| Autor: |
Brosens Liesa, Campforts Benjamin, Robinet jérémy, Vanacker, Veerle, Opfergelt, Sophie, Ameijeiras Mariño, Yolanda, Minella Jean, Gerard Govers |
| Přispěvatelé: |
UCL - SST/ELI/ELIE - Environmental Sciences, UCL - SST/ELI/ELIC - Earth & Climate |
| Jazyk: |
angličtina |
| Rok vydání: |
2020 |
| Předmět: |
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| Popis: |
Soil thickness and residence time are regulated by a dynamic interplay between soil formation and lateral transport of soil particles and solutes. To unravel this interplay and infer patterns and rates of chemical weathering, soil physical and chemical properties can be used. Here, we present an integrated approach combining numerical modeling with field measurements to assess the impact of slope gradient on soil thickness and chemical weathering at a regional scale. We first perform a number of synthetic model runs simulating soil formation, weathering, erosion and deposition, which show that soil thickness and weathering degree decline with increasing slope gradient. We then evaluate how those functional relationships compare to soil-landscape data observed in the field. In a sub-tropical region in Southern Brazil, soils are sampled at 100 mid-slope positions under varying slope gradient. The weathering degree is determined by using three chemical weathering indices: ratio of iron oxides to total iron (Fed/Fet), chemical index of alteration (CIA) and total reserve in bases (TRB). By using interrelationships between slope gradient, soil thickness and weathering degree, we could calibrate an enhanced version of the Be2D model, enabling us to constrain soil residence times and chemical weathering rates. Modeled chemical weathering rates vary by two orders of magnitude depending on slope gradient and are positively related to modeled erosion rates. Soil residence times are calculated by taking into account both local soil production and material transported from upslope positions and vary between ca. 20 and 1700 kyr, with an average value of ca. 290 kyr. This shows that in a soil-mantled area a long time is required to develop a steady state soilscape. Combining a numerical soil-landscape evolution model with field data allowed us to gain insight and make inferences about the relationships between soil thickness and topography with weathering degrees and rates. Notwithstanding model limitations and data uncertainties, we demonstrate the potential of an integrated approach, where field data and numerical modeling are integrated to unravel the time scale of soil weathering along transport over hillslopes. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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