Climate Change Impacts on the Hydrology and Biogeochemistry of Arctic Rivers

Holmes, Robert M.; Coe, Michael T.; Fiske, Greg; Gurtovaya, Tatiana Yu.; McClelland, J. W.; Shiklomanov, A. I.; Spencer, Robert G. M.; Tank, Suzanne E.; Zhulidov, Alexander V.

doi:10.1002/9781118470596.ch1

Cited by 89 publications

(101 citation statements)

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“…The Northern Dvina watershed encompasses approximately 357,000 km 2 of predominantly low relief peatlands, not underlain by permafrost (Holmes et al, ), in Northwestern Russia draining to the White Sea (Figure ). The Northern Dvina was sampled in Arkhangelsk, Russia about 35 km from the White Sea, upstream of the river delta.…”

Section: Methodsmentioning

confidence: 99%

“…Finally, we derive new estimates for DOC and lignin phenol fluxes from the pan‐Arctic utilizing the Northern Dvina as a model river for the pan‐Arctic watershed not encompassed by the six major Arctic rivers. As a medium‐sized and northern high‐latitude constrained river the Northern Dvina is more representative of the 33% of the pan‐Arctic watershed not encapsulated by the major six Arctic watersheds (Holmes et al, ). Taking these new estimates for DOC and lignin phenols derived from incorporating the Northern Dvina, we discuss the ramifications for the fate of terrestrial‐derived DOM in the Arctic Ocean.…”

Section: Introductionmentioning

confidence: 99%

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Flux and Seasonality of Dissolved Organic Matter From the Northern Dvina (Severnaya Dvina) River, Russia

et al. 2018

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Pan‐Arctic riverine dissolved organic carbon (DOC) fluxes represent a major transfer of carbon from land‐to‐ocean, and past scaling estimates have been predominantly derived from the six major Arctic rivers. However, smaller watersheds are constrained to northern high‐latitude regions and, particularly with respect to the Eurasian Arctic, have received little attention. In this study, we evaluated the concentration of DOC and composition of dissolved organic matter (DOM) via optical parameters, biomarkers (lignin phenols), and ultrahigh resolution mass spectrometry in the Northern Dvina River (a midsized high‐latitude constrained river). Elevated DOC, lignin concentrations, and aromatic DOM indicators were observed throughout the year in comparison to the major Arctic rivers with seasonality exhibiting a clear spring freshet and also some years a secondary pulse in the autumn concurrent with the onset of freezing. Chromophoric DOM absorbance at a350 was strongly correlated to DOC and lignin across the hydrograph; however, the relationships did not fit previous models derived from the six major Arctic rivers. Updated DOC and lignin fluxes were derived for the pan‐Arctic watershed by scaling from the Northern Dvina resulting in increased DOC and lignin fluxes (50 Tg yr−1 and 216 Gg yr−1, respectively) compared to past estimates. This leads to a reduction in the residence time for terrestrial carbon in the Arctic Ocean (0.5 to 1.8 years). These findings suggest that constrained northern high‐latitude rivers are underrepresented in models of fluxes based from the six largest Arctic rivers with important ramifications for the export and fate of terrestrial carbon in the Arctic Ocean.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Flux and Seasonality of Dissolved Organic Matter From the Northern Dvina (Severnaya Dvina) River, Russia

et al. 2018

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“…Nearly half of the catchment is underlain by permafrost (16% continuous, 29% discontinuous; Holmes et al, 2013). As the Great Slave Lake serves as a very efficient sediment trap, most of the sediment delivered to the delta in fact originates from the area north of this lake.…”

