scholarly journals Diatom flux reflects water-mass conditions on the southern Northwind Abyssal Plain, Arctic Ocean

2015 ◽  
Vol 12 (5) ◽  
pp. 1373-1385 ◽  
Author(s):  
J. Onodera ◽  
E. Watanabe ◽  
N. Harada ◽  
M. C. Honda
Keyword(s):  
Time Series ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Chukchi Sea ◽  
Sediment Traps ◽  
Central Canada ◽  
Oligotrophic Water ◽  
Western Arctic ◽  
Relationship Of ◽  
The Relationship

Abstract. We studied time-series fluxes of diatom particles from 4 October 2010 to 18 September 2012 using bottom-tethered moorings with two sediment traps deployed at 180 and 1300 m depths at Station NAP (75° N, 162° W; 1975 m water depth) in the western Arctic Ocean. This paper discusses on the relationship of time-series diatom fluxes to satellite-based sea-ice motion and simulated hydrographic variations. We observed clear maxima of the diatom valve flux in November–December of both 2010 and 2011, and in August 2011. Diatoms in samples were categorized into 98 taxa. The diatom flux maxima were characterized by many resting spores in November–December and by the sea-ice-associated diatom Fossula arctica in August 2011. These assemblages along with abundant clay minerals in the samples suggest a significant influence of shelf-origin materials transported by mesoscale eddies, which developed along the Chukchi Sea shelf break. In contrast, the fluxes of total mass and diatoms were reduced in summer 2012. We hypothesize that this suppression reflects the influx of oligotrophic water originating from the central Canada Basin. A physical oceanographic model demonstrated that oligotrophic surface water from the Beaufort Gyre was supplied to Station NAP from December 2011 to the early half of 2012.

scholarly journals Diatom flux reflects water-mass conditions on the southern Northwind Abyssal Plain, Arctic Ocean

2014 ◽  
Vol 11 (10) ◽  
pp. 15215-15250
Author(s):  
J. Onodera ◽  
E. Watanabe ◽  
N. Harada ◽  
M. C. Honda
Keyword(s):  
Arctic Ocean ◽  
Water Mass ◽  
Chukchi Sea ◽  
Mesoscale Eddies ◽  
Beaufort Gyre ◽  
Central Canada ◽  
Oligotrophic Water ◽  
Western Arctic ◽  
Oceanographic Model ◽  
Diatom Valve

Abstract. We studied time-series fluxes of diatom particles and their relationship to hydrographic variations from 4 October 2010 through 18 September 2012 using bottom-tethered sediment trap moorings deployed at Station NAP (75° N, 162° W; 1975 m water depth) in the western Arctic Ocean. We observed clear maxima of the diatom valve flux in November–December of both 2010 and 2011, and in August 2011. Diatoms in samples were categorized into 98 taxa. The diatom flux maxima were characterized by many resting spores in November–December and by the sea ice-associated diatom Fossula arctica in August 2011. These assemblages along with abundant clay minerals in the samples suggest a significant influence of shelf-origin materials transported by mesoscale eddies, which developed along the Chukchi Sea shelf break. In contrast, the fluxes of total mass and diatoms were reduced in summer 2012. We hypothesize that this suppression reflects the influx of oligotrophic water originating from the central Canada Basin. A physical oceanographic model demonstrated that oligotrophic surface water from the Beaufort Gyre was supplied to Station NAP from December 2011 to early half of 2012.

scholarly journals Seasonal and spatial variability of sea ice and phytoplankton biomarker flux in the Chukchi sea (western Arctic Ocean)

2019 ◽  
Vol 171 ◽  
pp. 22-37 ◽  
Author(s):  
Youcheng Bai ◽  
Marie-Alexandrine Sicre ◽  
Jianfang Chen ◽  
Vincent Klein ◽  
Haiyan Jin ◽  
...  
Keyword(s):  
Sea Ice ◽  
Spatial Variability ◽  
Arctic Ocean ◽  
Chukchi Sea ◽  
Western Arctic Ocean ◽  
Western Arctic

scholarly journals Low <i>p</i>CO<sub>2</sub> under sea-ice melt in the Canada Basin of the western Arctic Ocean

2017 ◽  
Vol 14 (24) ◽  
pp. 5727-5739 ◽  
Author(s):  
Naohiro Kosugi ◽  
Daisuke Sasano ◽  
Masao Ishii ◽  
Shigeto Nishino ◽  
Hiroshi Uchida ◽  
...  
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Arctic Ocean ◽  
Net Primary Production ◽  
Chukchi Sea ◽  
Canada Basin ◽  
Western Arctic Ocean ◽  
Riverine Discharge ◽  
Ice Melt ◽  
Western Arctic

