Velasco Carmen A, Jarvis Jacqueline M, Tfaily Malak M, Brearley Adrian J, Holguin F Omar, Lee Carson Odell, Benavidez Angelica D, Ali Abdul-Mehdi S, Pacheco Juan S Lezama, Cabaniss Stephen E, Artyushkova Kateryna, Cerrato José M
Gerald May Department of Civil, Construction & Environmental Engineering, MSC01 1070, University of New Mexico, Albuquerque, New Mexico 87131, United States.
Department of Plant and Environmental Sciences College of Agricultural, Consumer, and Environmental Sciences, New Mexico State University, Las Cruces, New Mexico 88003, United States.
ACS ES T Water. 2025 Apr 11;5(4):1652-1662. doi: 10.1021/acsestwater.4c01004. Epub 2025 Mar 26.
Understanding oxidized uranium [U(VI)] reactions with natural organic matter (NOM) is necessary to predict the solubility and mobility of U and NOM in waters from organically rich geologic uranium deposits influenced by natural and anthropogenic processes. Here, we investigated the changes in the chemical composition of NOM resulting from its reaction with U(VI) under acidic and neutral pH under controlled laboratory conditions. We employed a multianalytical approach, including X-ray photoelectron spectroscopy (XPS), Fourier transform ion cyclotron resonance-mass spectrometry (FTICR-MS), transmission electron microscopy (TEM), and X-ray absorption spectroscopy (XAS). Results revealed that U(VI) reaction at acidic pH led to a decrease in the relative content of alcohols, carboxylic functional groups, and compounds with high O/C ratios in NOM. Our integrated analyses suggest that NOM's molecular composition is altered by two primary mechanisms: (1) selective aqueous complexation of U with alcohol and carboxylic groups in NOM and (2) U adsorption onto particulate organic matter (POM). These findings provide insights into NOM chemical transformations due to U interactions under pH conditions relevant to acid mine drainage, natural geologic deposits, and surface waters affected by legacy uranium mining.
了解氧化铀[U(VI)]与天然有机物（NOM）的反应对于预测受自然和人为过程影响的富含有机质地质铀矿床水中U和NOM的溶解度和迁移率至关重要。在此，我们在受控实验室条件下研究了在酸性和中性pH值下NOM与U(VI)反应导致的NOM化学成分变化。我们采用了多种分析方法，包括X射线光电子能谱（XPS）、傅里叶变换离子回旋共振质谱（FTICR-MS）、透射电子显微镜（TEM）和X射线吸收光谱（XAS）。结果表明，在酸性pH值下U(VI)反应导致NOM中醇、羧基官能团以及高O/C比化合物的相对含量降低。我们的综合分析表明，NOM的分子组成通过两种主要机制发生改变：（1）U与NOM中的醇和羧基进行选择性水相络合，以及（2）U吸附到颗粒有机物（POM）上。这些发现为与酸性矿山排水、天然地质矿床以及受遗留铀矿开采影响的地表水相关的pH条件下由于U相互作用导致的NOM化学转化提供了见解。
