Detecting the signature of permafrost thaw in Arctic rivers

Spencer, Robert G. M.; Mann, P.; Dittmar, Thorsten; Eglinton, T. I.; McIntyre, Cameron; Holmes, Robert M.; Zimov, N.; Stubbins, Aron

doi:10.1002/2015gl063498

Cited by 311 publications

(473 citation statements)

References 28 publications

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“…Most of this biologically transformed ancient OM is converted to CO 2 rather than assimilated and moved up trophic levels (Dittmar and Kattner, 2003). The breakdown of old OM is particularly relevant in the Arctic, where warming is expected to thaw permafrost and push the boundary for regions where permafrost can exist to higher latitudes, releasing large amounts of ancient OM into rivers (Guo et al, 2004;Hood et al, 2009;Hessen et al, 2010;Spencer et al, 2015).…”

Section: Conversion Of Om To Co 2 In Inland Watersmentioning

confidence: 99%

Where Carbon Goes When Water Flows: Carbon Cycling across the Aquatic Continuum

et al. 2017

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The purpose of this review is to highlight progress in unraveling carbon cycling dynamics across the continuum of landscapes, inland waters, coastal oceans, and the atmosphere. Earth systems are intimately interconnected, yet most biogeochemical studies focus on specific components in isolation. The movement of water drives the carbon cycle, and, as such, inland waters provide a critical intersection between terrestrial and marine biospheres. Inland, estuarine, and coastal waters are well studied in regions near centers of human population in the Northern hemisphere. However, many of the world's large river systems and their marine receiving waters remain poorly characterized, particularly in the tropics, which contribute to a disproportionately large fraction of the transformation of terrestrial organic matter to carbon dioxide, and the Arctic, where positive feedback mechanisms are likely to amplify global climate change. There are large gaps in current coverage of environmental observations along the aquatic continuum. For example, tidally-influenced reaches of major rivers and near-shore coastal regions around river plumes are often left out of carbon budgets due to a combination of methodological constraints and poor data coverage. We suggest that closing these gaps could potentially alter global estimates of CO 2 outgassing from surface waters to the atmosphere by several-fold. Finally, in order to identify and constrain/embrace uncertainties in global carbon budget estimations it is important that we further adopt statistical and modeling approaches that have become well-established in the fields of oceanography and paleoclimatology, for example.

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Section: Conversion Of Om To Co 2 In Inland Watersmentioning

confidence: 99%

Where Carbon Goes When Water Flows: Carbon Cycling across the Aquatic Continuum

et al. 2017

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“…The significant amount of DOC in the Arctic Ocean mainly originates from riverine inflow and permafrost thaw Amon et al, 2012;Spencer et al, 2015). The riverine input can be monitored by optical methods with absorption, fluorescence, or remote-sensing measurements (Spencer et al, 2012;Walker et al, 2013;Fichot et al, 2013;Mann et al, 2016).…”

Section: Relationship Between Cdom Absorption and Docmentioning

confidence: 99%

Characteristics of chromophoric and fluorescent dissolved organic matter in the Nordic Seas