Section: Study Sitementioning

confidence: 99%

Arctic Deltaic Lake Sediments As Recorders of Fluvial Organic Matter Deposition

et al. 2016

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Arctic deltas are dynamic and vulnerable regions that play a key role in land-ocean interactions and the global carbon cycle. Delta lakes may provide valuable historical records of the quality and quantity of fluvial fluxes, parameters that are challenging to investigate in these remote regions. Here we study lakes from across the Mackenzie Delta, Arctic Canada, that receive fluvial sediments from the Mackenzie River when spring flood water levels rise above natural levees. We compare downcore lake sediments with suspended sediments collected during the spring flood, using bulk (% organic carbon, % total nitrogen, 13 δ C, 14 C) and molecular organic geochemistry (lignin, leaf waxes). High-resolution age models ( 137 Cs, 210 Pb) of downcore lake sediment records (n = 11) along with lamina counting on high-resolution radiographs show sediment deposition frequencies ranging between annually to every 15 years. Down-core geochemical variability in a representative delta lake sediment core is consistent with historical variability in spring flood hydrology (variability in peak discharge, ice jamming, peak water levels). Comparison with earlier published Mackenzie River depth profiles shows that (i) lake sediments reflect the riverine surface suspended load, and (ii) hydrodynamic sorting patterns related to spring flood characteristics are reflected in the lake sediments. Bulk and molecular geochemistry of suspended particulate matter from the spring flood peak and lake sediments are relatively similar showing a mixture of modern higher-plant derived material, older terrestrial permafrost material, and old rock-derived material. This suggests that deltaic lake sedimentary records hold great promise as recorders of past (century-scale) riverine fluxes and may prove instrumental in shedding light on past behavior of arctic rivers, as well as how they respond to a changing climate.

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“…As atmospheric temperatures rise, the once semi-impermeable layers of permafrost begin to thaw, mobilizing a portion of this C pool by increasing the active layer depth, and then increasing riverine discharge and coastal erosion (Froese et al, 2008; Schuur et al, 2008; Feng et al, 2013; Holmes et al, 2013). This change in hydrology releases water, C, and nutrients, once trapped within the ice, into the coastal ocean.…”

Section: Introductionmentioning

confidence: 99%

Microbial Community Response to Terrestrially Derived Dissolved Organic Matter in the Coastal Arctic

et al. 2017

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Warming at nearly twice the global rate, higher than average air temperatures are the new ‘normal’ for Arctic ecosystems. This rise in temperature has triggered hydrological and geochemical changes that increasingly release carbon-rich water into the coastal ocean via increased riverine discharge, coastal erosion, and the thawing of the semi-permanent permafrost ubiquitous in the region. To determine the biogeochemical impacts of terrestrially derived dissolved organic matter (tDOM) on marine ecosystems we compared the nutrient stocks and bacterial communities present under ice-covered and ice-free conditions, assessed the lability of Arctic tDOM to coastal microbial communities from the Chukchi Sea, and identified bacterial taxa that respond to rapid increases in tDOM. Once thought to be predominantly refractory, we found that ∼7% of dissolved organic carbon and ∼38% of dissolved organic nitrogen from tDOM was bioavailable to receiving marine microbial communities on short 4 – 6 day time scales. The addition of tDOM shifted bacterial community structure toward more copiotrophic taxa and away from more oligotrophic taxa. Although no single order was found to respond universally (positively or negatively) to the tDOM addition, this study identified 20 indicator species as possible sentinels for increased tDOM. These data suggest the true ecological impact of tDOM will be widespread across many bacterial taxa and that shifts in coastal microbial community composition should be anticipated.

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Climate Change Impacts on the Hydrology and Biogeochemistry of Arctic Rivers

Cited by 89 publications

References 100 publications

Flux and Seasonality of Dissolved Organic Matter From the Northern Dvina (Severnaya Dvina) River, Russia

Flux and Seasonality of Dissolved Organic Matter From the Northern Dvina (Severnaya Dvina) River, Russia

Arctic Deltaic Lake Sediments As Recorders of Fluvial Organic Matter Deposition

Microbial Community Response to Terrestrially Derived Dissolved Organic Matter in the Coastal Arctic

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