Nitrogen circulation in the water column in the Oyashio region with reference to its high productivity

1991 ◽  
Vol 47 (6) ◽  
pp. 265-275 ◽  
Author(s):  
Yasuo Matsukawa ◽  
Katsuyuki Sasaki
Keyword(s):  
Water Column ◽  
High Productivity ◽  
Oyashio Region

scholarly journals Peru upwelling plankton respiration: calculations of carbon flux, nutrient retention efficiency and heterotrophic energy production

2014 ◽  
Vol 11 (11) ◽  
pp. 16177-16206 ◽  
Author(s):  
T. T. Packard ◽  
N. Osma ◽  
I. Fernández-Urruzola ◽  
L. A. Codispoti ◽  
J. P. Christensen ◽  
...  
Keyword(s):  
Water Column ◽  
Depth Profile ◽  
Carbon Flux ◽  
Energy Production ◽  
Nutrient Retention ◽  
Euphotic Zone ◽  
Nutrient Regeneration ◽  
Retention Efficiency ◽  
High Productivity ◽  
Water Column Respiration

Abstract. Oceanic depth profiles of plankton respiration are described by a power function, RCO2 = (RCO2)0(z/z0)b similar to the vertical carbon flux profile. Furthermore, because both ocean processes are closely related, conceptually and mathematically, each can be calculated from the other. The exponent (b), always negative, defines the maximum curvature of the respiration depth-profile and controls the carbon flux. When b is large, the C flux (FC) from the epipelagic ocean is low and the nutrient retention efficiency (NRE) is high allowing these waters to maintain high productivity. The opposite occurs when b is small. This means that the attenuation of respiration in ocean water columns is critical in understanding and predicting both vertical FC as well as the capacity of epipelagic ecosystems to retain their nutrients. The NRE is a new metric defined as the ratio of nutrient regeneration in a seawater layer to the nutrients introduced into that layer via FC. A depth-profile of FC is the integral of water column respiration. This relationship facilitates calculating ocean sections of FC from water column respiration. In a FC section across the Peru upwelling system we found a FC maximum extending down to 400 m, 50 km off the Peru coast. Finally, coupling respiratory electron transport system activity to heterotrophic oxidative phosphorylation promoted the calculation of an ocean section of heterotrophic energy production (HEP). It ranged from 250 to 500 J d−1 m−3 in the euphotic zone, to less than 5 J d−1 m−3 below 200 m on this ocean section.

Monsoon variability during Mid Pliocene Warm Period: Evidence from oceanic denitrification at eastern Arabian Sea

2021 ◽  
Author(s):  
Padmasini Behera ◽  
Manish Tiwari
Keyword(s):  
Organic Matter ◽  
Surface Water ◽  
Water Column ◽  
Arabian Sea ◽  
Water Productivity ◽  
Warm Period ◽  
Late Pliocene ◽  
High Productivity ◽  
Future Global Warming ◽  
Eastern Arabian Sea

<p>The variability of the South Asian Monsoon (SoAM) in warmer climatic conditions is not established yet. The Mid-Pliocene Warm Period (MPWP, 3.264 to 3.025 ma) is the most recent such event when the boundary conditions were similar to present with similar CO<sub>2</sub> concentration (more than 400 ppmv) and temperature (2-3°C higher than present). It presents the best analogue for understanding the impacts of future global warming on SoAM. The high-resolution study of denitrification from the eastern Arabian Sea can provide an insight into the SoAM variability during MPWP. Denitrification is the process by which nitrate is reduced to nitrogen gas (N<sub>2</sub> or N<sub>2</sub>O) during organic matter decay in oxygen minima zones in the water column. The denitrification process enriches the nitrate pool with <sup>15</sup>N, which is incorporated in the particulate organic matter. Denitrification is governed by the surface water productivity related to SoAM strength and the water column ventilation. We analyzed the nitrogen isotopic ratio of sedimentary organic matter (SOM, δ<sup>15</sup>N<sub>SOM</sub>) to examine the denitrification in the eastern Arabian Sea. Total nitrogen (TN %) and total organic carbon (TOC%) are used to estimate the surface water productivity from the sediment collected during expedition IODP 355, Hole U1456A. We find that the δ<sup>15</sup>N<sub>SOM</sub> values vary between 7-9 ‰ during 3.22-3.15 Ma and 2.9-2.75 Ma indicating high denitrification. High δ<sup>15</sup>N<sub>SOM</sub> values coincide with high productivity as shown by both TN and TOC. It shows two major periods in the late Pliocene (3.22-3.15 Ma and 2.92-2.75 Ma) associated with stronger denitrification and high productivity. These results indicate the intensification of SoAM during warmer periods of Late Pliocene and at the start of intensification of Northern hemisphere glaciation. The enhanced denitrification during this period could possibly be due to a reduction in deep water ventilation and monsoon driven upsurge in productivity.</p>

scholarly journals Peruvian upwelling plankton respiration: calculations of carbon flux, nutrient retention efficiency, and heterotrophic energy production

