scholarly journals Distributions of total and size-fractionated particulate <sup>210</sup>Po and <sup>210</sup>Pb activities along the North Atlantic GEOTRACES GA01 transect: GEOVIDE cruise

2018 ◽  
Vol 15 (17) ◽  
pp. 5437-5453 ◽  
Author(s):  
Yi Tang ◽  
Maxi Castrillejo ◽  
Montserrat Roca-Martí ◽  
Pere Masqué ◽  
Nolwenn Lemaitre ◽  
...  
Keyword(s):  
North Atlantic ◽  
Phase Correlation ◽  
Small Particles ◽  
Oxygen Utilization ◽  
Two Phase ◽  
The North ◽  
210Pb Activity ◽  
Vertical Distributions ◽  
The North Atlantic ◽  
Lead 210

Abstract. Vertical distributions of total and particulate polonium-210 (210Po) and lead-210 (210Pb) activities in the water column were measured at 11 stations in the North Atlantic during the GEOTRACES GA01 transect: GEOVIDE cruise in May–June 2014. Total 210Po activity was on average 24 % lower than 210Pb activity in the upper 100 m, and it was closer to unity in the mesopelagic (100–1000 m). The partitioning coefficients (Kd) along the transect suggest the preferential association of 210Po relative to 210Pb onto particles. The prominent role of small particles in sorption was confirmed by the observation that over 80 % of the particulate radionuclide activity was on small particles. To account for the observed surface water 210Po ∕ 210Pb disequilibria, particulate radionuclide activities and export of both small (1–53 µm) and large (>53 µm) particles must be considered. A comparison between the GEOVIDE total particulate 210Po ∕ 210Pb activity ratios (ARs) and the ratios in previous studies revealed a distinct geographic distribution, with lower particulate ARs in the high-latitude North Atlantic (including this study) and Arctic in relation to all other samples. For the samples where apparent oxygen utilization (AOU) was calculated at the same depth and time as the 210Po ∕ 210Pb AR (40 stations including this study), there was a two-phase correlation between the total particulate AR and AOU, likely reflecting the nature of the particles and demonstrating the forces of remineralization and radionuclide decay from particles as they age.

scholarly journals Distributions of <sup>210</sup>Po and <sup>210</sup>Pb activities along the North Atlantic GEOTRACES GA01 (GEOVIDE) cruise: partitioning between the particulate and dissolved phase

2018 ◽  
Author(s):  
Yi Tang ◽  
Maxi Castrillejo ◽  
Montserrat Roca-Martí ◽  
Pere Masqué ◽  
Nolwenn Lemaitre ◽  
...  
Keyword(s):  
North Atlantic ◽  
Phase Correlation ◽  
Small Particles ◽  
Oxygen Utilization ◽  
Two Phase ◽  
The North ◽  
210Pb Activity ◽  
Vertical Distributions ◽  
Partitioning Coefficients ◽  
The North Atlantic

Abstract. Vertical distributions of total and particulate 210Po and 210Pb activities in the water column were measured at eleven stations in the North Atlantic during the GEOTRACES GA01 GEOVIDE cruise in May–June 2014. Total 210Po activity was on average 24 % lower than 210Pb activity in the upper 100 m, and was closer to unity in the mesopelagic (100–1000 m). The partitioning coefficients (Kd) along the transect suggest the preferential association of 210Po relative to 210Pb onto particles. The prominent role of small particles in sorption was confirmed by the observation that over 80 % of the particulate radionuclide activity was on small particles. To account for the observed surface water 210Po / 210Pb disequilibria, particulate radionuclide activities and export of both small (1–53 μm) and large (> 53 μm) particles must be considered. A comparison between the GEOVIDE total particulate 210Po / 210Pb activity ratios (AR) and the ratios in previous studies revealed a distinct geographic distribution, with lower particulate AR in the high-latitude North Atlantic (including this study) and Arctic in relation to all other samples. For the samples where apparent oxygen utilization (AOU) was calculated at the same depth and time as the 210Po / 210Pb AR (40 stations including this study), there was a two-phase correlation between the total particulate AR and AOU demonstrating the competing forces of remineralization and radionuclide decay from particles as they age.

