Rivers across the Siberian Arctic unearth the patterns of carbon release from thawing permafrost

Wild, B.; Andersson, A.; Bröder, L.; Vonk, J.; Hugelius, G.; McClelland, J.W.; Song, W.; Raymond, P.A.; Gustafsson, Ö.
2019 | Proc. Natl. Acad. Sci. U.S.A. | 116 (21) (10280-10285)

Distribution of Fe isotopes in particles and colloids in the salinity gradient along the Lena River plume, Laptev Sea

Sarah Conrad; Johan Ingri; Johan Gelting; Fredrik Nordblad; Emma Engström; Ilia Rodushkin; Per S. Andersson; Don Porcelli; Örjan Gustafsson; Igor Semiletov; Björn Öhlander
2019 | Biogeosciences | 16 (1305-1319)

Source apportionment of circum-Arctic atmospheric black carbon from isotopes and modeling

P. Winiger; T. E. Barrett; R. J. Sheesley; L. Huang; S. Sharma; L. A. Barrie; K. E. Yttri; N. Evangeliou; S. Eckhardt; A. Stohl; Z. Klimont; C. Heyes; I. P. Semiletov; O. V. Dudarev; A. Charkin; N. Shakhova; H. Holmstrand; A. Andersson; Ö. Gustafsson
2019 | Sci. Adv. | 5 (2)

Photochemical degradation affects the light absorption of water-soluble brown carbon in the South Asian outflow

Sanjeev Dasari; August Andersson; Srinivas Bikkina; Henry Holmstrand; Krishnakant Budhavant; Sreedharan Satheesh; Eija Asmi; Jutta Kesti; John Backman; Abdus Salam; Deewan Singh Bisht; Suresh Tiwari; Zahid Hameed; Örjan Gustafsson;
2019 | Sci. Adv. | 5, no. 1, eaau8066
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Light-absorbing organic aerosols, known as brown carbon (BrC), counteract the overall cooling effect of aerosols on Earth’s climate. The spatial and temporal dynamics of their light-absorbing properties are poorly constrained and unaccounted for in climate models, because of limited ambient observations. We combine carbon isotope forensics (δ13C) with measurements of light absorption in a conceptual aging model to constrain the loss of light absorptivity (i.e., bleaching) of water-soluble BrC (WS-BrC) aerosols in one of the world’s largest BrC emission regions—South Asia. On this regional scale, we find that atmospheric photochemical oxidation reduces the light absorption of WS-BrC by ~84% during transport over 6000 km in the Indo-Gangetic Plain, with an ambient first-order bleaching rate of 0.20 ± 0.05 day−1 during over-ocean transit across Bay of Bengal to an Indian Ocean receptor site. This study facilitates dynamic parameterization of WS-BrC absorption properties, thereby constraining BrC climate impact over South Asia.

Quantifying degradative loss of terrigenous organic carbon in surface sediments across the Laptev and East Siberian Sea

Lisa Bröder; August Andersson; Tommaso Tesi; Igor Semiletov; Örjan Gustafsson
2019 | Global Biogeochem Cycles | 33 (85-99)

Remobilization of old permafrost carbon to Chukchi Sea sediments during the end of the last deglaciation

Jannik Martens; Birgit Wild; Christof Pearce; Tommaso Tesi; August Andersson; Lisa Bröder; Matt O'Regan; Martin Jakobsson; Martin Sköld; Laura Gemery; Thomas M. Cronin; Igor Semiletov; Oleg V. Dudarev; Örjan Gustafsson
2019 | Global Biogeochem Cycles | 33

Climate warming is expected to destabilize permafrost carbon (PF‐C) by thaw‐erosion and deepening of the seasonally thawed active layer and thereby promote PF‐C mineralization to CO2 and CH4. A similar PF‐C remobilization might have contributed to the increase in atmospheric CO2 during deglacial warming after the last glacial maximum. Using carbon isotopes and terrestrial biomarkers (Δ14C, δ13C, and lignin phenols), this study quantifies deposition of terrestrial carbon originating from permafrost in sediments from the Chukchi Sea (core SWERUS‐L2‐4‐PC1). The sediment core reconstructs remobilization of permafrost carbon during the late Allerød warm period starting at 13,000 cal years before present (BP), the Younger Dryas, and the early Holocene warming until 11,000 cal years BP and compares this period with the late Holocene, from 3,650 years BP until present. Dual‐carbon‐isotope‐based source apportionment demonstrates that Ice Complex Deposit—ice‐ and carbon‐rich permafrost from the late Pleistocene (also referred to as Yedoma)—was the dominant source of organic carbon (66 ± 8%; mean ± standard deviation) to sediments during the end of the deglaciation, with fluxes more than twice as high (8.0 ± 4.6 g·m−2·year−1) as in the late Holocene (3.1 ± 1.0 g·m−2·year−1). These results are consistent with late deglacial PF‐C remobilization observed in a Laptev Sea record, yet in contrast with PF‐C sources, which at that location were dominated by active layer material from the Lena River watershed. Release of dormant PF‐C from erosion of coastal permafrost during the end of the last deglaciation indicates vulnerability of Ice Complex Deposit in response to future warming and sea level changes.