Abstract. In September 2013, we observed an expanse of surface water with low CO2 partial pressure (pCO2sea) (< 200 µatm) in the Chukchi Sea of the western Arctic Ocean. The large undersaturation of CO2 in this region was the result of massive primary production after the sea-ice retreat in June and July. In the surface of the Canada Basin, salinity was low (< 27) and pCO2sea was closer to the air–sea CO2 equilibrium (∼  360 µatm). From the relationships between salinity and total alkalinity, we confirmed that the low salinity in the Canada Basin was due to the larger fraction of meltwater input (∼  0.16) rather than the riverine discharge (∼  0.1). Such an increase in pCO2sea was not so clear in the coastal region near Point Barrow, where the fraction of riverine discharge was larger than that of sea-ice melt. We also identified low pCO2sea (< 250 µatm) in the depth of 30–50 m under the halocline of the Canada Basin. This subsurface low pCO2sea was attributed to the advection of Pacific-origin water, in which dissolved inorganic carbon is relatively low, through the Chukchi Sea where net primary production is high. Oxygen supersaturation (> 20 µmol kg−1) in the subsurface low pCO2sea layer in the Canada Basin indicated significant net primary production undersea and/or in preformed condition. If these low pCO2sea layers surface by wind mixing, they will act as additional CO2 sinks; however, this is unlikely because intensification of stratification by sea-ice melt inhibits mixing across the halocline.

Summer N₂O dynamics in the western Arctic Ocean : Distributions, Processes, and Fluxes

2020 ◽  
Author(s):  
Seong-Su Kim ◽  
Sung-Ho Kang ◽  
Eun Jin Yang ◽  
Il-Nam Kim
Keyword(s):  
Arctic Ocean ◽  
Positive Relationship ◽  
Chukchi Sea ◽  
Negative Relationship ◽  
The Arctic ◽  
Biogeochemical Processes ◽  
High Solubility ◽  
Western Arctic Ocean ◽  
Western Arctic ◽  
Relationship Of

&lt;p&gt;We collect seawater samples from 32 stations for N&lt;sub&gt;2&lt;/sub&gt;O analysis between August 6 and August 25, during 2017 ARA08B cruise in western Arctic Ocean (WAO), covering from Southern Chukchi Sea (SC) to Northern Chukchi Sea (NC). At surface depth (~50 m), N&lt;sub&gt;2&lt;/sub&gt;O concentrations were 10.9&amp;#8210;19.4 nmol L&lt;sup&gt;-1&lt;/sup&gt;, and distinct pattern was observed between SC and NC. N&lt;sub&gt;2&lt;/sub&gt;O concentrations were increased from surface to bottom (~50 m) at SC, corresponding to positive relationship of &amp;#8710;N&lt;sub&gt;2&lt;/sub&gt;O (N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;measured &lt;/sub&gt;- N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;equilibrium&lt;/sub&gt;) with DIN (NO&lt;sub&gt;3&amp;#173;&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt; + NO&lt;sub&gt;2&lt;/sub&gt;&lt;sup&gt;-&lt;/sup&gt;) and negative relationship between &amp;#8710;N&lt;sub&gt;2&lt;/sub&gt;O and N&lt;sup&gt;*&lt;/sup&gt;. It suggests that nitrification and denitrification are the main processes to produce N&lt;sub&gt;2&lt;/sub&gt;O at SC. On the other hand, N&lt;sub&gt;2&lt;/sub&gt;O concentration at NC increased from the south to north, and remained vertically constant. It may be the result of physical processes such as dilution by sea ice melting water, and high solubility that affected by low temperature and low salinity. The highest N&lt;sub&gt;2&lt;/sub&gt;O concentrations were observed at intermediate depth (50&amp;#8210;200 m), ranging 13.4&amp;#8210;21.9 nmol L&lt;sup&gt;-1&lt;/sup&gt;. It would be determined by high solubility and active biogeochemical processes synthetically. Concentrations of N&lt;sub&gt;2&lt;/sub&gt;O were rapidly diminished to 400 m, ranging 10.2&amp;#8210;14.1 nmol L&lt;sup&gt;-1&lt;/sup&gt;, and did not be remarkably altered under 400 m, ranging 11.3&amp;#8210;13.7 nmol L&lt;sup&gt;-1&lt;/sup&gt;. It might be affected by advection of Atlantic Water (AW) and existence of Arctic Bottom Water (ABW), and influence of biogeochemical processes was negligible at deep and bottom depth (below 200 m). N&lt;sub&gt;2&lt;/sub&gt;O flux was calculated to determine that the WAO is sources or sinks region for atmospheric N&lt;sub&gt;2&lt;/sub&gt;O. Positive N&lt;sub&gt;2&lt;/sub&gt;O flux was observed at SC, and it indicate that N&lt;sub&gt;2&lt;/sub&gt;O gas is released to atmosphere at SC. Negative value of N&lt;sub&gt;2&lt;/sub&gt;O flux at NC suggest that atmospheric N&lt;sub&gt;2&lt;/sub&gt;O is absorbed into NC. Furthermore, positive relationship of N&lt;sub&gt;2&lt;/sub&gt;O flux with environmental parameters (temperature, salinity, and &amp;#8710;N&lt;sub&gt;2&lt;/sub&gt;O) also observed in WAO. These results provide comprehensive information of the spatial N&lt;sub&gt;2&lt;/sub&gt;O distribution and main processes which decide N&lt;sub&gt;2&lt;/sub&gt;O distribution in WAO, and also suggest that air-sea N&lt;sub&gt;2&lt;/sub&gt;O flux could be affected by changing environments of the Arctic Ocean.&lt;/p&gt;

