Soil organic matter components and sesquioxides integrally regulate aggregate stability and size distribution under erosion and deposition conditions in southern China
Geng Guo , Yu Kong , Yanyin Xu , Xiaoying Peng , Manting Niu , Guangruo Zeng , Zhen Ouyang , Jun Liu , Chen Zhang , Jie Lin
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引用次数: 0
Abstract
Water erosion considerably affects the stability and particle size distribution of soil aggregates, but the underlying mechanisms of water erosion remain unclear. To this end, we selected four landscape positions (top-, up-, mid-, and toe-slope) with distinct erosion and deposition characteristics on a typical eroded slope in southern China to conduct experiments- aiming to investigate the main drivers of soil aggregate stability during erosion and deposition processes. Soil samples were collected from 12 sites, and 4 size classes (>2, 2–0.25, 0.25–0.053, and <0.053 mm) of soil aggregates were obtained using the wet sieving method. The composition and stability of the soil aggregates, as well as the contents of organic (organic matter components) and inorganic (iron-aluminum oxides) cementing materials of different particle sizes, were determined. The results indicated that erosion significantly reduced the aggregate stability and the >0.25 mm water-stable aggregate content (WR0.25) (P < 0.05). The mean weight diameter (MWD) and geometric mean diameter (GMD) values of the soil aggregates at the eroding site decreased, and the fractal dimension (FD) increased. Furthermore, erosion markedly reduced the humic acid (HA) and fulvic acid (FA) contents in the bulk soils and soil aggregates, while the HA content showed no obvious difference between the eroding and depositional sites. In addition to the presence of complexed iron/alumina oxides (Fep/Alp), erosion markedly reduced the contents of amorphous (Feo/Alo) and free-form (Fed/Ald) iron/alumina oxides in the bulk soils and size fractions. Moreover, Fed/Ald, Fep and Feo/Alo were present in the microaggregates, while Alp was found in the macroaggregates. Additionally, boosted regression tree (BRT) analysis indicated that FA (36.70 %), Feo (19.00 %), and Ald (12.71 %) were the crucial predictors of soil aggregate stability. These findings further confirm that the organic and inorganic cementing materials in red soils collectively contribute to aggregate stabilization under the impact of erosion. This study facilitates a deeper understanding of the mechanisms governing soil aggregate stability in eroded landscapes, and provides a theoretical basis for biogeochemical cycling processes.
期刊介绍:
The Journal of Hydrology publishes original research papers and comprehensive reviews in all the subfields of the hydrological sciences including water based management and policy issues that impact on economics and society. These comprise, but are not limited to the physical, chemical, biogeochemical, stochastic and systems aspects of surface and groundwater hydrology, hydrometeorology and hydrogeology. Relevant topics incorporating the insights and methodologies of disciplines such as climatology, water resource systems, hydraulics, agrohydrology, geomorphology, soil science, instrumentation and remote sensing, civil and environmental engineering are included. Social science perspectives on hydrological problems such as resource and ecological economics, environmental sociology, psychology and behavioural science, management and policy analysis are also invited. Multi-and interdisciplinary analyses of hydrological problems are within scope. The science published in the Journal of Hydrology is relevant to catchment scales rather than exclusively to a local scale or site.