A southern and northern control on speleothem-based Asian summer monsoon variability during MIS 4

2019 ◽  
Vol 92 (3) ◽  
pp. 738-753
Author(s):  
Dianbing Liu ◽  
Shushuang Liu ◽  
Yifan Fang
Keyword(s):  
Summer Monsoon ◽  
North Atlantic ◽  
Southern China ◽  
Asian Summer Monsoon ◽  
Phase Correlation ◽  
The North ◽  
Asian Summer ◽  
The North Atlantic ◽  
Freshwater Inputs

AbstractA 20-year-resolution speleothem δ18O record from southern China reveals a detailed Asian summer monsoon (ASM) history between 73.6 and 62.3 ka. ASM changes during Interstadial 19 and late MIS 4 matched Greenland temperature variations but were antiphased with Antarctic temperatures. However, long-term strengthening of the ASM in early MIS 4 agrees well with the gradual Antarctic warming, when Greenland remained in a stable cold state. More specifically, the ASM was less variable during peak interstadials in contrast to striking instabilities during stadials. These observations suggest that the factors dominating ASM variability change through time. During early MIS 4, negligible freshwater perturbations occurred in the North Atlantic, and sea-surface temperatures in the low- to midlatitude Pacific Ocean reached the modern level. Thus, an expansion of the Intertropical Convergence Zone (ITCZ) was likely important for the long-term ASM rise. In late MIS 4, the antiphase correlation between ASM and Antarctic temperature could be attributed to freshwater inputs into the North Atlantic and a southerly positioned ITCZ. Consequently, meridional ITCZ shifts, although within a limited latitudinal band, would result in an antiphase relationship between interhemispheric climate changes. Otherwise, an in-phase correlation could be expected if the centroid of ITCZ is stable along the equator.

Observations on the Vertical Distribution of the Genus Acanthephyra (Crustacea: Decapoda) in the eastern North Atlantic, with particular reference to Species of the ‘purpurea’ Group.

1972 ◽  
Vol 73 ◽  
pp. 301-313 ◽  
Author(s):  
P. Foxton
Keyword(s):  
Vertical Distribution ◽  
North Atlantic ◽  
South Atlantic ◽  
The North ◽  
Mesopelagic Zone ◽  
Vertical Distributions ◽  
The North Atlantic ◽  
Eastern North Atlantic ◽  
The Vertical Distribution ◽  
Mesopelagic Species

SynopsisThe vertical distribution of pelagic decapods has been investigated at six positions, each located approximately at 10° interval of latitude between 11°N and 60°N in the eastern North Atlantic. An account of the day and night depth distribution of four mesopelagic species, Acanthephyra purpurea, A. pelagica, A. sexspinosa and A. acanthitelsonis, and four bathypelagic species, A. prionota, A. curtirostris, A. acutifrons and A. stylorostratis, is presented. The four mesopelagic species have vertical distributions which vary latitudinally in association with geographical gradients in temperature, the mesopelagic zone from about the latitude of 28°N cooling both polewards and equatorwards. It is concluded that environmental temperature is a major factor in controlling the vertical ranges of these species although other physical variables, principally light, must also be involved.A faunal boundary exists in the region of 18°N, where the North Atlantic species A. purpurea and A.pelagica are replaced by the Central and South Atlantic species A. sexspinosa and A. acanthitelsonis. The nature of the physical boundary is not clear, but it is tentatively proposed that it represents a relatively broad area where the North Atlantic Central Water and South Atlantic Central Water meet.

scholarly journals Nitrous oxide in the North Atlantic Ocean

2006 ◽  
Vol 3 (4) ◽  
pp. 607-619 ◽  
Author(s):  
S. Walter ◽  
H. W. Bange ◽  
U. Breitenbach ◽  
D. W. R. Wallace
Keyword(s):  
Nitrous Oxide ◽  
Atlantic Ocean ◽  
North Atlantic ◽  
North Atlantic Ocean ◽  
Tropical Region ◽  
Oxygen Utilization ◽  
Tropical Regions ◽  
The North ◽  
Comprehensive Picture ◽  
The North Atlantic