et al. 2018

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Abstract. Optical properties of chromophoric (CDOM) and fluorescent dissolved organic matter (FDOM) were characterized in the Nordic Seas including the West Spitsbergen Shelf during June-July 2013, 2014, and 2015. The CDOM absorption coefficient at 350 nm, a CDOM (350) showed significant interannual variation (T test, p < 0.00001). In 2013, the highest average a CDOM (350) values (a CDOM (350) = 0.30 ± 0.12 m −1 ) were observed due to the influence of cold and low-salinity water from the Sørkapp Current (SC) in the southern part of the West Spitsbergen Shelf. In 2014, a CDOM (350) values were significantly lower (T test, p < 0.00001) than in 2013 (average a CDOM (350) = 0.14 ± 0.06 m −1 ), which was associated with the dominance of warm and saline Atlantic Water (AW) in the region, while in 2015 intermediate CDOM absorption (average a CDOM (350) = 0.19 ± 0.05 m −1 ) was observed. In situ measurements of three FDOM components revealed that fluorescence intensity of protein-like FDOM dominated in the surface layer of the Nordic Seas. Concentrations of marine and terrestrial humic-like DOM were very low and distribution of those components was generally vertically homogenous in the upper ocean (0-100 m). Fluorescence of terrestrial and marine humic-like DOM decreased in surface waters (0-15 m) near the sea ice edge due to dilution of oceanic waters by sea ice meltwater. The vertical distribution of protein-like FDOM was characterized by a prominent subsurface maximum that matched the subsurface chlorophyll a maximum and was observed across the study area. The highest protein-like FDOM fluorescence was observed in the Norwegian Sea in the core of warm AW. There was a significant relationship between the proteinlike fluorescence and chlorophyll a fluorescence (R 2 = 0.65, p < 0.0001, n = 24 490), which suggests that phytoplankton was the primary source of protein-like DOM in the Nordic Seas and West Spitsbergen Shelf waters. Observed variability in selected spectral indices (spectral slope coefficient, S 300-600 , carbon-specific CDOM absorption coefficient at 254 and 350 nm, SUVA 254 , a * CDOM (350)) and the nonlinear relationship between CDOM absorption and the spectral slope coefficient also indicate a dominant marine (autochthonous) source of CDOM and FDOM in the study area. Further, our data suggest that a CDOM (350) cannot be used to predict dissolved organic carbon (DOC) concentrations in the study region; however the slope coefficient (S 300-600 ) shows some promise in being used.

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“…In contrast, hydrophilic fatty microbial products with low molecular weights were desorbed and released (Striegl et al, 2005). To date, a partial theoretical framework and methods have been developed to understand alterations in DOC chemical characteristics following permafrost degradation (Spencer et al, 2015). But uncertainties still exist in understanding the entire way hydrological processes affect the magnitude and chemical characteristics of DOC exported from permafrost peatland catchments.…”

Section: Introductionmentioning

confidence: 99%

Hydrological processes and permafrost regulate magnitude, source and chemical characteristics of dissolved organic carbon export in a peatland catchment of northeastern China

Guo

Song

Tan

et al. 2018

Hydrol. Earth Syst. Sci.

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Abstract. Permafrost thawing in peatlands has the potential to alter the catchment export of dissolved organic carbon (DOC), thus influencing the carbon balance and cycling in linked aquatic and ocean ecosystems. Peatlands along the southern margins of the Eurasian permafrost are relatively underexplored despite the considerable risks associated with permafrost degradation due to climate warming. This study examined dynamics of DOC export from a permafrost peatland catchment located in northeastern China during the 2012 to 2014 growing seasons. The estimated annual DOC loads varied greatly between 3211 and 19 022 kg yr −1 , with a mean DOC yield of 4.7 g m −2 yr −1 . Although the estimated DOC yield was in the lower range compared with other permafrost regions, it was still significant for the net carbon balance in the studied catchment. There were strong linkages between daily discharge and DOC concentrations in both wet and dry years, suggesting a transport-limited process of DOC delivery from the catchment. Discharge explained the majority of both seasonal and interannual variations of DOC concentrations, which made annual discharge a good indicator of total DOC load from the catchment. As indicated by three fluorescence indices, DOC source and chemical characteristics tracked the shift of flow paths during runoff processes closely. Interactions between the flow path and DOC chemical characteristics were greatly influenced by the seasonal thawing of the soil active layer. The deepening of the active layer due to climate warming likely increases the proportion of microbial-originated DOC in baseflow discharge.

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Detecting the signature of permafrost thaw in Arctic rivers

Cited by 311 publications

References 28 publications

Where Carbon Goes When Water Flows: Carbon Cycling across the Aquatic Continuum

Where Carbon Goes When Water Flows: Carbon Cycling across the Aquatic Continuum

Characteristics of chromophoric and fluorescent dissolved organic matter in the Nordic Seas

Hydrological processes and permafrost regulate magnitude, source and chemical characteristics of dissolved organic carbon export in a peatland catchment of northeastern China

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