The residence times of trace elements determined in the surface Arctic Ocean during the 2015 US Arctic GEOTRACES expedition

Kadko, David; Aguilar-Islas, Ana M.; Bolt, Channing; Buck, Clifton S.; Fitzsimmons, Jessica N.; Jensen, Laramie T.; Landing, William M.; Marsay, Christopher M.; Rember, Robert; Shiller, Alan M.; Whitmore, Laura M.; Anderson, Robert F.

doi:10.1016/j.marchem.2018.10.011

Cited by 36 publications

(47 citation statements)

References 67 publications

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“…The importance of sedimentary dFe supply to Fram Strait region was also indicated from the distribution of dissolved Mn (Fig. 3 f), which derives primarily from sediments and shows maxima in (i) the surface EGC where the influence of the Transpolar Drift is expected 85 , (ii) near the glacier termini on the NE Greenland Shelf, and (iii) on the continental slopes of Svalbard 86 – 88 .…”

Section: Resultsmentioning

confidence: 90%

The influence of Arctic Fe and Atlantic fixed N on summertime primary production in Fram Strait, North Greenland Sea

Krisch

Browning

Graeve

et al. 2020

Sci Rep

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Climate change has led to a ~ 40% reduction in summer Arctic sea-ice cover extent since the 1970s. Resultant increases in light availability may enhance phytoplankton production. Direct evidence for factors currently constraining summertime phytoplankton growth in the Arctic region is however lacking. GEOTRACES cruise GN05 conducted a Fram Strait transect from Svalbard to the NE Greenland Shelf in summer 2016, sampling for bioessential trace metals (Fe, Co, Zn, Mn) and macronutrients (N, Si, P) at ~ 79°N. Five bioassay experiments were conducted to establish phytoplankton responses to additions of Fe, N, Fe + N and volcanic dust. Ambient nutrient concentrations suggested N and Fe were deficient in surface seawater relative to typical phytoplankton requirements. A west-to-east trend in the relative deficiency of N and Fe was apparent, with N becoming more deficient towards Greenland and Fe more deficient towards Svalbard. This aligned with phytoplankton responses in bioassay experiments, which showed greatest chlorophyll-a increases in + N treatment near Greenland and + N + Fe near Svalbard. Collectively these results suggest primary N limitation of phytoplankton growth throughout the study region, with conditions potentially approaching secondary Fe limitation in the eastern Fram Strait. We suggest that the supply of Atlantic-derived N and Arctic-derived Fe exerts a strong control on summertime nutrient stoichiometry and resultant limitation patterns across the Fram Strait region.

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Section: Resultsmentioning

confidence: 90%

The influence of Arctic Fe and Atlantic fixed N on summertime primary production in Fram Strait, North Greenland Sea

Krisch

Browning

Graeve

et al. 2020

Sci Rep

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“…For this reason, we use the average aerosol 7 Be activity rather than the "snapshot" aerosol observations to calculate the bulk deposition velocities. Values of V b derived in this manner for the PMT cruise are plotted against rainfall rate in Kadko et al, 2020); Bermuda (diamond, Kadko et al, 2015); and the Arctic (square, Kadko et al, 2016Kadko et al, , 2019. The upper and lower 95% confidence intervals (dashed lines) around the linear regression trend line are shown.…”

Section: Resultsmentioning

confidence: 99%

“…Detailed methodology and error analyses are presented in Huffman et al (1997). The rainfall rates used in the following discussions were based on the weighted average at each location, which included the rainfall rate for the month of sampling and the prior 3 months each Kadko et al, 2020); Bermuda (diamond, Kadko et al, 2015); and the Arctic (square, Kadko et al, 2016Kadko et al, , 2019. diminished by an exponential term containing the decay constant of 7 Be, that is, weighted against the decay lifetime of 7 Be deposited during each month (equation 4).…”

Section: Rainfall Analysismentioning

confidence: 99%

“…Furthermore, it has been shown that the integrated rate of decay of 7 Be in the upper ocean (i.e., the 7 Be inventory in the water column multiplied by the radioactive decay constant for 7 Be) is equal to its flux to the ocean by wet and dry deposition (Aaboe et al, 1981;Kadko & Prospero, 2011;Kadko et al, 2015;Kadko et al, 2019). Under steady-state conditions in the absence of upwelling and when particle export of 7 Be is negligible (conditions characteristic of most open ocean regions; Kadko & Johns, 2011;Kadko, 2017),…”

