Freshwater balance and the sources of deep and bottom waters in the Arctic Ocean inferred from the distribution of H218O

Bauch, Dorothea; Schlosser, Peter; Fairbanks, Richard G.

doi:10.1016/0079-6611(95)00005-2

Cited by 247 publications

(241 citation statements)

References 41 publications

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“…River water and precipitation (meteoric water) as well as sea ice melt and brine from ice formation have been distinguished by the isotopic composition of oxygen (Østlund and Hut, 1984;Bauch et al, 1995;Melling and Moore, 1995;Macdonald et al, 1995;Yamamoto-Kawai et al, 2005;Lansard et al, 2012). However, away from the source regions, only the net effect of mixing between sea ice melt and brine from ice formation can be detected using this method.…”

Section: Tracers and Freshwater In The Arctic Oceanmentioning

confidence: 99%

“…Building on previous work (Bauch et al, 1995;Falck et al, 2005;Jones et al, 2008b), Dodd et al (2012) estimated the contributions of different water masses to liquid freshwater variability near 79 • N in the Western Fram Strait between 1998 and 2011. Dodd et al (2012) extended the work by Meredith et al (2001), Dodd et al (2009) and Rabe et al (2009), adding further years of observations and distinguishing Pacific Water fractions (concentrations) by considering nutrient measurements in addition to δ 18 O and salinity.…”

Section: Liquid Freshwater Components In the Western Fram Straitmentioning

confidence: 99%

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Liquid export of Arctic freshwater components through the Fram Strait 1998–2011

et al. 2013

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Abstract. We estimated the magnitude and composition of southward liquid freshwater transports in the East Greenland Current near 79 • N in the Western Fram Strait between 1998 and 2011. Previous studies have found this region to be an important pathway for liquid freshwater export from the Arctic Ocean to the Nordic Seas and the North Atlantic subpolar gyre.Our transport estimates are based on six hydrographic surveys between June and September and concurrent data from moored current meters. We combined concentrations of liquid freshwater, meteoric water (river water and precipitation), sea ice melt and brine from sea ice formation, and Pacific Water, presented in Dodd et al. (2012), with volume transport estimates from an inverse model. The average of the monthly snapshots of southward liquid freshwater transports between 10.6 • W and 4 • E is 100 ± 23 mSv (3160 ± 730 km 3 yr −1 ), relative to a salinity of 34.9. This liquid freshwater transport consists of about 130 % water from rivers and precipitation (meteoric water), 30 % freshwater from the Pacific, and −60 % (freshwater deficit) due to a mixture of sea ice melt and brine from sea ice formation.Pacific Water transports showed the highest variation in time, effectively vanishing in some of the surveys. Comparison of our results to the literature indicates that this was due to atmospherically driven variability in the advection of Pacific Water along different pathways through the Arctic Ocean. Variations in most liquid freshwater component transports appear to have been most strongly influenced by changes in the advection of these water masses to the Fram Strait. However, the local dynamics represented by the volume transports influenced the liquid freshwater component transports in individual years, in particular those of sea ice melt and brine from sea ice formation.Our results show a similar ratio of the transports of meteoric water and net sea ice melt as previous studies.

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Section: Tracers and Freshwater In The Arctic Oceanmentioning

confidence: 99%

Section: Liquid Freshwater Components In the Western Fram Straitmentioning

confidence: 99%

Liquid export of Arctic freshwater components through the Fram Strait 1998–2011

et al. 2013

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“…With its positive buoyancy this freshwater is one of the factors governing the formation of convective deep water in the North Atlantic and thus are of importance for the global ocean circulation and climate (Aagaard and Carmack, 1989;Guay et al, 2009). Based on salinity and oxygen isotopes, fractions of meteoric water, sea ice melt, and high salinity marine water may be discerned in surface waters (Bauch et al, 1995). The high salinity fraction can be divided in Atlantic and Pacific fractions by using initial phosphate corrected for mineralization with oxygen (PO 4 *) (Broecker, 1985;Ekwurzel et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

Utility of dissolved barium in distinguishing North American from Eurasian runoff in the Arctic Ocean

