 Mar 18.
Iron (oxyhydr)oxides are highly reactive, environmentally ubiquitous organic matter (OM) sorbents that act as mediators of terrestrial and aqueous OM cycling. However, current understanding of environmental iron (oxyhydr)oxide affinity for OM is limited primarily to abiogenic oxides. Bacteriogenic iron (oxyhydr)oxides (BIOs), common to quiescent waterways and soil redox transitions, possess a high affinity for oxyanions (i.e., arsenate and chromate) and suggests that BIOs may be similarly reactive for OM. Using adsorption and desorption batch reactions, paired with Fourier transform infrared spectroscopy and Fourier transform ion cyclotron resonance mass spectrometry, this work demonstrates that BIOs are capable of sorbing leaf litter-extracted DOM and Suwannee River Humic/Fulvic Acid (SRHA/SRFA) and have sorptive preference for distinct organic carbon compound classes at the biomineral interface. BIOs were found to sorb DOM and SRFA to half the extent of 2-line ferrihydrite per mass of sorbent and was resilient to desorption at high ionic strength and in the presence of a competitive ligand. We observed the preferential sorption of aromatic and carboxylic-containing species and concurrent solution enrichment of aliphatic groups unassociated with carboxylic acids. These findings suggest that DOM cycling may be significantly affected by BIOs, which may impact nutrient and contaminant transport in circumneutral environments.
铁（氧）氢氧化物是高度反应性的、普遍存在于环境中的有机物质（OM）吸附剂，它们作为陆地和水相 OM 循环的介质。然而，目前对环境中铁（氧）氢氧化物对 OM 的亲和力的理解主要局限于非生物氧化物。细菌成因的铁（氧）氢氧化物（BIOs），常见于静止水道和土壤氧化还原过渡区，对含氧阴离子（如砷酸盐和铬酸盐）具有高亲和力，并表明 BIOs 可能对 OM 具有类似的反应性。本研究通过吸附和解吸批量反应，结合傅里叶变换红外光谱和傅里叶变换离子回旋共振质谱，证明 BIOs 能够吸附叶凋落物提取的 DOM 和苏万尼河腐殖酸/富里酸（SRHA/SRFA），并在生物矿界面上对不同的有机碳化合物类具有吸附偏好。BIOs 被发现以与 2 线水铁矿相同的质量吸附 DOM 和 SRFA 的一半，并且在高离子强度和存在竞争配体的情况下对解吸具有弹性。我们观察到芳香族和含羧基的物质优先吸附，同时与羧酸无关的脂肪族基团在溶液中富集。这些发现表明，DOM 循环可能会受到 BIOs 的显著影响，这可能会影响中性环境中营养物质和污染物的运输。