Section: Introductionmentioning

confidence: 99%

“…Because it is associated with submicrometer aerosols, the deposition of aerosol 7 Be is dominated by rainfall scavenging, and 7 Be deposition rates correlate with the rate of precipitation (e.g., Kadko & Prospero, 2011;Kim et al, 1999;Olsen et al, 1985;Peng et al, 2019;Uematsu et al, 1994;Young & Silker, 1980). The 7 Be-derived bulk deposition velocities (equation 3) are plotted against rainfall rate ( Figure S1 in the supporting information) for the Arctic (low rainfall region, 1,190 m/day; Kadko et al, 2016Kadko et al, , 2019 and for Bermuda…”

Section: Introductionmentioning

confidence: 99%

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Quantifying Atmospheric Trace Element Deposition Over the Ocean on a Global Scale With Satellite Rainfall Products

Kadko

Landing

Buck

2020

Geophysical Research Letters

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Atmospheric input of trace element micronutrients to the oceans is difficult to determine, as even with collection of high-quality aerosol chemical concentrations, such data by themselves cannot yield deposition rates. To transform these concentrations into rates, a method of determining flux by applying an appropriate deposition velocity is required. A recently developed method based on the natural radionuclide 7 Be has provided a means to estimate the bulk (wet + dry) deposition velocity (V b ) required for this calculation. Here, water column 7 Be inventories and aerosol 7 Be concentrations collected during the 2018 US GEOTRACES Pacific Meridional Transect are presented. We use these data together with those from other ocean basins to derive a global relationship between rain rate (m/yr) and bulk deposition velocity (m/day), such that V b = 999 ± 96 × Rain rate + 1,040 ± 136 (R 2 = 0.81). Thus, with satellite-derived rainfall estimates, a means to calculate aerosol bulk deposition velocities is provided.Plain Language Summary Atmospheric input of trace element micronutrients to the global ocean such as iron (Fe), cobalt (Co), and Zinc (Zn) is difficult to determine. Even with collection of high-quality aerosol chemical concentrations, such data by themselves cannot yield rates of deposition. A recently developed method based on the natural radionuclide 7 Be, which is deposited to the surface ocean, has provided a means to estimate the bulk (wet + dry) deposition velocity (V b ) required for this calculation. In this work, water column 7 Be inventories and aerosol 7 Be concentrations collected during the 2018 US GEOTRACES Pacific Meridional Transect are presented. We use these data together with those from other ocean basins to derive a global relationship between rain rate (m/yr) and bulk deposition velocity (m/day), such that V b = 999 × Rain rate + 1,040 (R 2 = 0.81). Thus, deposition velocity to an ocean region can be estimated from rainfall rate. This information is critical for evaluating limitations on phytoplankton growth and the strength of the biological carbon pump and represents an important input to ocean biogeochemical models.

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Continental and glacial runoff fingerprints in the Canadian Arctic Archipelago, the Inuit Nunangat ocean

Rogalla

Allen

Colombo

et al. 2023

Preprint

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Rising temperatures and an acceleration of the hydrological cycle due to climate change are increasing river discharge, causing permafrost thaw, glacial melt, and a shift to a groundwater-dominated system in the Arctic. These changes are funnelled to coastal regions of the Arctic Ocean where the implications for the distributions of nutrients and biogeochemical constituents are unclear. In this study, we investigate the impact of terrestrial runoff on marine biogeochemistry in Inuit Nunangat (the Canadian Arctic Archipelago) — a key pathway for transport and modification of waters from the Arctic Ocean to the North Atlantic — using sensitivity experiments from 2002-2020 with an ocean model of manganese (Mn). The micronutrient Mn traces terrestrial runoff and the modification of geochemical constituents of runoff during transit. The heterogeneity in Arctic runoff composition creates distinct terrestrial fingerprints of influence in the ocean: continental runoff influences Mn in the southwestern Archipelago, glacial runoff dominates the northeast, and their influence co-occurs in central Parry Channel. Glacial runoff carries micronutrients southward from Nares Strait in the late summer and may help support longer phytoplankton blooms in the Pikialasorsuaq polynya. Enhanced glacial runoff may increase micronutrients delivered downstream to Baffin Bay, accounting for up to 18% of dissolved Mn fluxes seasonally and 6% annually. These findings highlight how climate induced changes to terrestrial runoff may impact the geochemical composition of the marine environment, and will help to predict the extent of these impacts from ongoing alterations of the Arctic hydrological cycle.

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The residence times of trace elements determined in the surface Arctic Ocean during the 2015 US Arctic GEOTRACES expedition

Cited by 36 publications

References 67 publications

The influence of Arctic Fe and Atlantic fixed N on summertime primary production in Fram Strait, North Greenland Sea

The influence of Arctic Fe and Atlantic fixed N on summertime primary production in Fram Strait, North Greenland Sea

Quantifying Atmospheric Trace Element Deposition Over the Ocean on a Global Scale With Satellite Rainfall Products

Continental and glacial runoff fingerprints in the Canadian Arctic Archipelago, the Inuit Nunangat ocean

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