Does the East Greenland Current exist in northern Fram Strait?

Richter, Maren; Appen, Wilken-Jon von; Wekerle, Claudia

doi:10.5194/os-2018-54

Cited by 14 publications

(34 citation statements)

References 44 publications

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“…Vertical tHg patterns at these stations differ from the vertical distribution of tHg in the western Fram Strait where more complex tHg profiles were found. We explain the complex tHg vertical pattern as a result of mixing between the AAW in the EGC and RAW (Richter et al, 2018). The outflowing waters of the EGC were enriched in tHg compared with tHg concentrations in the Irminger Sea (0.45 ± 0.51 pM, Cossa et al, 2018, Fig.…”

Section: Total Hg and Total Particulate Hgmentioning

confidence: 75%

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Mercury species export from the Arctic to the Atlantic Ocean

et al. 2020

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The Fram Strait is the only deep connection between the Arctic and Atlantic Oceans. The main water and mercury (Hg) fluxes between these oceans occur via the Fram Strait and Barents Sea Opening. Several Hg mass balance studies indicated a net Hg export from the Arctic to the Atlantic Ocean. However, in the absence of Hg measurements in the Fram Strait and Barents Sea Opening, these estimates were based on North Atlantic and central Arctic Ocean data alone. Here, we refine the Arctic total Hg (tHg) and methylated Hg (MeHg) mass budgets using new data acquired during the 2015 GEOTRACES (section GN04) TransArcII cruise in the Barents Sea Opening and the 2016 GEOTRACES (section GN05) GRIFF cruise, which covered the Fram Strait and Northeast Greenland Shelf. Total Hg increased westward along the Fram Strait transect, reaching the highest concentrations on the Northeast Greenland Shelf. Concentrations of tHg averaged 1.29 ± 0.43 pM in the East Greenland Current, while core waters of the West Spitsbergen Current had average values of 0.80 ± 0.26 pM. Using our new data, we estimate that 43 ± 9 Mg y-1 of tHg is transported to the Arctic Ocean in the core of the West Spitsbergen Current, while 54 ± 13 Mg y-1 of tHg is exported from the Arctic Ocean in the East Greenland Current and Recirculated Atlantic Water. This results in a net tHg export of 11 ± 8 Mg y-1 via the Fram Strait. We find a shallow MeHg maximum (at 150 m depth) in the East Greenland Current, in agreement to what was reported for the central Arctic Ocean and Canadian Arctic Archipelago. The West Spitsbergen Current is characterized by lower MeHg concentrations and a deeper MeHg maximum, that is located at approximately 1000 m depth. We estimate a net MeHg export of 6 ± 2 Mg y-1 from the Arctic Ocean via the Fram Strait, which is nearly half of the exported tHg. Most of the exported MeHg is in the form of DMHg (2:1 ratio of dimethylmercury to monomethylmercury). Previous studies reported lower MeHg proportions. Our observations show that the Arctic Ocean is producing and exporting MeHg to the Atlantic Ocean. In total, the Arctic Ocean exports about 18 Mg y-1 of tHg to the Nordic Seas and North Atlantic via the Fram Strait and Davis Strait, of which 7.5 Mg y-1 is in the MeHg form.

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Section: Total Hg and Total Particulate Hgmentioning

confidence: 75%

“…The hydrography in Fram Strait during the 2016 GRIFF cruise is described in detail by Richter et al (2018). Briefly, AW enters the Arctic Ocean via the Fram Strait as a part of the WSC ( The complex subsurface current system above the NEGS is described in detail by Schaffer et al (2017).…”

Section: Hydrological Settingmentioning

confidence: 99%

Mercury species export from the Arctic to the Atlantic Ocean

et al. 2020

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“…Partial CO2 pressure and pH were measured in the WSC only. Water masses and the fraction of Atlantic and Polar Water were characterized following Richter and colleagues 147 at each sampling event (Supplementary Methods). Sea ice concentrations derived from the Advanced Microwave Scanning Radiometer sensor AMSR-2 148 were downloaded from Institute of Environmental Physics, University of Bremen (https://seaice.uni-bremen.de/sea-ice-concentration-amsr-eamsr2).…”

Section: Methodsmentioning

confidence: 99%

The Polar Night Shift: Annual Dynamics and Drivers of Microbial Community Structure in the Arctic Ocean

