Organic nutrients and excess nitrogen in the North Atlantic subtropical gyre

Abstract. To enable an accurate estimate of total excess nitrogen (N) in the North Atlantic, a new tracer TNxs is defined, which includes the contribution of organic nutrients to the assessment of N:P stoichiometric anomalies. We measured the spatial distribution of TNxs within the subtropical North Atlantic using data from a trans-Atlantic section across 24.5° N occupied in 2004. We then employ three different approaches to infer rates of total excess nitrogen accumulation using pCFC-12 derived ventilation ages (a TNxs vertical integration, a one end-member and a two-end member mixing model). Despite some variability among the different methods the dissolved organic nutrient fraction always contributes to about half of the TNxs accumulation, which is in the order of 9.38±4.18×1011 mol N y−1. We suggest that neglecting organic nutrients in stoichiometric balances of the marine N and P inventories can lead to systematic errors when estimating deviations of nitrogen excess or deficit relative to the Redfield ratio in the oceans. For the North Atlantic the inclusion of the organic fraction to the excess nitrogen pool leads to an upward revision of the N supply by N2 fixation to 10.2±6.9×1011 mol N y−1.

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Organic nutrients and excess nitrogen in the North Atlantic subtropical gyre

Biogeosciences Discussions ◽

10.5194/bgd-5-685-2008 ◽

2008 ◽

Vol 5 (1) ◽

pp. 685-724 ◽

Cited By ~ 1

Author(s):

A. Landolfi ◽

A. Oschlies ◽

R. Sanders

Keyword(s):

North Atlantic ◽

N2 Fixation ◽

Accurate Estimate ◽

Nitrogen Accumulation ◽

Excess Nitrogen ◽

The North ◽

The North Atlantic ◽

Organic Nutrients ◽

Using Data ◽

Nitrogen Excess

Abstract. To enable an accurate estimate of total excess nitrogen (N) in the North Atlantic a new tracer, TNxs, is defined which includes the contribution of organic nutrients to the assessment of N:P stoichiometric anomalies. We estimate the spatial distribution of TNxs within the North Atlantic using data from a trans-Atlantic section across 24.5° N conducted in 2004. We then employ three different approaches to infer rates of total excess nitrogen accumulation using pCFC-12 derived ventilation ages (a TNxs vertical integration, a one end-member and a two-end member mixing model). Despite some variability among the different methods the dissolved organic nutrient fraction always contributes to about half of the TNxs accumulation, which is in the order of 9.38±4.18×1011 mol N y−1. Here we suggest that neglecting organic nutrients in stoichiometric balances of the marine N and P inventories can lead to systematic errors when estimating a nitrogen excess or deficit relative to the Redfield ratio in the oceans. For the North Atlantic the inclusion of the organic fraction leads to an upward revision of the N supply by N2 fixation to 10.2±6.9×1011 mol N y−1. This enhanced estimate of nitrogen fixation reconciles the geochemical estimates of N2 fixation derived from excess nitrate and the direct estimates from N2 fixation measurements.

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Modeling the nutrient and carbon cycles of the North Atlantic: 2. New production, particle fluxes, CO2gas exchange, and the role of organic nutrients

Journal of Geophysical Research Atmospheres ◽

10.1029/jc094ic09p12781 ◽

1989 ◽

Vol 94 (C9) ◽

pp. 12781 ◽

Cited By ~ 23

Author(s):

Reiner Schlitzer

Keyword(s):

North Atlantic ◽

New Production ◽

Carbon Cycles ◽

The North ◽

The North Atlantic ◽

Organic Nutrients ◽

Particle Fluxes

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Longitudinal variability of organic nutrients in the North Atlantic subtropical gyre

Deep Sea Research Part I Oceanographic Research Papers ◽

10.1016/j.dsr.2015.11.009 ◽

2016 ◽

Vol 111 ◽

pp. 50-60 ◽

Cited By ~ 6

Author(s):

A. Landolfi ◽

H. Dietze ◽

G. Volpe

Keyword(s):

North Atlantic ◽

Subtropical Gyre ◽

The North ◽

The North Atlantic ◽

Organic Nutrients ◽

Longitudinal Variability

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Seasonal mean pressure reconstruction for the North Atlantic (1750–1850) based on early marine data

Climate of the Past ◽

10.5194/cp-1-19-2005 ◽

2005 ◽

Vol 1 (1) ◽

pp. 19-33 ◽

Cited By ~ 16

Author(s):

D. Gallego ◽

R. Garcia-Herrera ◽

P. Ribera ◽

P. D. Jones

Keyword(s):

North Atlantic ◽

Spatial Regression ◽

Regression Equations ◽

The North ◽

Best Response ◽

Mean Pressure ◽

Marine Data ◽

The North Atlantic ◽

Using Data ◽

Common Signal

Abstract. Measurements of wind strength and direction abstracted from European ships' logbooks during the recently finished CLIWOC project have been used to produce the first gridded Sea Level Pressure (SLP) reconstruction for the 1750–1850 period over the North Atlantic based solely on marine data. The reconstruction is based on a spatial regression analysis calibrated by using data taken from the ICOADS database. An objective methodology has been developed to select the optimal calibration period and spatial domain of the reconstruction by testing several thousands of possible models. The finally selected area, limited by the performance of the regression equations and by the availability of data, covers the region between 28° N and 52° N close to the European coast and between 28° N and 44° N in the open Ocean. The results provide a direct measure of the strength and extension of the Azores High during the 101 years of the study period. The comparison with the recent land-based SLP reconstruction by Luterbacher et al. (2002) indicates the presence of a common signal. The interannual variability of the CLIWOC reconstructions is rather high due to the current scarcity of abstracted wind data in the areas with best response in the regression. Guidelines are proposed to optimize the efficiency of future abstraction work.