et al. 2012

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Dissolved barium has been shown to have the potential to distinguish Eurasian from North American (NA) river runoff. As part of the ARK-XXII/2 Polarstern expedition in summer 2007, Ba was analyzed in the Barents, Kara, Laptev seas, and the Eurasian Basins as well as the Makarov Basin up to the Alpha and Mendeleyev Ridges. By combining salinity, δ 18 O and initial phosphate corrected for mineralization with oxygen (PO 4 *) or N/P ratios we identified the water mass fractions of meteoric water, sea ice meltwater, and marine waters of Atlantic as well as Pacific origin in the upper water column. In all basins inside the lower halocline layer and the Arctic intermediate waters we find Ba concentrations close to those of the Fram Strait branch of the lower halocline (41-45 nM), reflecting the composition of the incoming Atlantic water. A layer of upper halocline water (UHW) with higher Ba concentrations (45-55 nM) is identified in the Makarov Basin. Atop of the UHW, the Surface Mixed Layer (SML), including the summer and winter mixed layers, has high concentrations of Ba (58-67 nM). In the SML of the investigated area of the central Arctic the meteoric fraction can be identified by assuming a conservative behavior of Ba to be primarily of Eurasian river origin. However, in productive coastal regions biological removal compromises the use of Ba to distinguish between Eurasian and NA rivers. As a consequence, the NA river water fraction is underestimated in productive surface waters or waters that have passed a productive region, whereas this fraction is overestimated in subsurface waters containing remineralised Ba, particularly when these waters have passed productive shelf regions. Especially in the Laptev Sea and small regions in the Barents Sea, Ba concentrations are low in surface waters. In the Laptev Sea exceptionally high Ba concentrations in shelf bottom waters indicate that Ba is removed from surface waters to deep waters by biological activity enhanced by increasing ice-free conditions as well as by scavenging by organic matter of terrestrial origin. We interpret high Ba concentrations in the UHW of the Makarov Basin to result from enrichment by remineralisation in bottom waters on the shelf of the Chukchi Sea and therefore the calculated NA runoff is an artefact. We conclude that no NA runoff can be demonstrated unequivocally anywhere during our expedition with the set of tracers considered here. Small contributions of NA runoff may have been masked by Ba depletion and could only be resolved by supportive tracers on the uptake history. We thus suggest that Ba has to be used with care as it can put limits but not yield quantitative water mass distributions. Only if the extra Ba inputs exceed the cumulative biological uptake the signal can be unequivocally attributed to NA runoff.

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“…Using the degree of fractionation determined by Melling and Moore (1995) Melling and Moore (1995); salinity from Untersteiner (1986). ‡ ␦ 18 O from Létolle et al (1993), Ö stlund andHut (1984), and Bauch et al (1995). § Mean winter concentration in the upper 500 m west of Bear Island derived from the Hudson cruise 82-001 (1984) and ESOP-95 (T. Johannessen pers.…”

Section: Resultsmentioning

confidence: 99%

“…A model of mixing between these end members is created using salinity, ␦ 18 O, and conservation of mass, based on the equations presented by Ö stlund and Hut (1984), Schlosser et al (1994), and Bauch et al (1995). From this model, the fraction of each water mass represented in the water sample is calculated.…”

Section: Resultsmentioning

confidence: 99%

Carbon utilization in the Eurasian sector of the Arctic Ocean

Olsson

Anderson

Frank

et al. 1999

Limnology & Oceanography

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Production and remineralization of carbon in the Eurasian sector have been estimated based on a combined data set of the expeditions. This sector includes the deep Nansen and Amundsen Basins and their linked shelf seas, i.e., the Barents, Kara, and Laptev Seas. The water masses in this region are composed of Atlantic water, river runoff, and sea ice-melt water. The fractionation between these source waters is elucidated from the ␦ 18 O-salinity relation and conservation of mass. By combining preformed nitrate concentrations of the source waters with the fractionation model and the measured nitrate concentrations, nitrate deficits and excesses are calculated. These concentrations are then converted to carbon equivalents by applying a C/N ratio, whereby a measure of apparent carbon utilization (ACU) is obtained. From the relative inventory of ACU along the slope and deep basin sections, we conclude that the shelf areas are the dominant productivity sites and that the productivity signal is transported to all water masses in the Eurasian Basin. The flux of utilized carbon from the Barents-Kara and Laptev Seas is about 0.022 Gton C yr Ϫ1 .The Arctic Ocean was once regarded as the most oligotrophic of oceans (e.g., Platt and Subba Rao 1975) due to extensive ice cover, low solar angle, and temperatures but is now considered as a potentially important site of carbon dioxide fixation (Wheeler et al. 1996). The marginal ice zones (MIZ) in particular, including polynyas, offer conditions that enhance photosynthetic activity (e.g., Alexander and Niebauer 1981;Rey and Loeng 1985;Sakshaug and Skjoldal 1989), especially if there is advection of nutrient-rich water into the MIZ area .The magnitude and extent of ice algal production is under current debate. A general consensus of the perennial ice cover inhibiting primary production prevails (e.g., SubbaAcknowledgments 1 Present address: Akvaplan-niva AS, Tromsø, Norway. The oceanographic groups and crew on board IB Oden and RV Polarstern are gratefully acknowledged for their assistance during the Oden-91 and ARK IX-4 expeditions. We are thankful to G.

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Freshwater balance and the sources of deep and bottom waters in the Arctic Ocean inferred from the distribution of H218O

Cited by 247 publications

References 41 publications

Liquid export of Arctic freshwater components through the Fram Strait 1998–2011

Liquid export of Arctic freshwater components through the Fram Strait 1998–2011

Utility of dissolved barium in distinguishing North American from Eurasian runoff in the Arctic Ocean

Carbon utilization in the Eurasian sector of the Arctic Ocean

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