Guoqing Li

The Wushan Loess, situated in the Yangtze Three Gorges region of China, represents the southernmost aeolian loess deposit in China and provides critical insights into Late Pleistocene paleoenvironmental conditions and East Asian monsoon dynamics. Despite its significance, the genesis and provenance of this unique loess deposit remain controversial. This study employs an integrated multi-proxy approach combining detrital zircon U-Pb geochronology, optically stimulated luminescence (OSL) dating, and detailed grain size analysis to systematically investigate the provenance and depositional mechanisms of the Wushan Loess. Three representative loess–paleosol profiles (Gaotang-GT, Badong-BD, and Zigui-ZG) were analyzed, yielding 17 OSL ages, 729 grain size measurements, and approximately 420 analyses per profile were conducted, yielding 1189 valid ages (GT 406, BD 391, ZG 402). OSL chronology constrains the deposition period to 18–103 ka (Marine Isotope Stages 2–5), coinciding with enhanced East Asian winter monsoon activity during the Last Glacial period. Grain size analysis reveals a dominant silt fraction (modal size: 20–25 μm) characteristic of aeolian transport, with coarse silt (20–63 μm) averaging 47.1% and fine silt (<20 μm) averaging 44.2% of the sediments. Detrital zircon U-Pb age spectra exhibit consistent major peaks at 200–220 Ma, 450–500 Ma, 720–780 Ma, and 1800–1850 Ma across all profiles. Kernel Density Estimation (KDE) and Multi-Dimensional Scaling (MDS) analyses indicate a mixed provenance model. Non-negative least squares (NNLS) unmixing confirms this quantitative source apportionment., dominated by proximal contributions from the upper Yangtze River basin (including the Three Gorges area and Sichuan Basin, ~65%–70%), supplemented by distal dust input from the Loess Plateau and northern Chinese deserts (~30%–35%). This study establishes for the first time a proximal-dominated provenance model for the Wushan Loess, providing new evidence for understanding southern Chinese loess formation mechanisms and Late Pleistocene East Asian monsoon evolution.

Wuhan is dotted with lakes, is known as the “City with Hundreds of Lakes”, and the development of the city is inseparable from the river and lake waters, with the evolution of the lakes affecting the construction and layout of the city. Since the 20th century, the lake evolution in the main urban area of Wuhan has been the most intense and the urban development has also been the most rapid. Therefore, on the basis of the study of the origin of different types of lakes, based on the precious high-precision historical maps of Wuhan in the early- and mid-20th century, combined with the information about lakes in Wuhan obtained from satellite remote sensing images, the evolution characteristics of the lakes in Wuhan in the past 100 years (1920~2019) were investigated through the theory of landscape fractal, and the response mechanism of lake evolution to urban expansion was further explored by being combined with the trajectory of urban expansion. The results show that the area of lakes in Wuhan declined from 2133.5 km² in 1920 to 550.8 km² in 2019, with a total decrease of 1582.7 km², an area shrinkage rate of 74.18%, and a strong amplitude of area change. The changes in the fractal dimension and the shoreline development coefficient of lakes in Wuhan city show synchronization as a whole, with occasional fluctuations, but on the whole, the fractal dimension and shoreline development coefficient of lakes are becoming smaller over a century. Specifically, the evolution of lakes in the Hankou area is mainly affected by the construction of dykes and lake filling, and most of the lakes are resolved and fragmented under the influence of urban expansion, whereas the evolution of lakes in Wuchang and Hanyang is mainly caused by the urban construction around the lakes, and many lake branches have been cut for various urban constructions, and the shape of the lake tends to be simple and regular under the influence of urban expansion. This study is of great significance for filling in the history of lake evolution in Wuhan before the popularization of remote sensing, and for guiding the rational development of lakes in Wuhan and the sustainable and healthy development of Wuhan.

Wuhan is dotted with lakes, known as “ City with Hundreds of Lakes”, the development of the city is inseparable from the river and lake waters, the evolution of the lakes has been affecting the construction and layout of the city. Since the 20th century, the lake evolution in the main urban area of Wuhan is the most intense and the urban development is also the most rapid. Therefore, based on the precious high-precision historical maps of Wuhan in the early and mid-20th century, combined with the information of lakes in Wuhan obtained from satellite remote sensing images, the evolution characteristics of lakes in Wuhan in the past 100 years (1920~2019) were investigated through the theory of landscape fractal, and the response mechanism of lake evolution to urban expansion was further explored by combining with the trajectory of urban expansion. The results show that the area of lakes in Wuhan declined from 2,133.5 km² in 1920 to 550.8 km² in 2019, with a total decrease of 1,582.7 km², an area shrinkage rate of 74.18 % , and a strong amplitude of area change. The changes of fractal dimension and shoreline development coefficient of lakes in Wuhan city show synchronization as a whole, with occasional fluctuations, but on the whole the fractal dimension and shoreline development coefficient of lakes are getting smaller in a century. Specifically, the evolution of lakes in the Hankou area is mainly affected by the construction of dykes and lake filling, and most of the lakes are resolved and fragmented under the influence of urban expansion, whereas the evolution of lakes in Wuchang and Hanyang is mainly caused by the urban construction around the lakes, and many lake branches are cut for various urban constructions, and the shape of the lake tends to be simple and regular under the influence of urban expansion. This study is of great significance to fill in the history of lake evolution in Wuhan before the popularization of remote sensing, and to guide the rational development of lakes in Wuhan and the sustainable and healthy development of Wuhan.