Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
8893812 | Geoderma | 2019 | 12 Pages |
Abstract
The chemical characteristics of dissolved organic matter (DOM) in soils that experience erosion and deposition are key to the biogeochemical cycle of carbon on the earth's surface. However, data related to the transport and fate of DOM from soils that experience erosion and different management practices are scarce, particularly at catchment scales. In this study, soil samples (uppermost 10â¯cm) were collected from uplands representing four land use types (cropland, fallow, grassland, and forests) as well as gullies, and sediment samples (100â¯cm sampled at 10 depths) were collected from sediments retained by a check dam. Chemical characteristics of DOM in soils and sediments, as well as subsequent source identification, were inferred from UV-Visible absorption and fluorescence excitation emission matrix (EEM)-parallel factor analysis (PARAFAC) as well as principal component analysis (PCA). The results indicated higher aromaticity, hydrophobic fraction, and molecular size in DOM from forest soils than those from other land use types and gullies. These factors were also higher in soils at the eroding sites than in sediments. EEM-PARAFAC analysis demonstrated that more protein-like components (tyrosine-like and tryptophan-like combined, accounting for >42.77%) were present in sediments compared to soils with terrestrial humic-like substances. PCA results revealed that approximately 72% of the variance in the DOM characteristics was explained by the first two principal components and that the DOM in upland and gully soils had a negligible contribution to DOM in sediments. Combined our results indicate that, despite the large amount of sediment-associated carbon that is transported by erosion and trapped in check dams, DOM is likely mineralized during soil transport. Furthermore, biological production of new organic compounds (autochthonous sources) are likely the major source of sediment DOM in depositional settings.
Related Topics
Physical Sciences and Engineering
Earth and Planetary Sciences
Earth-Surface Processes
Authors
Chun Liu, Zhongwu Li, Asmeret Asefaw Berhe, Haibing Xiao, Lin Liu, Danyang Wang, Hao Peng, Guangming Zeng,