Testing the metabolic hypothesis: temperature-dependent carbon cycling in the Eocene oceans

2014 ◽  
Vol 31 ◽  
pp. 171-172
Author(s):  
Paul N. Pearson
Keyword(s):  
Carbon Cycling ◽  
Temperature Dependent ◽  
Metabolic Hypothesis

Temperature-dependent remineralization and carbon cycling in the warm Eocene oceans

2014 ◽  
Vol 413 ◽  
pp. 158-166 ◽  
Author(s):  
Eleanor H. John ◽  
Jamie D. Wilson ◽  
Paul N. Pearson ◽  
Andy Ridgwell
Keyword(s):  
Carbon Cycling ◽  
Temperature Dependent

scholarly journals Calibration of key temperature-dependent ocean microbial processes in the cGENIE.muffin Earth system model

2020 ◽  
Author(s):  
Katherine Anne Crichton ◽  
Jamie Devereux Wilson ◽  
Andy Ridgwell ◽  
Paul N. Pearson
Keyword(s):  
Organic Matter ◽  
Carbon Cycling ◽  
Surface Waters ◽  
Numerical Models ◽  
Nutrient Supply ◽  
Earth System Model ◽  
System Model ◽  
Earth System ◽  
Temperature Dependent ◽  
Poc Export

Abstract. Temperature is a master parameter in the marine carbon cycle, exerting a critical control on the rate of biological transformation of a variety of solid and dissolved reactants and substrates. Although in the construction of numerical models of marine carbon cycling, temperature has been long-recognised as a key parameter in the production and export of organic matter at the ocean surface, it is much less commonly taken into account in the ocean interior. There, bacteria (primarily) transform sinking particulate organic matter into its dissolved constituents and thereby consume dissolved oxygen (and/or other electron acceptors such as sulphate) and release nutrients, which are then available for transport back to the surface. Here we present and calibrate a more complete temperature-dependent representation of marine carbon cycling in the cGENIE.muffin Earth system model, intended for both past and future climate applications. In this, we combine a temperature-dependent remineralisation scheme for sinking organic matter with a biological export production scheme that also includes a temperature-dependent limitation on nutrient uptake in surface waters (and hence phytoplankton growth). Via a parameter ensemble, we jointly calibrate the two parameterisations by statistically contrasting model projected fields of nutrients, oxygen, and the stable carbon isotopic signature (δ13C) of dissolved inorganic carbon in the ocean, with modern observations. We find that for the present-day, the temperature-dependent version shows as-good-as or better fit to data than the existing tuned non-temperature dependent version of the cGENIE.muffin. The main impact of adding temperature-dependent remineralisation is in driving higher rates of remineralisation in warmer waters and hence a more rapid return of nutrients to the surface there – stimulating organic matter production. As a result, more organic matter is exported below 80 m in mid and low latitude warmer waters as compared to the standard model. Conversely, at higher latitudes, colder water temperature reduces the rate of nutrient supply to the surface as a result of slower in-situ rates of remineralisation. We also assess the implications of including a more complete set of temperature-dependent parameterisations by analysing a series of historical transient experiments. We find that between the pre-industrial and the present day, in response to a simulated air temperature increase of 0.9 °C and ocean warming of 0.12 °C (0.6 °C in surface waters and 0.02 °C in deep waters), a reduction in POC export at 80 m of just 0.3 % occurs. In contrast, with no assumed temperature-dependent biological processes, global POC export at 80 m falls by 2.9 % between the pre-industrial and present day as a consequence of ocean stratification and reduced nutrient supply to the surface. This suggests that increased nutrient recycling in warmer conditions offsets some of the stratification-induced surface nutrient limitation in a warmer world, and that less carbon (and nutrients) then reaches the inner and deep ocean. This extension to the cGENIE.muffin Earth system model provides it with additional capabilities in addressing marine carbon cycling in warmer past and future worlds.

