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 Airborne Lidar Observations of a Spring Phytoplankton Bloom in the Western Arctic Ocean

2021 ◽  
Vol 13 (13) ◽  
pp. 2512
Author(s):  
James H. Churnside ◽  
Richard D. Marchbanks ◽  
Nathan Marshall
Keyword(s):  
Arctic Ocean ◽  
Phytoplankton Bloom ◽  
Chukchi Sea ◽  
Open Water ◽  
Horizontal Distribution ◽  
Airborne Lidar ◽  
The Arctic ◽  
Spring Phytoplankton Bloom ◽  
Vertical And Horizontal Distribution ◽  
Western Arctic

One of the most notable effects of climate change is the decrease in sea ice in the Arctic Ocean. This is expected to affect the distribution of phytoplankton as the ice retreats earlier. We were interested in the vertical and horizontal distribution of phytoplankton in the Chukchi Sea in May. Measurements were made with an airborne profiling lidar that allowed us to cover large areas. The lidar profiles showed a uniform distribution of attenuation and scattering from the surface to the limit of lidar penetration at a depth of about 30 m. Both parameters were greater in open water than under the ice. Depolarization of the lidar decreased as attenuation and scattering increased. A cluster analysis of the 2019 data revealed four distinct clusters based on depolarization and lidar ratio. One cluster was associated with open water, one with pack ice, one with the waters along the land-fast ice, and one that appeared to be scattered throughout the region. The first three were likely the result of different assemblages of phytoplankton, while the last may have been an artifact of thin fog in the atmosphere.

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

<p>We collect seawater samples from 32 stations for N<sub>2</sub>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<sub>2</sub>O concentrations were 10.9‒19.4 nmol L<sup>-1</sup>, and distinct pattern was observed between SC and NC. N<sub>2</sub>O concentrations were increased from surface to bottom (~50 m) at SC, corresponding to positive relationship of ∆N<sub>2</sub>O (N<sub>2</sub>O<sub>measured </sub>- N<sub>2</sub>O<sub>equilibrium</sub>) with DIN (NO<sub>3­</sub><sup>-</sup> + NO<sub>2</sub><sup>-</sup>) and negative relationship between ∆N<sub>2</sub>O and N<sup>*</sup>. It suggests that nitrification and denitrification are the main processes to produce N<sub>2</sub>O at SC. On the other hand, N<sub>2</sub>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<sub>2</sub>O concentrations were observed at intermediate depth (50‒200 m), ranging 13.4‒21.9 nmol L<sup>-1</sup>. It would be determined by high solubility and active biogeochemical processes synthetically. Concentrations of N<sub>2</sub>O were rapidly diminished to 400 m, ranging 10.2‒14.1 nmol L<sup>-1</sup>, and did not be remarkably altered under 400 m, ranging 11.3‒13.7 nmol L<sup>-1</sup>. 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<sub>2</sub>O flux was calculated to determine that the WAO is sources or sinks region for atmospheric N<sub>2</sub>O. Positive N<sub>2</sub>O flux was observed at SC, and it indicate that N<sub>2</sub>O gas is released to atmosphere at SC. Negative value of N<sub>2</sub>O flux at NC suggest that atmospheric N<sub>2</sub>O is absorbed into NC. Furthermore, positive relationship of N<sub>2</sub>O flux with environmental parameters (temperature, salinity, and ∆N<sub>2</sub>O) also observed in WAO. These results provide comprehensive information of the spatial N<sub>2</sub>O distribution and main processes which decide N<sub>2</sub>O distribution in WAO, and also suggest that air-sea N<sub>2</sub>O flux could be affected by changing environments of the Arctic Ocean.</p>

scholarly journals Flux variations and vertical distributions of siliceous Rhizaria (Radiolaria and Phaeodaria) in the western Arctic Ocean: indices of environmental changes

2015 ◽  
Vol 12 (6) ◽  
pp. 2019-2046 ◽  
Author(s):  
T. Ikenoue ◽  
K. R. Bjørklund ◽  
S. B. Kruglikova ◽  
J. Onodera ◽  
K. Kimoto ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
Environmental Changes ◽  
Cold Water ◽  
North Pacific Ocean ◽  
Mesh Size ◽  
Open Water ◽  
Ice Cover ◽  
Western Arctic Ocean ◽  
Western Arctic

