Abrupt permafrost collapse enhances organic carbon, CO 2 , nutrient and metal release into surface waters

Loiko, Sergey V.; Pokrovsky, Oleg S.; Raudina, Tatiana V.; Lim, Artem G.; Kolesnichenko, Larisa G.; Shirokova, Liudmila S.; Vorobyev, Sergey N.; Kirpotin, Sergey N.

doi:10.1016/j.chemgeo.2017.10.002

Cited by 65 publications

(48 citation statements)

References 76 publications

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“…Indeed, the highly positive impact of the forest coverage of the watershed on nutrient (PO 4 , Si, P tot , K, Mn), CO 2 , DIC, and Ca concentrations in the permafrost-bearing zone may be due to feeding the rivers by shallow subsurface waters. These waters are present only in forested zones, typically along the river valley, where the permafrost is absent or its thickness is particularly low [40,47,54,55]. In such settings, the groundwaters that feed the river interact with mineral horizons and can be enriched in "mineral" nutrients such as P, Si, and K, whereas Mn may be mobilized in reduced form from Mn hydroxide nodules, abundant at the base of the sand horizon [48,56].…”

Section: Discussionmentioning

confidence: 99%

Permafrost Boundary Shift in Western Siberia May Not Modify Dissolved Nutrient Concentrations in Rivers

Vorobyev

Pokrovsky

Serikova

et al. 2017

Water

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Section: Discussionmentioning

confidence: 99%

Permafrost Boundary Shift in Western Siberia May Not Modify Dissolved Nutrient Concentrations in Rivers

Vorobyev

Pokrovsky

Serikova

et al. 2017

Water

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“…High-latitude rivers are most vulnerable to ongoing climate change via altering their hydrological regime (Bring et al, 2016) and widespread permafrost thaw that stimulates nutrient release (Vonk et al, 2015). For carbon (C), the particulate fraction (POC) contributes substantially to the total organic C export from the continent to the ocean (Schlesinger and Melack, 1981;Lal, 2003;Ludwig and Probst, 1996;Galy et al, 2015;Li et al, 2017;Coppola et al, 2018); a 2-fold increase of Arctic rivers POC fluxes by 2100 is predicted (Gordeev and Kravchishina, 2009). Although the reasons for strong variations of POC in freshwater are not yet fully understood (Tian et al, 2015;Lee et al, 2016;Yang et al, I. V. Krickov et al: Riverine particulate C and N across permafrost gradient 2016), the temperature (Hilton, 2017) and runoff (Goñi et al, 2013) combined with local storm events (Jeong et al, 2012;Wiegner et al, 2009) are widely recognized as the most important driving factors.…”

Section: Introductionmentioning

confidence: 99%

Riverine particulate C and N generated at the permafrost thaw front: case study of western Siberian rivers across a 1700 km latitudinal transect

et al. 2018

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Abstract. In contrast to numerous studies on the dynamics of dissolved (<0.45 µm) elements in permafrost-affected high-latitude rivers, very little is known of the behavior of river suspended (>0.45 µm) matter (RSM) in these regions. In order to test the effect of climate, permafrost and physio-geographical landscape parameters (bogs, forest and lake coverage of the watershed) on RSM and particulate C, N and P concentrations in river water, we sampled 33 small and medium-sized rivers (10–100 000 km2 watershed) along a 1700 km N–S transect including both permafrost-affected and permafrost-free zones of the Western Siberian Lowland (WSL). The concentrations of C and N in RSM decreased with the increase in river watershed size, illustrating (i) the importance of organic debris in small rivers which drain peatlands and (ii) the role of mineral matter from bank abrasion in larger rivers. The presence of lakes in the watershed increased C and N but decreased P concentrations in the RSM. The C:N ratio in the RSM reflected the source from the deep soil horizon rather than surface soil horizon, similar to that of other Arctic rivers. This suggests the export of peat and mineral particles through suprapermafrost flow occurring at the base of the active layer. There was a maximum of both particulate C and N concentrations and export fluxes at the beginning of permafrost appearance, in the sporadic and discontinuous zone (62–64∘ N). This presumably reflected the organic matter mobilization from newly thawed organic horizons in soils at the active latitudinal thawing front. The results suggest that a northward shift of permafrost boundaries and an increase in active layer thickness may increase particulate C and N export by WSL rivers to the Arctic Ocean by a factor of 2, while P export may remain unchanged. In contrast, within a long-term climate warming scenario, the disappearance of permafrost in the north, the drainage of lakes and transformation of bogs to forest may decrease C and N concentrations in RSM by 2 to 3 times.