scholarly journals Calibration of temperature-dependent ocean microbial processes in the cGENIE.muffin (v0.9.13) Earth system model

2021 ◽  
Vol 14 (1) ◽  
pp. 125-149
Author(s):  
Katherine A. Crichton ◽  
Jamie D. Wilson ◽  
Andy Ridgwell ◽  
Paul N. Pearson
Keyword(s):  
Organic Matter ◽  
Carbon Cycling ◽  
System Model ◽  
Earth System ◽  
Temperature Dependent ◽  
Poc Export ◽  
Dependent Processes ◽  
Global Carbon ◽  
Atmospheric Pco2

Abstract. Temperature is a master parameter in the marine carbon cycle, exerting a critical control on the rate of biological transformation of a variety of solid and dissolved reactants and substrates. Although in the construction of numerical models of marine carbon cycling, temperature has been long recognised as a key parameter in the production and export of organic matter at the ocean surface, its role in the ocean interior is much less frequently accounted for. There, bacteria (primarily) transform sinking particulate organic matter (POM) into its dissolved constituents and consume dissolved oxygen (and/or other electron acceptors such as sulfate). The nutrients and carbon thereby released then become available for transport back to the surface, influencing biological productivity and atmospheric pCO2, respectively. Given the substantial changes in ocean temperature occurring in the past, as well as in light of current anthropogenic warming, appropriately accounting for the role of temperature in marine carbon cycling may be critical to correctly projecting changes in ocean deoxygenation and the strength of feedbacks on atmospheric pCO2. Here we extend and calibrate a temperature-dependent representation of marine carbon cycling in the cGENIE.muffin Earth system model, intended for both past and future climate applications. In this, we combine a temperature-dependent remineralisation scheme for sinking organic matter with a biological export production scheme that also includes a dependence on ambient seawater temperature. Via a parameter ensemble, we jointly calibrate the two parameterisations by statistically contrasting model-projected fields of nutrients, oxygen, and the stable carbon isotopic signature (δ13C) of dissolved inorganic carbon in the ocean with modern observations. We additionally explore the role of temperature in the creation and recycling of dissolved organic matter (DOM) and hence its impact on global carbon cycle dynamics. We find that for the present day, the temperature-dependent version shows a fit to the data that is as good as or better than the existing tuned non-temperature-dependent version of the cGENIE.muffin. The main impact of accounting for temperature-dependent remineralisation of POM is in driving higher rates of remineralisation in warmer waters, in turn driving a more rapid return of nutrients to the surface and thereby stimulating organic matter production. As a result, more POM is exported below 80 m but on average reaches shallower depths in middle- and low-latitude warmer waters compared to the standard model. Conversely, at higher latitudes, colder water temperature reduces the rate of nutrient resupply to the surface and POM reaches greater depth on average as a result of slower subsurface rates of remineralisation. Further adding temperature-dependent DOM processes changes this overall picture only a little, with a slight weakening of export production at higher latitudes. As an illustrative application of the new model configuration and calibration, we take the example of historical warming and briefly assess the implications for global carbon cycling of accounting for a more complete set of temperature-dependent processes in the ocean. We find that between the pre-industrial era (ca. 1700) and the present (year 2010), in response to a simulated air temperature increase of 0.9 ∘C and an associated projected mean ocean warming of 0.12 ∘C (0.6 ∘C in surface waters and 0.02 ∘C in deep waters), a reduction in particulate organic carbon (POC) export at 80 m of just 0.3 % occurs (or 0.7 % including a temperature-dependent DOM response). However, due to this increased recycling nearer the surface, the efficiency of the transfer of carbon away from the surface (at 80 m) to the deep ocean (at 1040 m) is reduced by 5 %. In contrast, with no assumed temperature-dependent processes impacting production or remineralisation of either POM or DOM, global POC export at 80 m falls by 2.9 % between the pre-industrial era and the present day as a consequence of ocean stratification and reduced nutrient resupply to the surface. Our analysis suggests that increased temperature-dependent nutrient recycling in the upper ocean has offset much of the stratification-induced restriction in its physical transport.