Abstract. In order to get a comprehensive picture of the distribution of nitrous oxide (N2O) in the North Atlantic Ocean, measurements of dissolved nitrous oxide were made during three cruises in the tropical, subtropical and cold-temperate North Atlantic Ocean in October/November 2002, March/April 2004, and May 2002, respectively. To account for the history of atmospheric N2O, we suggest a new depth-dependent calculation of excess N2O (ΔN2O). N2O depth profiles showed supersaturation throughout the water column with a distinct increasing trend from the cold-temperate to the tropical region. Lowest nitrous oxide concentrations, near equilibrium and with an average of 11.0±1.7 nmol L−1, were found in the cold-temperate North Atlantic where the profiles showed no clear maxima. Highest values up to 37.3 nmol L−1 occurred in the tropical North Atlantic with clear maxima at approximately 400 m. A positive correlation of nitrous oxide with nitrate, as well as excess nitrous oxide with the apparent oxygen utilization (AOU), was only observed in the subtropical and tropical regions. Therefore, we conclude that the formation of nitrous oxide via nitrification occurs in the tropical region rather than in the cold-temperate region of the North Atlantic Ocean

scholarly journals High export via small particles before the onset of the North Atlantic spring bloom

2016 ◽  
Vol 121 (9) ◽  
pp. 6929-6945 ◽  
Author(s):  
S. L. C. Giering ◽  
R. Sanders ◽  
A. P. Martin ◽  
C. Lindemann ◽  
K. O. Möller ◽  
...  
Keyword(s):  
North Atlantic ◽  
Spring Bloom ◽  
Small Particles ◽  
The North ◽  
The North Atlantic

The Currents of the North Atlantic

1892 ◽  
Vol 34 (872supp) ◽  
pp. 13940-13941
Author(s):  
Richard Beynon
Keyword(s):  
North Atlantic ◽  
The North ◽  
The North Atlantic

NATO adaptation to current challenges and mechanisms of Ukraine’s cooperation with the North Atlantic Treaty Organization

2019 ◽  
pp. 73-81
Author(s):  
Oleh Poshedin
Keyword(s):  
North Atlantic ◽  
Task Force ◽  
Response Force ◽  
Cyber Attack ◽  
Adaptation Measures ◽  
Joint Force ◽  
Security Environment ◽  
The North ◽  
The North Atlantic ◽  
Area Of Influence

The purpose of the article is to describe the changes NATO undergoing in response to the challenges of our time. Today NATO, as a key element of European and Euro-Atlantic security, is adapting to changes in the modern security environment by increasing its readiness and ability to respond to any threat. Adaptation measures include the components required to ensure that the Alliance can fully address the security challenges it might face. Responsiveness NATO Response Force enhanced by developing force packages that are able to move rapidly and respond to potential challenges and threats. As part of it, was established a Very High Readiness Joint Task Force, a new Allied joint force that deploy within a few days to respond to challenges that arise, particularly at the periphery of NATO’s territory. NATO emphasizes, that cyber defence is part of NATO’s core task of collective defence. A decision as to when a cyber attack would lead to the invocation of Article 5 would be taken by the North Atlantic Council on a case-by-case basis. Cooperation with NATO already contributes to the implementation of national security and defense in state policy. At the same time, taking into account that all decision-making in NATO based on consensus, Ukraine’s membership in the Alliance quite vague perspective. In such circumstances, in Ukraine you often can hear the idea of announcement of a neutral status. It is worth reminding that non-aligned status did not save Ukraine from Russian aggression. Neutral status will not accomplish it either. All talks about neutrality and the impossibility of Ukraine joining NATO are nothing but manipulations, as well as recognition of the Ukrainian territory as Russian Federation area of influence (this country seeks to sabotage the Euro-Atlantic movement of Ukraine). Think about it, Moldova’s Neutrality is enshrined in the country’s Constitution since 1994. However, this did not help Moldova to restore its territorial integrity and to force Russia to withdraw its troops and armaments from Transnistria.

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