Remotely sensed spatiotemporal dynamics of soluble salts and their natural and anthropogenic drivers in hyper-arid basins.

Soil salinization, driven by the accumulation of soluble salts, poses a significant threat to ecosystem health and agricultural productivity in arid and semi-arid regions, representing a major environmental issue on a global scale. To address critical knowledge gaps regarding salt dynamics in hyper-arid basins, this study integrates Landsat 8 OLI/TIRS, Sentinel-2, and ASTER GDEM data with 128 surface soil samples collected from the Qaidam Basin between January and October 2024, systematically investigating the spatiotemporal distribution of soluble salts. The study further quantifies the relative contributions of natural and anthropogenic sources to ecological geochemical feedbacks, defined as the interactions among soil salinization, vegetation degradation, and groundwater dynamics. Results indicate that soluble salt minerals in the surface soil-primarily halite and gypsum-account for an average of 8.82%, while water-soluble ions-mainly Na⁺, Cl⁻, Ca²⁺, and SO₄²⁻-reach 9.76 wt%. Natural sources, such as salt lake evaporation, contribute approximately 85% of the salinity in the core lake areas, whereas anthropogenic sources, including irrigation, lead to a roughly 30% enrichment of NO₃⁻ in oasis regions. The study also reveals a radial salt distribution pattern driven by wind-water coupling: halite accumulates predominantly near the salt lakes, while gypsum dominates in distal Gobi areas, illustrating the spatial mechanisms of the salt cycle. This study advances understanding of salinity cycling mechanisms in arid regions and provides a scientific basis for the sustainable exploitation of salt lake resources and the development of targeted ecological restoration strategies.