2015 ◽  
Vol 12 (9) ◽  
pp. 2641-2654 ◽  
Author(s):  
T. T. Packard ◽  
N. Osma ◽  
I. Fernández-Urruzola ◽  
L. A. Codispoti ◽  
J. P. Christensen ◽  
...  
Keyword(s):  
Water Column ◽  
Depth Profile ◽  
Carbon Flux ◽  
Energy Production ◽  
Nutrient Retention ◽  
Euphotic Zone ◽  
Nutrient Regeneration ◽  
Retention Efficiency ◽  
High Productivity ◽  
Water Column Respiration

Abstract. Oceanic depth profiles of plankton respiration are described by a power function, RCO2 = (RCO2)0 (z/z0)b, similar to the vertical carbon flux profile. Furthermore, because both ocean processes are closely related, conceptually and mathematically, each can be calculated from the other. The exponent b, always negative, defines the maximum curvature of the respiration–depth profile and controls the carbon flux. When |b| is large, the carbon flux (FC) from the epipelagic ocean is low and the nutrient retention efficiency (NRE) is high, allowing these waters to maintain high productivity. The opposite occurs when |b| is small. This means that the attenuation of respiration in ocean water columns is critical in understanding and predicting both vertical FC as well as the capacity of epipelagic ecosystems to retain their nutrients. The ratio of seawater RCO2 to incoming FC is the NRE, a new metric that represents nutrient regeneration in a seawater layer in reference to the nutrients introduced into that layer via FC. A depth profile of FC is the integral of water column respiration. This relationship facilitates calculating ocean sections of FC from water column respiration. In an FC section and in a NRE section across the Peruvian upwelling system we found an FC maximum and a NRE minimum extending down to 400 m, 50 km off the Peruvian coast over the upper part of the continental slope. Finally, considering the coupling between respiratory electron transport system activity and heterotrophic oxidative phosphorylation promoted the calculation of an ocean section of heterotrophic energy production (HEP). It ranged from 250 to 500 J d−1 m−3 in the euphotic zone to less than 5 J d−1 m−3 below 200 m on this ocean section.

scholarly journals Sequential nutrient uptake as a potential mechanism for phytoplankton to maintain high primary productivity and balanced nutrient stoichiometry

2017 ◽  
Vol 14 (9) ◽  
pp. 2469-2480 ◽  
Author(s):  
Kedong Yin ◽  
Hao Liu ◽  
Paul J. Harrison
Keyword(s):  
Nutrient Uptake ◽  
Water Column ◽  
Primary Productivity ◽  
Nutrient Ratios ◽  
Vertical Profiles ◽  
Nutrient Stoichiometry ◽  
High Productivity ◽  
Limiting Nutrients ◽  
Limiting Nutrient

Abstract. We hypothesize that phytoplankton have the sequential nutrient uptake strategy to maintain nutrient stoichiometry and high primary productivity in the water column. According to this hypothesis, phytoplankton take up the most limiting nutrient first until depletion, continue to draw down non-limiting nutrients and then take up the most limiting nutrient rapidly when it is available. These processes would result in the variation of ambient nutrient ratios in the water column around the Redfield ratio. We used high-resolution continuous vertical profiles of nutrients, nutrient ratios and on-board ship incubation experiments to test this hypothesis in the Strait of Georgia. At the surface in summer, ambient NO3− was depleted with excess PO43− and SiO4− remaining, and as a result, both N : P and N : Si ratios were low. The two ratios increased to about 10 : 1 and 0. 45 : 1, respectively, at 20 m. Time series of vertical profiles showed that the leftover PO43− continued to be removed, resulting in additional phosphorus storage by phytoplankton. The N : P ratios at the nutricline in vertical profiles responded differently to mixing events. Field incubation of seawater samples also demonstrated the sequential uptake of NO3− (the most limiting nutrient) and then PO43− and SiO4− (the non-limiting nutrients). This sequential uptake strategy allows phytoplankton to acquire additional cellular phosphorus and silicon when they are available and wait for nitrogen to become available through frequent mixing of NO3− (or pulsed regenerated NH4). Thus, phytoplankton are able to maintain high productivity and balance nutrient stoichiometry by taking advantage of vigorous mixing regimes with the capacity of the stoichiometric plasticity. To our knowledge, this is the first study to show the in situ dynamics of continuous vertical profiles of N : P and N : Si ratios, which can provide insight into the in situ dynamics of nutrient stoichiometry in the water column and the inference of the transient status of phytoplankton nutrient stoichiometry in the coastal ocean.

scholarly journals Comparison of modern and fossil diatom assemblages and their implication on sea-ice conditions in coastal Antarctic region

MAUSAM ◽  
2021 ◽  
Vol 62 (4) ◽  
pp. 659-664
Author(s):  
SUNILKUMAR SHUKLA ◽  
M. SUDHAKAR
Keyword(s):  
Sea Ice ◽  
Water Column ◽  
Abundant Species ◽  
Diatom Assemblages ◽  
Coastal Regions ◽  
Antarctic Region ◽  
Overlying Water ◽  
Sea Ice Extent ◽  
High Productivity ◽  
Ice Conditions

