Abstract：
Organophosphate esters (OPEs) have proven to be pervasive in aquatic environments globally. However, understanding their partitioning behavior and mechanisms at the sediment-water interface remains limited. This study elucidated the spatial heterogeneity, interfacial exchange, and diffusion mechanisms of 14 OPEs (∑14OPEs) from river to coastal aquatic system. The transport tendencies of OPEs at the sediment-water interface were quantitatively assessed using fugacity methods. The total ∑14OPEs concentrations in water and sediments ranged from 154 ng/L to 528 ng/L and 2.41 ng/g dry weight (dw) to 230 ng/g dw, respectively. This result indicated a descending spatial tendency with moderate variability. OPE distribution was primarily influenced by temperature, pH, and dissolved oxygen levels. As the carbon atom number increased, alkyl and chlorinated OPEs transitioned from diffusion towards the aqueous phase to equilibrium. In contrast, aryl OPEs and triphenylphosphine oxide, which had equivalent carbon atom counts, maintained equilibrium throughout. Diffusion trends of individual OPE congener at the sediment-water interface varied at the same total organic carbon contents (foc). As the foc increased, the fugacity fraction values for all OPE homologs showed a declining trend. The distinct molecular structure of each OPE monomer might lead to unique diffusive behaviors at the sediment-water interface. Higher soot carbon content had a more pronounced effect on the distribution patterns of OPEs. The sediment-water distribution of OPEs was primarily influenced by total organic carbon, sediment particle size, dry density, and moisture content. OPEs displayed the highest sensitivity to fluctuations in ammonium and dissolved organic carbon. This study holds significant scientific and theoretical implications for elucidating the interfacial transport and driving forces of OPEs and comprehending their fate and endogenous release in aquatic ecosystems.
摘要：
有机磷酸酯（OPEs）已被证明在全球水生环境中普遍存在。然而,了解它们在沉积物-水界面的分配行为和机制仍然有限。这项研究阐明了空间异质性，界面交换，以及14种OPEs(∑14OPEs)从河流到沿海水生系统的扩散机制。使用逸度方法定量评估了OPEs在沉积物-水界面的传输趋势。水和沉积物中的∑14OPEs总浓度范围为154ng/L至528ng/L，2.41ng/g干重（dw）至230ng/gdw，分别。该结果表明空间趋势下降，变异性适中。OPE分布主要受温度影响,pH值,和溶解氧水平。随着碳原子数的增加,烷基和氯化OPEs从扩散到水相过渡到平衡。相比之下,芳基OPEs和氧化三苯基膦，具有相等的碳原子数，始终保持平衡。在相同的总有机碳含量（foc）下，沉积物-水界面处单个OPE同源物的扩散趋势有所不同。随着FOC的增加，所有OPE同系物的逸度分数值均呈下降趋势。每个OPE单体的独特分子结构可能导致在沉积物-水界面处的独特扩散行为。较高的碳烟含量对OPEs的分布模式有更明显的影响。OPEs的沉积物-水分布主要受总有机碳的影响，沉积物粒径,干密度,和水分含量。OPEs对铵和溶解有机碳的波动表现出最高的敏感性。这项研究对于阐明OPEs的界面运输和驱动力以及理解其在水生生态系统中的命运和内源性释放具有重要的科学和理论意义。