Carbonaceous material export from Siberian permafrost tracked across the Arctic Shelf using Raman spectroscopy

Robert B. Sparkes; Melissa Maher; Jerome Blewett; Ayça Doğrul Selver; Örjan Gustafsson; Igor P. Semiletov; Bart E. van Dongen
2018 | TC | 12 (3293-3309)

Dissolved organic matter and its optical characteristics in the Laptev and East Siberian seas: spatial distribution and interannual variability (2003-2011)

Pugach, SP; Pipko, II; Shakhova, NE; Shirshin, EA; Perminova, IV; Gustafsson, O; Bondur, VG; Ruban, AS; Semiletov, IP
2018 | Ocean Sci. | 14 (1) (87-103)
arctic shelf waters , carbonate system , co2 fluxes , coastal , dynamics , lena river , ocean , parameters , permafrost-carbon , subsea permafrost
The East Siberian Arctic Shelf (ESAS) is the broadest and shallowest continental shelf in the world. It is characterized by both the highest rate of coastal erosion in the world and a large riverine input of terrigenous dissolved organic matter (DOM). DOM plays a significant role in marine aquatic ecosystems. The chromophoric fraction of DOM (CDOM) directly affects the quantity and spectral quality of available light, thereby impacting both primary production and ultraviolet (UV) exposure in aquatic ecosystems. A multiyear study of CDOM absorption, fluorescence, and spectral characteristics was carried out over the vast ESAS in the summer-fall seasons. The paper describes observations accomplished at 286 stations and 1766 in situ high-resolution optical measurements distributed along the nearshore zone. Spatial and interannual CDOM dynamics over the ESAS were investigated, and driving factors were identified. It was shown that the atmospheric circulation regime is the dominant factor controlling CDOM distribution on the ESAS. This paper explores the possibility of using CDOM and its spectral parameters to identify the different biogeochemical regimes in the surveyed area. The analysis of CDOM spectral characteristics showed that the major part of the Laptev and East Siberian seas shelf is influenced by terrigenous DOM carried in riverine discharge. Western and eastern provinces of the ESAS with distinctly different DOM optical properties were also identified; a transition between the two provinces at around 165-170 degrees E, also consistent with hydrological and hydrochemical data, is shown. In the western ESAS, a region of substantial river impact, the content of aromatic carbon within DOM remains almost constant. In the eastern ESAS, a gradual decrease in aromaticity percentage was observed, indicating contribution of Pacific-origin waters, where allochthonous DOM with predominantly aliphatic character and much smaller absorption capacity predominates. In addition, we found a stable tendency towards reduced concentrations of CDOM and dissolved lignin and an increase in spectral slope and slope ratio values eastward from the Lena River delta; the Lena is the main supplier of DOM to the eastern Arctic shelf. The strong positive correlation (r = 0.97) between dissolved organic carbon (DOC) and CDOM values in the surface shelf waters influenced by terrigenous discharge indicates that it is feasible to estimate DOC content from CDOM fluorescence assessed in situ using a WETStar fluorometer. This approach is reliable over the salinity range of 3 to 24.5. The fact that there is little difference between predicted and observed parameters indicates that the approach is justified. The direct estimation of DOM optical characteristics in the surface ESAS waters provided by this multiyear study will also be useful for validating and calibrating remote sensing data.

Release of black carbon from thawing permafrost estimated by sequestration fluxes in the East Siberian Arctic Shelf recipient

Salvadó, J.A.; Bröder, L.; Andersson, A.; Semiletov, I.P; Gustafsson, Ö.
2017 | Global Biogeochem Cycles | 31 (10) (1501-1515)

Discovery and characterization of submarine groundwater discharge in the Siberian Arctic seas: a case study in the Buor-Khaya Gulf, Laptev Sea

Alexander N. Charkin.; Michiel Rutgers van der Loeff; Natalia E. Shakhova; Örjan Gustafsson; Oleg V. Dudarev; Maxim S. Cherepnev; Anatoly N. Salyuk; Andrey V. Koshurnikov; Eduard A. Spivak; Alexey Y. Gunar; Alexey S. Ruban; Igor P. Semiletov
2017 | TC | 11 (2305-2327)

Sources and characteristics of terrestrial carbon in Holocene-scale sediments of the East Siberian Sea

Kirsi Keskitalo; Tommaso Tesi; Lisa Bröder; August Andersson; Christof Pearce; Martin Sköld; Igor P. Semiletov; Oleg V. Dudarev; Örjan Gustafsson
2017 | J Clim | 13 (1213-1226)

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