Wietz¹,

Bienhold²,

Metfies³

et al. 2021

Preprint

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Change is a constant in the Arctic Ocean, with extreme seasonal differences in daylight, ice cover and temperature. The biodiversity and ecology of marine microbes across these extremes remain poorly understood. Here, using an array of autonomous samplers and sensors, we portray an annual cycle of microbial biodiversity, nutrient budgets and oceanography in the major biomes of the Fram Strait. In the ice-free West Spitsbergen Current, community turnover followed the solar cycle, with distinct separation of a productive summer state dominated by diatoms and carbohydrate-degrading bacteria, and a regenerative winter state dominated by heterotrophic Syndiniales, radiolarians, chemoautotrophic bacteria and archaea. Winter mixing of the water column replenishing nitrate, phosphate and silicate, and the onset of light were the major turning points. The summer succession of Phaeocystis, Grammonema and Thalassiosira coincided with ephemeral peaks of Formosa, Polaribacter and NS clades, indicating metabolic relationships between phytoplankton and bacteria. In the East Greenland Current, ice cover and greater sampling depth coincided with weaker seasonality, featuring weaker bloom/decay events and an ice-related winter microbiome. Low ice cover and advection of Atlantic Water coincided with diminished abundances of chemoautotrophic bacteria while Phaeocystis and Flavobacteriaceae increased, suggesting that Atlantification alters phytoplankton diversity and the biological carbon pump. Our findings promote the understanding of microbial seasonality in Arctic waters, illustrating the ecological importance of the polar night and providing an essential baseline of microbial dynamics in a region severely affected by climate change.

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“…Through this RAC, warm and salty Atlantic waters are transported westward across the strait (Gascard et al, 1995). Several studies imply that the recirculation may extend as far as or beyond 81ºN (Gascard et al, 1995;Kawasaki and Hasumi, 2016;Marnela et al, 2013;Richter et al, 2018;Schlichtholz and Houssais, 1999). Until recently the SB was supposed to be the main flow of AW into the Arctic (Manley, 1995).…”

Section: Study Areamentioning

confidence: 99%

“…Our sediment site, cored at ca. 290 m water depth in the easternmost part of the Westwind Trough (80.5ºN), is located within Arctic Atlantic Water (AAW) above the Deep Water (DW) and underneath the Polar Surface Water (PSW) (Figure 1c) (Richter et al, 2018). All discussed sediment records were obtained from sites within Atlantic-derived water masses (Figure 1b, c).…”

Section: Study Areamentioning

confidence: 99%

Environmental variability off NE Greenland (western Fram Strait) during the past 10,600 years

et al. 2020

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To reconstruct the climatic and paleoceanographic variability offshore Northeast Greenland during the last ~10 ka with multidecadal resolution, sediment core PS93/025 from the outermost North-East Greenland continental shelf (80.5°N) was studied by a variety of micropaleontological, sedimentological and isotopic methods. High foraminiferal fluxes, together with high proportions of ice-rafted debris and high Ca/Fe ratios, indicate a maximum in bioproductivity until ~8 ka related to a low sea-ice coverage. Sortable silt values, planktic foraminifer associations, and stable isotope data of planktic and benthic foraminifers suggest a strong westward advection of relatively warm Atlantic Water by the Return Atlantic Current during this time, with a noticeable bottom current activity. This advection may have been facilitated by a greater water depth at our site, resulting from postglacial isostatic depression. For the following mid-Holocene interval (ca. 8–5 ka), isotope data, lower foraminiferal fluxes and a shift in grain size maxima point to a lasting but successively decreasing Atlantic Water inflow, a weakening productivity, and a growing sea-ice coverage which is also revealed by the PIIIIP25 index. A final stage in the environmental development was reached at ~5 ka with the establishment of pre-industrial conditions. Low Ca/Fe ratios, low foraminiferal fluxes, low sortable silt values and the sea-ice indicating PIIIIP25 index point to a limited productivity and a weak Atlantic Water inflow by the Return Atlantic Current to our research area, as well as a higher and/or seasonally more extended sea-ice coverage during the Late Holocene. Two intervals with somewhat enhanced Atlantic Water advection around 2.0 and 1.0 ka are indicated by slightly increased foraminiferal fluxes and the reoccurrence of subpolar foraminifers. These intervals may correlate with the Roman Warm Period and the Medieval Climate Anomaly, as defined in the North Atlantic region.

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Does the East Greenland Current exist in northern Fram Strait?

Cited by 14 publications

References 44 publications

Mercury species export from the Arctic to the Atlantic Ocean

Mercury species export from the Arctic to the Atlantic Ocean

The Polar Night Shift: Annual Dynamics and Drivers of Microbial Community Structure in the Arctic Ocean

Environmental variability off NE Greenland (western Fram Strait) during the past 10,600 years

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