Aeolian sediments physicochemical properties along the Qinghai–Tibet Railway

Frequent and complex aeolian activity along the Qinghai–Tibet Railway (QTR) has resulted in substantial deposition of aeolian sediments along the corridor. To investigate the physicochemical properties of these sediments, this study combined historical meteorological data and aeolian sediment samples from three typical landform types along the QTR. The aim was to reveal regional aeolian dynamics, sedimentary attributes, and their interaction mechanisms. Aeolian activity was mainly concentrated in the Wudaoliang–Amdo section, where the mean annual wind speed at Wudaoliang reached 5.4 m/s. Sediment characteristics varied among landform types: desertified grasslands exhibited the highest stability with a mean grain size of 3.83 Φ, while sand surfaces and the Gobi Desert showed greater variability. Soil organic matter was highest in desertified grasslands (1.41 g/kg). However, soil nutrients along the railway displayed high spatial variability, with the coefficient of variation of total nitrogen (TN) on sand surfaces reaching 133.1 %. Phosphorus and potassium were generally deficient; for example, total phosphorus content in sand surface sediments ranged only from 0.22 to 0.68 g/kg, potentially hindering ecological restoration. TN was identified as an important nutrient parameter. Overall, the distribution of soil nutrients was significantly influenced by soil salinity, but nutrient interactions were stronger in desertified grasslands. Redundancy analysis identified dominant drivers of soil nutrients: fine particles acted as the primary factor on sand surfaces, whereas total salt content dominated desertified grasslands and Gobi Desert samples, explaining over 70 % of the variation. In desertified grasslands, nutrient patterns were indirectly shaped by vegetation, whereas in the Gobi Desert they were influenced by salinity, topography, and sediment sources. These findings provide a solid basis for designing and optimizing aeolian protection systems along the QTR and offer guidance for ecological restoration along alpine railway corridors.