Ocean circulation and freshwater pathways in the Arctic Mediterranean based on a combined Nd isotope, REE and oxygen isotope section across Fram Strait

Laukert, Georgi; Bauch, Dorothea; Hathorne, Ed C; Rabe, Benjamin; Appen, Wilken-Jon von; Wegner, Carolyn; Zieringer, Moritz; Kassens, Heidemarie

doi:10.1016/j.gca.2016.12.028

Cited by 51 publications

(70 citation statements)

References 93 publications

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“…Water contribution of the ECS to adjacent areas were estimated by a simple mixing model and (Table S2) (Laukert et al, ). We assume the MSW ( S = 31.71, T = 23.3°C, [Nd] = 28.9 pmol/kg, and ε Nd = −11.3 ± 0.5) and KW as the end‐members and calculate the contribution of MSW to the northwestern Pacific about 6 ± 3%.…”

Section: Resultsmentioning

confidence: 99%

Water Mass Analysis and End‐Member Mixing Contribution Using Coupled Radiogenic Nd Isotopes and Nd Concentrations: Interaction Between Marginal Seas and the Northwestern Pacific

Chen

Zhang

2018

Geophysical Research Letters

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We analyzed neodymium (Nd) concentrations and isotopic compositions (εNd) in seawater of the northwestern Pacific marginal seas and adjacent waters. The values of εNd in the surface water increase from the Changjiang River Estuary to the outer shelf. This increase in εNd from −12.8 to −7.7 is mainly influenced by the terrestrial source and water mixing. Changjiang Diluted Water contributes more than 20% of the volumetric flux in most regions' surface waters during our investigation. The contribution of Kuroshio Subsurface Water to the Changjiang River Estuary is more than 80% in the southern study area. Estimated water contributions from the East China Sea to the northwestern Pacific and the Sea of Japan are approximately 6% and 10%, respectively. These results imply that the East China Sea is a significant source of material to the northwestern Pacific.

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Section: Resultsmentioning

confidence: 99%

Water Mass Analysis and End‐Member Mixing Contribution Using Coupled Radiogenic Nd Isotopes and Nd Concentrations: Interaction Between Marginal Seas and the Northwestern Pacific

Chen

Zhang

2018

Geophysical Research Letters

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“…Thus, at intermediate depths, both DSOW and ISOW are fed by water from the AO and Nordic Seas, whereby the DSOW has a higher contribution of surface polar waters from the AO than the ISOW (Hansen and Østerhus, 2000). According to Laukert et al (2017), based on neodymium isotopes, the DAAW that leaves the AO is the precursor of DSOW. Based on our data, the DAAW has the highest average δ 30 Si-DSi found in the Central AO with an average δ 30 Si-DSi of 1.62 ± 0.06 (2SEM, n = 21).…”

Section: The Arctic Ocean In the Context Of The Global Meridional Ovementioning

confidence: 99%

The Influence of Water Mass Mixing and Particle Dissolution on the Silicon Cycle in the Central Arctic Ocean

