Chronology and Environmental Responses of Nebkhas in the Aibi Lake Basin, Central Asia

Central Asia is a typical arid region where surface water resources are scarce and primarily sustained by westerly precipitation and glacier meltwater. Lakes and their drainage basins therefore play a critical role in sustaining fragile oasis ecosystems, and their responses to climatic variability and human activities provide key insights into regional environmental change. Aibi Lake, a representative terminal lake in arid Central Asia, is surrounded by abundant nebkhas developed on the dried lakebed. These landforms reflect the coupled vegetation-aeolian processes. However, their formation and evolution remain poorly constrained due to limited high-precision chronology. Here we establish a robust chronology for nebkha development in the southeastern Aibi Lake basin by integrating single-grain K-feldspar pIR50IR150 dating with Cs-137 measurements, and reconstruct environmental changes using grain-size distributions and magnetic susceptibility. Internal checks indicate that the single-grain pIR50IR150 protocol is suitable for dating young nebkha sediments. Cs-137 is mainly concentrated in the upper ~30 cm, within which two fallout horizons (1963 and 1986) are identified despite the relatively coarse sampling resolution in the uppermost section. The K-feldspar pIR50IR150 age at ~30 cm agrees with the independent Cs-137 constraint, further supporting the reliability of the established chronology. The combined age control indicates that the main nebkha body accumulated over the past ~200 years, whereas the underlying deposits likely reflect erosion and reworking of inter-nebkha surfaces during nebkha development. The recent nebkha formation initiated around ~200 years ago, followed by slow accretion under weak aeolian conditions, rapid growth since the mid-20th century driven by intensified aridification and accelerated lake shrinkage, and a recent decline in sediment accumulation associated with surface stabilization. These results demonstrate that young Nitraria nebkhas can serve as sensitive archives for reconstructing recent aeolian activity and environmental change at decadal-to-centennial timescales in arid terminal lake basins.