Antarctic Coastal regions are thought to be characterized by high productivity usually dominated by diatoms. Considering their prime importance in global carbon biological pump, diatom distribution and abundance studies are sparse especially in coastal regions of Antarctica. Biogenic silica is considered to be severely affected by dissolution in the undersaturated ocean water, therefore, combined study of diatom assemblages from water column and those found in the sediments is important. Therefore, we conducted a combined study of sediment diatoms along with surface water diatoms collected from Coastal Antarctica. When the modern assemblages are compared to the fossil record, it is clear the most of the important diatoms from the summer assemblages are not preserved in the underlying sediments. The studies reveal that only F. kerguelensis is common abundant species in both water and sediment which suggests that coastal Antarctic region could be having more open ocean influence. In contrast, the presence of sea ice related diatom species from surface sediment indicate for expansion of sea ice or ice edge adjacent to the water column, however such species were not found in the overlying water samples which could be due to less sea-ice extent.

scholarly journals Sequential Nutrient Uptake by Phytoplankton Maintains High Primary Productivity and Balanced Nutrient Stoichiometry

2016 ◽  
Author(s):  
Kedong Yin ◽  
Paul J. Harrison
Keyword(s):  
Nutrient Uptake ◽  
Water Column ◽  
Primary Productivity ◽  
Nutrient Ratios ◽  
Vertical Profiles ◽  
Nutrient Stoichiometry ◽  
High Productivity ◽  
Limiting Nutrients ◽  
Limiting Nutrient ◽  
Nutrient Profiles

Abstract. We hypothesize that phytoplankton have the sequential nutrient uptake strategy in order to maintain nutrient stoichiometry and high primary productivity in the water column. Nutrient limited phytoplankton are capable of taking up the limiting nutrient first and they take up non-limiting nutrients when the limiting nutrient debt has been overcome. We used high resolution continuous vertical profiles of nutrients, nutrient ratios and on-board ship incubation experiments to test this hypothesis in the Strait of Georgia. At the surface in summer, ambient nitrate was depleted with excess phosphate and silicate remaining, and as a result, both N : P and N : Si ratios were low. The two ratios increased to about 10 : 1 and 0.45 : 1, respectively, at 20 m. Time series of vertical profiles showed that the leftover phosphate continued to be removed, resulting in additional phosphorus storage by phytoplankton. There were various shapes of vertical profiles of N : P and at the nutricline it changed quickly in response to mixing events. A field incubation of seawater also demonstrated the sequential uptake of nitrate (the most limiting nutrient) and then phosphate and silicate (the non-limiting nutrients). This sequential uptake strategy allows phytoplankton to acquire additional cellular phosphorus and silicon when they are available and wait for nitrogen to become available through frequent mixing of nitrate (or pulsed regenerated ammonium). Thus, phytoplankton show variability of nutrient stoichiometry and are capable of maintaining high productivity by taking advantage of vigorous mixing regimes. To our knowledge, this is the first study to show the dynamics of continuous vertical profiles of N : P and N : Si ratios and to examine the responses of phytoplankton to nutrients supplied naturally by mixing events. The continuous nutrient profiles provided insight into the in situ dynamics of nutrient stoichiometry in the water column and the transient status of nutrient stoichiometry of phytoplankton in the field.

A modern technique for high productivity cold forging

1962 ◽  
Vol 41 (9) ◽  
pp. 552 ◽  
Author(s):  
R. Hayward ◽  
P.J. Mullins
Keyword(s):  
Cold Forging ◽  
High Productivity ◽  
Modern Technique

Changing the face of short fiber –a review of the eucalyptus revolution

TAPPI Journal ◽  
2015 ◽  
Vol 14 (6) ◽  
pp. 353-359 ◽  
Author(s):  
PETER W. HART ◽  
RICARDO B. SANTOS
Keyword(s):  
Fossil Fuels ◽  
Wood Quality ◽  
Short Fiber ◽  
Fiber Volume ◽  
Private Industry ◽  
High Productivity ◽  
Paper Manufacturing ◽  
Short Rotation ◽  
Eucalypt Plantations ◽  
Eucalyptus Plantations

Eucalyptus plantations have been used as a source of short fiber for papermaking for more than 40 years. The development in genetic improvement and clonal programs has produced improved density plantations that have resulted in fast growing, increased fiber volume eucalypts becoming the most widely used source of short fibers in the world. High productivity and short rotation times, along with the uniformity and improved wood quality of clonal plantations have attracted private industry investment in eucalypt plantations. Currently, only a handful of species or hybrids are used in plantation efforts. Many more species are being evaluated to either enhance fiber properties or expand the range of eucalypt plantations. Eucalyptus plantations are frequently planted on nonforested land and may be used, in part, as a means of conserving native forests while allowing the production of high quality fiber for economic uses. Finally, eucalypt plantations can provide significant carbon sinks, which may be used to help offset the carbon released from burning fossil fuels. The development and expansion of eucalypt plantations represents a substantial revolution in pulp and paper manufacturing.

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