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Estimating the age of juvenile loggerhead sea turtles in the North Atlantic

Canadian Journal of Zoology ◽

10.1139/z97-005 ◽

1997 ◽

Vol 75 (1) ◽

pp. 40-46 ◽

Cited By ~ 58

Author(s):

G. C. Hays ◽

R. Marsh

Keyword(s):

North Atlantic ◽

Sea Turtles ◽

Drift Time ◽

Loggerhead Sea Turtles ◽

The North ◽

The United Kingdom ◽

The North Atlantic ◽

Area North ◽

Using Data ◽

Nesting Beaches

Analysis of previously published records shows that the modal size of juvenile loggerhead sea turtles (Caretta caretta) found around the United Kingdom (the area north of 49°N and east of 12°W) is a carapace length of 20.5 cm. These turtles are believed to originate from nesting beaches in North America (principally Florida). We estimated their trans-Atlantic drift time using data from satellite-tracked buoys and from a mathematical model and, hence, estimated that the modal age of these juvenile turtles was between 1.80 and 3.75 years.

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Seasonal mean pressure reconstruction for the North Atlantic (1750–1850) based on early marine data

Climate of the Past Discussions ◽

10.5194/cpd-1-57-2005 ◽

2005 ◽

Vol 1 (1) ◽

pp. 57-92 ◽

Cited By ~ 1

Author(s):

D. Gallego ◽

R. Garcia-Herrera ◽

P. Ribera ◽

P. D. Jones

Keyword(s):

North Atlantic ◽

Spatial Regression ◽

Regression Equations ◽

The North ◽

Best Response ◽

Mean Pressure ◽

Marine Data ◽

The North Atlantic ◽

Using Data ◽

Common Signal

Abstract. Measures of wind strength and direction abstracted from European ships' logbooks during the recently finished CLIWOC project have been used to produce the first gridded Sea Level Pressure (SLP) reconstruction for the 1750-1850 period over the North Atlantic based solely on marine data. The reconstruction is based on a spatial regression analysis calibrated by using data taken from the ICOADS database. An objective methodology has been developed to select the optimal calibration period and spatial domain of the reconstruction by testing several thousands of possible models. The finally selected area, limited by the performance of the regression equations and by the availability of data, covers the region between 28°N and 52°N close to the European coast and between 28°N and 44°N in the open Ocean. The results provide a direct measure of the strength and extension of the Azores High during the 101 years of the study period. The comparison with the recent land-based SLP reconstruction by Luterbacher et al. (2002) indicates the presence of a common signal. The interannual variability of the CLIWOC reconstructions is rather high due to the current scarcity of abstracted wind data in the areas with best response in the regression. Guidelines are proposed to optimize the efficiency of future abstraction work.

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A late surviving Pliocene seal from high latitudes of the North Atlantic realm: the latest monachine seal on the southern margin of the North Sea

PeerJ ◽

10.7717/peerj.5734 ◽

2018 ◽

Vol 6 ◽

pp. e5734 ◽

Cited By ~ 1

Author(s):

Leonard Dewaele ◽

Olivier Lambert ◽

Stephen Louwye

Keyword(s):

North Sea ◽

North Atlantic ◽

Literature Study ◽

Late Pliocene ◽

The North ◽

The North Sea ◽

The North Atlantic ◽

The Mediterranean ◽

Using Data ◽

Monk Seals

Background The family of true seals, the Phocidae, is subdivided into two subfamilies: the southern Monachinae, and the northern Phocinae, following the subfamilies’ current distribution: extant Monachinae are largely restricted to the (sub-)Antarctic and the eastern Pacific, with historical distributions of the monk seals of the genus Monachus in the Caribbean, the Mediterranean and around Hawaii; and Phocinae to the northern temperate and Arctic zones. However, the fossil record shows that Monachinae were common in the North Atlantic realm during the late Miocene and early Pliocene. Until now, only one late Pliocene record is known from the Mediterranean, Pliophoca etrusca from Tuscany, Italy, but none from farther north in the North Atlantic. Methods We present the description of one partial phocid humerus collected in the early 20th century from the Antwerp area (Belgium), with an assessment of its stratigraphic origin using data from the literature. Results The studied humerus was recovered during construction works at the former Lefèvre dock in the Antwerp harbour (currently part of the America dock). Combining the information associated to the specimen with data from the literature and from local boreholes, the upper Pliocene Lillo Formation is ascertained as the lithological unit from which the specimen originates. Morphologically, among other features the shape of the deltopectoral crest and the poor development of the supinator crest indicates a monachine attribution for this specimen. The development of the deltopectoral crest is closer to the condition in extant Monachinae than in extinct Monachinae. Discussion The presented specimen most likely represents a monachine seal and a literature study clearly shows that it came from the latest early to late Pliocene Lillo Formation. This would be the first known monachine specimen from the latest early to late Pliocene of the North Sea, and more broadly from the northern part of the North Atlantic realm. This humerus differs from the humerus of P. etrusca and suggests a higher diversity of Monachinae in the latest early to late Pliocene than previously assumed.

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