## 1 Introduction  
Uranium (U) can be present in rock and soil matrices and redistributed in the environment, both naturally and anthropogenically [1]. The most relevant oxidation states of uranium in nature are two: U(IV), which appears in the insoluble oxide UO\({}_{2}\), and U(VI), which forms the uranyl ion (UO\({}_{2}\))\({}^{2+}\) and forms water-soluble compounds [2].  
The transport of U occurs through its release into the surrounding environment, through mining activities, radioactive waste, or nuclear accidents, among others [1]. Abandoned uranium deposits, a global issue, exist in the Americas, Europe, Asia, and Africa [3], now regarded as a legacy of the nuclear energy boom of the 20 th century. The transport of uranium in these deposits is studied as a requirement for remediation work. There are frequent publications on transport in humid environments and groundwater [4; 5]. Likewise, Transport studies have recently been conducted in rock piles from abandoned uranium mines [6; 7]. On the other hand, many abandoned deposits are located in more or less arid territories in Argentina, Australia, Spain, the United States, and the former Soviet Union, among others. However, the study of the surface transport of uranium in arid areas is a significantly underexplored area in the scientific literature, with only a few scattered references [8; 9; 10]. This scarcity underscores the need for more research in this field.  
Experiments have been carried out at different scales to determine the magnitude of uranium transport and interaction at contaminated sites. Among them, transport in sediment-packed columns stands out. For example, using vertical columns with saturated flow and an upward direction [11], investigated the leaching of U-contaminated sediments. In [11], discrete U-containing particles and U-rich areas were identified by SEM, and EDS analysis revealed that the U-containing phases contained U, Si, Ca, and Fe. Complex intergrowths between U-containing solids and aluminosilicates were observed. Analysis of the U-rich zones by X-ray absorption near edge spectroscopy (XANES) showed that uranium was in the oxidized U(VI) state. Extended X-ray absorption fine structure spectroscopy (EXAFS) indicated the possible coexistence of uranyl silicate precipitates and adsorbed uranyl. Applying these methods, in [11], they demonstrated that the release of U from particles is limited by the dissolution kinetics from the uranyl phases, showing a slow transport from the solid phase to the liquid in the pores. Likewise, in [12], the authors studied the potential for the production of U(IV) colloids from solid U(VI) phases under reducing conditions and under U biogeochemistry in dynamic systems using metaschoepite (UO\({}_{3}\cdot\)nH\({}_{2}\)O) horizons. After 6 and 12 months of reaction in two vertical columns fed in the bottom-up direction, the sediments were extracted. Bulk, \(\mu\)- and nano-focusing X-ray absorption spectroscopy (XAFS) and X-ray fluorescence (XRF) analyses were applied to track changes in solid U speciation over time. In [13], with 20 sediment columns and up-flow, an effluent and solids analysis was performed, and geochemical modeling was performed to determine uranium reactive transport in an abandoned uranium mine in Grand Junction, Colorado. The work [14] studied the transport of uranium from metaschoepite in different particle sizes in columns fed with rainwater. The sediments from the reactors were examined using autoradiography, \(\mu\)-XRF mapping, U \(\mu\)-XANES, and bulk EXAFS to track uranium migration and speciation. The authors in [15] studied the penetration of \({}^{134}\)Cs, using vertical columns fed with a radioactive solution, determining the K\({}_{\text{d}}\) values for the different particle sizes of the sediments studied.