2020

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The use of the silicon isotope composition of dissolved silicon (δ 30 Si-DSi) to understand the marine silicon cycle has been increasing in recent years. Here we present δ 30 Si-DSi and δ 30 Si of biogenic silica (δ 30 Si-bSiO 2) in the intermediate to deep waters of the Central Arctic Ocean (AO) aiming at investigating in more detail the relative influence of water mass mixing and particle flux on the Si cycle in the AO. Comparing the δ 30 Si-DSi with the water mass composition derived from Optimum Multiparameter (OMP) analysis, we were able to test the influence of the water masses in the δ 30 Si-DSi distribution. We were able to show the dominant Atlantic Water (AW) influence at the stations close to the Fram Strait (station 32 and 40, δ 30 Si-DSi = 1.51 ± 0.11 , 2SEM, n = 3) and the only small δ 30 Si-DSi modification when compared to the endmember value from a previous study (δ 30 Si-DSi = 1.55). The Dense Arctic Atlantic Water, dominating from 200 to 500 m water depth (except for stations 32 and 40, where it was present only at 500 m), was marked by heavier δ 30 Si-DSi of 1.62 ± 0.06 (2SEM, n = 21). This is probably due to the influence of entraining equally dense water from the shelves. Due to productivity and Si utilization on the shelves, both water and bSiO 2 , that were transported laterally into the Central AO, were characterized by higher δ 30 Si, with δ 30 Si-bSiO 2 of 1.64 ± 0.13 (2SEM, n = 7). Particle dissolution at greater depths did not play a major role in the δ 30 Si-DSi of deep waters due to the low bSiO 2 concentrations at these greater depths. Outflowing water masses from the AO present different δ 30 Si-DSi, with lower values around 1.46 originating from the Central AO influencing predominantly DSOW and ISOW, and higher values around 2 originating from the Canadian AO influencing predominantly LSW. Those signatures correspond with the δ 30 Si-DSi found in the North Atlantic. Consequently, the AO potentially presents several isotopically different endmembers that contribute to the deep water formed in the North Atlantic.

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“…Original datasets are described as follows. For Davis Strait see Lee et al (2004) (with δ 18 O by Kumiko Azetsu-Scott, Department of Fisheries and Oceans, Bedford Institute of Oceanography). For Bering Strait see Woodgate et al (2015).…”

Section: Measurementsmentioning

confidence: 99%

Arctic freshwater fluxes: sources, tracer budgets and inconsistencies

et al. 2019

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Abstract. The net rate of freshwater input to the Arctic Ocean has been calculated in the past by two methods: directly, as the sum of precipitation, evaporation and runoff, an approach hindered by sparsity of measurements, and by the ice and ocean budget method, where the net surface freshwater flux within a defined boundary is calculated from the rate of dilution of salinity, comparing ocean inflows with ice and ocean outflows. Here a third method is introduced, the geochemical method, as a modification of the budget method. A standard approach uses geochemical tracers (salinity, oxygen isotopes, inorganic nutrients) to compute “source fractions” that quantify a water parcel's constituent proportions of seawater, freshwater of meteoric origin, and either sea ice melt or brine (from the freezing-out of sea ice). The geochemical method combines the source fractions with the boundary velocity field of the budget method to quantify the net flux derived from each source. Here it is shown that the geochemical method generates an Arctic Ocean surface freshwater flux, which is also the meteoric source flux, of 200±44 mSv (1 Sv=106 m3 s−1), statistically indistinguishable from the budget method's 187±44 mSv, so that two different approaches to surface freshwater flux calculation are reconciled. The freshwater export rate of sea ice (40±14 mSv) is similar to the brine export flux, due to the “freshwater deficit” left by the freezing-out of sea ice (60±50 mSv). Inorganic nutrients are used to define Atlantic and Pacific seawater categories, and the results show significant non-conservation, whereby Atlantic seawater is effectively “converted” into Pacific seawater. This is hypothesized to be a consequence of denitrification within the Arctic Ocean, a process likely becoming more important with seasonal sea ice retreat. While inorganic nutrients may now be delivering ambiguous results on seawater origins, they may prove useful to quantify the Arctic Ocean's net denitrification rate. End point degeneracy is also discussed: multiple property definitions that lie along the same “mixing line” generate confused results.

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Ocean circulation and freshwater pathways in the Arctic Mediterranean based on a combined Nd isotope, REE and oxygen isotope section across Fram Strait

Cited by 51 publications

References 93 publications

Water Mass Analysis and End‐Member Mixing Contribution Using Coupled Radiogenic Nd Isotopes and Nd Concentrations: Interaction Between Marginal Seas and the Northwestern Pacific

Water Mass Analysis and End‐Member Mixing Contribution Using Coupled Radiogenic Nd Isotopes and Nd Concentrations: Interaction Between Marginal Seas and the Northwestern Pacific

The Influence of Water Mass Mixing and Particle Dissolution on the Silicon Cycle in the Central Arctic Ocean

Arctic freshwater fluxes: sources, tracer budgets and inconsistencies

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