Abstract. The vertical distribution of radiolarians was investigated using a vertical multiple plankton sampler (100–0, 250–100, 500–250, and 1000–500 m water depths, 62 μm mesh size) at the Northwind Abyssal Plain and southwestern Canada Basin in September 2013. To investigate seasonal variations in the flux of radiolarians in relation to sea ice and water masses, a time-series sediment trap system was moored at Station NAP (75°00´ N, 162°00´ W; bottom depth 1975 m) in the western Arctic Ocean during October 2010–September 2012. The radiolarian flux was comparable to that in the North Pacific Ocean. Amphimelissa setosa was dominant during the season with open water as well as at the beginning and end of the seasons with sea-ice cover. During the sea-ice-cover season, however, oligotrophic and cold-water-tolerant actinommids were dominant, productivity of Radiolaria was lower, and species diversity was greater. These suggest that the dynamics of sea ice are a major factor affecting the productivity, distribution, and composition of the radiolarian fauna.

scholarly journals Transport of trace metals (Mn, Fe, Ni, Zn and Cd) in the western Arctic Ocean (Chukchi Sea and Canada Basin) in late summer 2012

2016 ◽  
Vol 116 ◽  
pp. 236-252 ◽  
Author(s):  
Yoshiko Kondo ◽  
Hajime. Obata ◽  
Nanako Hioki ◽  
Atsushi Ooki ◽  
Shigeto Nishino ◽  
...  
Keyword(s):  
Trace Metals ◽  
Arctic Ocean ◽  
Chukchi Sea ◽  
Late Summer ◽  
Canada Basin ◽  
Western Arctic Ocean ◽  
Western Arctic

scholarly journals Dissolved organic matter composition and bioavailability reflect ecosystem productivity in the Western Arctic Ocean

2012 ◽  
Vol 9 (7) ◽  
pp. 9571-9601 ◽  
Author(s):  
Y. Shen ◽  
C. G. Fichot ◽  
R. Benner
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Arctic Ocean ◽  
Surface Waters ◽  
Microbial Growth ◽  
Chukchi Sea ◽  
Ecosystem Productivity ◽  
Western Arctic Ocean ◽  
Western Arctic ◽  
High Yields

Abstract. Dissolved organic carbon (DOC) and total dissolved amino acids (TDAA) were measured in high (Chukchi Sea) and low (Beaufort Sea) productivity regions of the Western Arctic Ocean to investigate the composition and bioavailability of dissolved organic matter (DOM). Concentrations and DOC-normalized yields of TDAA in Chukchi surface waters were relatively high, indicating an accumulation of bioavailable DOM. High yields of TDAA were also observed in the upper halocline of slope and basin waters, indicating off-shelf transport of bioavailable DOM from the Chukchi Sea. In contrast, concentrations and yields of TDAA in Beaufort surface waters were relatively low, indicting DOM was of limited bioavailability. Yields of TDAA in the upper halocline of slope and basin waters were also low, suggesting the Beaufort is not a major source of bioavailable DOM to slope and basin waters. In shelf waters of both systems, elevated concentrations and yields of TDAA were often observed in waters with higher chlorophyll concentrations and productivity. Surface concentrations of DOC were similar (p > 0.05) in the two systems despite the contrasting productivity, but concentrations and yields of TDAA were significantly higher (p < 0.0001) in the Chukchi than in the Beaufort. Unlike bulk DOC, TDAA concentrations and yields reflect ecosystem productivity in the Western Arctic. The occurrence of elevated bioavailable DOM concentrations in the Chukchi implies an uncoupling between the biological production and utilization of DOM and has important implications for sustaining heterotrophic microbial growth and diversity in oligotrophic waters of the Central Arctic basins.

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.

Importance of Seasonal Sea Ice in the Western Arctic Ocean to the Arctic and Global Microplastic Budgets

2021 ◽  
pp. 125971
Author(s):  
Seung-Kyu Kim ◽  
Hee-Jee Lee ◽  
Ji-Su Kim ◽  
Sung-Ho Kang ◽  
Eun-Jin Yang ◽  
...  
Keyword(s):  
Sea Ice ◽  
Arctic Ocean ◽  
The Arctic ◽  
Western Arctic Ocean ◽  
Western Arctic
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