Abrupt permafrost collapse enhances organic carbon, CO 2 , nutrient and metal release into surface waters
| Autor: | A. G. Lim, Larisa G. Kolesnichenko, Oleg S. Pokrovsky, T. V. Raudina, Sergey N. Vorobyev, Sergey V. Loiko, Liudmila S. Shirokova, Sergey N. Kirpotin |
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| Rok vydání: | 2017 |
| Předmět: |
Total organic carbon
Peat 010504 meteorology & atmospheric sciences Geology Soil science 010501 environmental sciences Permafrost 01 natural sciences Geochemistry and Petrology Dissolved organic carbon Permafrost carbon cycle Palsa Thaw depth Surface water 0105 earth and related environmental sciences |
| Zdroj: | Chemical Geology. 471:153-165 |
| ISSN: | 0009-2541 |
| Popis: | Thawing of frozen peat in discontinuous permafrost zones may significantly modify the environment at local (slumps and engineering damages) and global (greenhouse gases regime) scales. We studied the aquatic geochemistry of CO2, CH4, dissolved organic carbon (DOC), P, Si, and colloidal trace metal from hollows, depressions, permafrost subsidences and soil waters in the actively thawing discontinuous permafrost zone of Western Siberia Lowland (WSL). This site of abrupt permafrost collapse is dominated by minerotrophic fens located within the flat mound peat bog. The CO2, DOC, major and trace metal concentrations decreased with the increase of the surface area of the water body, along the hydrological continuum (soil water → hollows → depressions and permafrost subsidences → thaw ponds → thermokarst lakes). Aqueous concentrations of CO2, CH4, Ca, Si, P, Al, Fe, Nd, and U were a factor of 4 to 10 higher in the site of catastrophic thaw compared to the steady thawing of a palsa peat bog that was previously studied in the same region. The colloids (1 kDa–0.45 μm) formed in hot spots were strongly enriched in Fe, Al, and trivalent and tetravalent hydrolysates relative to organic carbon. Because the increase in the thickness of the thawing depth intensifies the input of inorganic components from deep mineral horizons, abrupt permafrost thaw enriches the surface waters in Al-rich colloids and low molecular weight organic complexes. As a result, the WSL's surface water colloidal composition may shift from DOM-rich and DOM-Fe-rich to DOM-Al-rich, and the release of low-soluble trivalent and tetravalent hydrolysates from the soil to the river will increase. We hypothesize that in sites of abrupt permafrost thaw, there is direct mobilization of soil waters to a hydrological network (rivers and lakes) and there is minimal transformation by autochthonous processes, which is unlike the case of steady permafrost thawing. Therefore, the change in physical factors, such as water pathways and the water residence time, within a given elementary landscape will likely control the overall impact of on-going permafrost thaw on both the surface water chemistry and dissolved greenhouse gas pattern of the territory. For this, high-resolution ( |
| Databáze: | OpenAIRE |
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