Natural organic matter (NOM) has long been shown to be the dominant factor in determining equilibrium and kinetic processes during sorption and desorption phenomena in sediment and soil experiments. Although several models have been suggested for predicting these processes, few offer mechanistic interpretations because the spatial location of organic matter on sediment particles is unknown. This investigation manually examined sediment particles from multiple locations, containing varying concentrations of NOM, using scanning electron microscopy with energy dispersive X‐ray spectroscopy to determine the types of particles present by categorizing them as individual particles, aggregates, and “other” (detritus, algae, etc.). These types of particles were subsequently analyzed for their elemental composition, specifically the spatial location of carbon. By creating a carbon map of each particle, this investigation has determined that organic matter tends to occur in 2 forms: large aggregates or dispersed across individual sediment particles. These findings were then used to propose a more mechanistically sound mathematical model for pollutant desorption phenomena, assigning the traditional labile kinetic release component to the dispersed NOM spread randomly across sediment particles and the nonlabile kinetic release component to diffusion from densely packed NOM aggregates. Environ Toxicol Chem 2021;40:323–332. © 2020 SETAC

中文翻译：

---

通过扫描电子显微镜分析沉积物颗粒上天然有机物的空间分布和位置以及一种新的持久性有机污染物——沉积物动力学解吸模型的发展

长期以来，天然有机质 (NOM) 一直被证明是在沉积物和土壤实验中的吸附和解吸现象中决定平衡和动力学过程的主要因素。尽管已经提出了几种模型来预测这些过程，但很少提供机械解释，因为沉积物颗粒上有机物质的空间位置是未知的。这项调查手动检查了来自多个位置的沉积物颗粒，这些颗粒含有不同浓度的 NOM，使用扫描电子显微镜和能量色散 X 射线光谱仪来确定存在的颗粒类型，方法是将它们分类为单个颗粒、聚集体和“其他”（碎屑、藻类等）。随后分析了这些类型的颗粒的元素组成，特别是碳的空间位置。通过创建每个颗粒的碳图，这项调查确定有机物质往往以两种形式出现：大聚集体或分散在单个沉积物颗粒中。然后，这些发现被用来为污染物解吸现象提出一个更机械合理的数学模型，将传统的不稳定动力释放成分分配给随机分布在沉积物颗粒上的分散 NOM，将不稳定动力释放成分分配给从密集堆积的 NOM 聚集体扩散。环境毒理学化学2021；40：323-332。© 2020 SETAC