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“…There is increasing evidence showing permafrost degradation (including permafrost erosion and thawing) occurring in the northern high‐latitude regions (Douglas et al, ; Jorgenson et al, ; Lawrence et al, ; Ping et al, ). In addition to vertical losses of CO 2 and CH 4 from the soil zone to atmosphere (Davidson & Janssens, ; Schuur et al, ), mobilization of SOC and/or the lateral transport of DOC (dissolved organic carbon) and POC (particulate organic carbon, including those in sediments) from permafrost into the aquatic zone have received increasing attention (Dean et al, ; Guo et al, ; Hayes et al, ; Loiko et al, ; Mann et al, ; McGuire et al, ; Neff et al, ; Ping et al, ; Vonk et al, ). Thus, permafrost thaw and subsequent SOC release into aquatic environments or atmosphere have the potential to be a strong positive feedback to climate warming (Hayes et al, ; Schuur et al, ; Vonk & Gustafsson, ).…”

Section: Introductionmentioning

confidence: 99%

“…Thus, permafrost thaw and subsequent SOC release into aquatic environments or atmosphere have the potential to be a strong positive feedback to climate warming (Hayes et al, ; Schuur et al, ; Vonk & Gustafsson, ). Recent Arctic warming has also resulted in significant increase in freshwater discharge (McClelland et al, ) and likely the concentrations and fluxes of nutrients and organic matter from Arctic rivers to the Arctic Ocean (Guo et al, ; Holmes et al, ; Loiko et al, ; McClelland et al, ; Neff et al, ).…”

Section: Introductionmentioning

confidence: 99%

Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska

2018

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Soil organic matter (SOM) in northern high-latitude regions is a major component of the global carbon cycle. However, the yield of soil-dissolved organic matter (DOM) during soil-water interactions and its chemical characteristics and reactivities remain poorly understood. We report here elemental composition and isotopic signatures of bulk-SOM from northern Alaska, and yields of water-leachable soil-DOM, including dissolved organic carbon, dissolved organic nitrogen, and dissolved organic phosphorus, and nutrients (dissolved inorganic nitrogen and phosphate). The bulk-SOM contained 5,400-373,900 μg-C/g-soil, 500-12,610 μg-N/g-soil, and 38.6-384 μg-P/g-soil, with a C/N ratio of 13-37 and a C/P ratio of 80-3,911. The water-extractable dissolved organic carbon, dissolved organic nitrogen, and dissolved organic phosphorus only accounted for 0.58-2.5%, 0.91-3.4%, and 1.2-3.0% of their corresponding total soil-OC, N, and OP, respectively. While SOM-δ 13 C was less variable (À27.08‰ to À26.49‰) showing the same overall C source, 14 C-ages varied widely from 1,170 ± 20 to 16,200 ± 55 years before present, indicating different deposition-conditions and subsequent-processes among the soil samples. The specific-UV-absorbance at 254 nm (or aromaticity) of soil-DOM differed considerably and was negatively correlated to spectral slope values. A humic-like (C1), a low-molecular-weight fulvic-like (C2), and a protein-like component (C3) were identified as the major fluorescent-DOM components. The C3/C2 and C3/C1 ratios generally increased with SOM-14 C-age, suggesting a preferential degradation/transformation of humic-like and fulvic-like components or a transformation/production of protein-like components within permafrost. Both biological and humification indices increased with 14 C-age, excluding the oldest soil, which pointed to a preferential preservation or transformation/production of protein-like DOM within permafrost, implying that soil-DOM derived from old permafrost can be highly vulnerable and readily decomposed upon permafrost thaw.Plain Language Summary The yields of soil dissolved organic matter (DOM) and nutrients (N and P) from different aged soils in northern Alaska were quantified in the laboratory mimicking soil-water interactions upon permafrost thaw. The overall fluxes of soil-DOM and nutrients can significantly influence carbon and nutrient cycle and the ecosystem as a whole in Arctic waterways and coastal environment although the yields were generally within 4% of their corresponding total mass in the bulk soil. Humic-like substances with high optical reactivity were the major organic components preserved in permafrost, but the relative percentage of protein-like components having high biological activity increased with increasing soil C-14 age. This implies that soil-DOM released from old-permafrost thaw can be highly vulnerable and readily decomposed, causing a positive feedback to climate change.

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Abrupt permafrost collapse enhances organic carbon, CO 2 , nutrient and metal release into surface waters

Cited by 65 publications

References 76 publications

Permafrost Boundary Shift in Western Siberia May Not Modify Dissolved Nutrient Concentrations in Rivers

Permafrost Boundary Shift in Western Siberia May Not Modify Dissolved Nutrient Concentrations in Rivers

Riverine particulate C and N generated at the permafrost thaw front: case study of western Siberian rivers across a 1700 km latitudinal transect

Yields and Characterization of Dissolved Organic Matter From Different Aged Soils in Northern Alaska

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