scholarly journals Variability of sea ice cover in the Chukchi Sea (western Arctic Ocean) during the Holocene

2005 ◽  
Vol 20 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Anne de Vernal ◽  
Claude Hillaire-Marcel ◽  
Dennis A. Darby
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Chukchi Sea ◽  
Ice Cover ◽  
Western Arctic Ocean ◽  
The Holocene ◽  
Western Arctic

scholarly journals N2O dynamics in the western Arctic Ocean during the summer of 2017

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jang-Mu Heo ◽  
Seong-Su Kim ◽  
Sung-Ho Kang ◽  
Eun Jin Yang ◽  
Ki-Tae Park ◽  
...  
Keyword(s):  
Arctic Ocean ◽  
Environmental Changes ◽  
Chukchi Sea ◽  
Hot Spot ◽  
Open Water ◽  
Northern Region ◽  
The Arctic ◽  
Western Arctic Ocean ◽  
Deep Layers ◽  
Western Arctic

AbstractThe western Arctic Ocean (WAO) has experienced increased heat transport into the region, sea-ice reduction, and changes to the WAO nitrous oxide (N2O) cycles from greenhouse gases. We investigated WAO N2O dynamics through an intensive and precise N2O survey during the open-water season of summer 2017. The effects of physical processes (i.e., solubility and advection) were dominant in both the surface (0–50 m) and deep layers (200–2200 m) of the northern Chukchi Sea with an under-saturation of N2O. By contrast, both the surface layer (0–50 m) of the southern Chukchi Sea and the intermediate (50–200 m) layer of the northern Chukchi Sea were significantly influenced by biogeochemically derived N2O production (i.e., through nitrification), with N2O over-saturation. During summer 2017, the southern region acted as a source of atmospheric N2O (mean: + 2.3 ± 2.7 μmol N2O m−2 day−1), whereas the northern region acted as a sink (mean − 1.3 ± 1.5 μmol N2O m−2 day−1). If Arctic environmental changes continue to accelerate and consequently drive the productivity of the Arctic Ocean, the WAO may become a N2O “hot spot”, and therefore, a key region requiring continued observations to both understand N2O dynamics and possibly predict their future changes.

scholarly journals Timing of sea ice retreat can alter phytoplankton community structure in the western Arctic Ocean

2014 ◽  
Vol 11 (7) ◽  
pp. 1705-1716 ◽  
Author(s):  
A. Fujiwara ◽  
T. Hirawake ◽  
K. Suzuki ◽  
I. Imai ◽  
S.-I. Saitoh
Keyword(s):  
Community Structure ◽  
Sea Ice ◽  
Arctic Ocean ◽  
Phytoplankton Community ◽  
Phytoplankton Community Structure ◽  
Western Arctic Ocean ◽  
Phytoplankton Communities ◽  
Ice Retreat ◽  
Western Arctic ◽  
Sea Ice Retreat

Abstract. This study assesses the response of phytoplankton assemblages to recent climate change, especially with regard to the shrinking of sea ice in the northern Chukchi Sea of the western Arctic Ocean. Distribution patterns of phytoplankton groups in the late summers of 2008–2010 were analysed based on HPLC pigment signatures and, the following four major algal groups were inferred via multiple regression and cluster analyses: prasinophytes, diatoms, haptophytes and dinoflagellates. A remarkable interannual difference in the distribution pattern of the groups was found in the northern basin area. Haptophytes dominated and dispersed widely in warm surface waters in 2008, whereas prasinophytes dominated in cold water in 2009 and 2010. A difference in the onset date of sea ice retreat was evident among years–the sea ice retreat in 2008 was 1–2 months earlier than in 2009 and 2010. The spatial distribution of early sea ice retreat matched the areas in which a shift in algal community composition was observed. Steel-Dwass's multiple comparison tests were used to assess the physical, chemical and biological parameters of the four clusters. We found a statistically significant difference in temperature between the haptophyte-dominated cluster and the other clusters, suggesting that the change in the phytoplankton communities was related to the earlier sea ice retreat in 2008 and the corollary increase in sea surface temperatures. Longer periods of open water during the summer, which are expected in the future, may affect food webs and biogeochemical cycles in the western Arctic due to shifts in phytoplankton community structure.

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