(111) Monocrystalline Nickel Films

1972 ◽  
Vol 30 ◽  
pp. 512-513
Author(s):  
T.E. Pratt ◽  
R.W. Vook
Keyword(s):  
Film Thickness ◽  
Deposition Rate ◽  
Room Temperature ◽  
Narrow Range ◽  
High Vacuum ◽  
Residual Pressure ◽  
Temperature Dependent ◽  
Deposition Parameters ◽  
Transmission Electron ◽  
Substrate Temperatures

(111) oriented thin monocrystalline Ni films have been prepared by vacuum evaporation and examined by transmission electron microscopy and electron diffraction. In high vacuum, at room temperature, a layer of NaCl was first evaporated onto a freshly air-cleaved muscovite substrate clamped to a copper block with attached heater and thermocouple. Then, at various substrate temperatures, with other parameters held within a narrow range, Ni was evaporated from a tungsten filament. It had been shown previously that similar procedures would yield monocrystalline films of CU, Ag, and Au.For the films examined with respect to temperature dependent effects, typical deposition parameters were: Ni film thickness, 500-800 A; Ni deposition rate, 10 A/sec.; residual pressure, 10-6 torr; NaCl film thickness, 250 A; and NaCl deposition rate, 10 A/sec. Some additional evaporations involved higher deposition rates and lower film thicknesses.Monocrystalline films were obtained with substrate temperatures above 500° C. Below 450° C, the films were polycrystalline with a strong (111) preferred orientation.

In Vitro Effects of Urokinase — Prevention by Different Inhibitors

1990 ◽  
Vol 64 (03) ◽  
pp. 402-406 ◽  
Author(s):  
M D Oethinger ◽  
E Seifried
Keyword(s):  
In Vitro Study ◽  
Thrombin Time ◽  
Plasma Samples ◽  
Temperature Dependent ◽  
Chloromethyl Ketone ◽  
Control Value ◽  
Dose Time ◽  
In Vitro Effects ◽  
Full Protection

SummaryThe present in vitro study investigated dose-, time- and temperature-dependent effects of two-chain urokinase plasminogen activato(u-PA, urokinase) on normal citrated plasma. When 10 μg/ml u-PA wereadded to pooled normal plasma and incubated for 30 min at an ambient temperature (25° C), α2-antiplas-min decreased to 8% of the control value. Incubation on ice yielded a decrease to 45% of control,whereas α2-antiplasmin was fully consumed at 37° C. Fibrinogen and plasminogen fell to 46% and 39%, respectively, after a 30 min incubation at 25° C. Thrombin time prolonged to 190% of control.Various inhibitors were studied with respect to their suitability and efficacy to prevent these in vitro effects. Aprotinin exhibited a good protective effect on fibrinogen at concentrations exceeding 500 KlU/ml plasma. Its use, however, was limited due to interferences with some haemostatic assays. We could demonstrate that L-Glutamyl-L-Glycyl-L-Arginyl chloromethyl ketone (GGACK) and a specific polyclonal anti-u-PA-antibody (anti-u-PA-IgG) effectively inhibited urokinase-induced plasmin generation without interfering with haemostatic assays. The anti-u-PA-antibody afforded full protection ofα2-antiplasmin at therapeutic levels of u-PA.It is concluded that u-PA in plasma samples from patients during thrombolytic therapy may induce in vitro effects which should be prevented by the use of a suitable inhibitor such as GGACK or specific anti-u-PA-antibody.

Interventional Thermal Injury of the Arterial Wall: Unfolding of von Willebrand Factor and Its Increased Binding to Collagen after 55° C Heating

1996 ◽  
Vol 75 (03) ◽  
pp. 515-519 ◽  
Author(s):  
Mark J Post ◽  
Anke N de Graaf-Bos ◽  
George Posthuma ◽  
Philip G de Groot ◽  
Jan J Sixma ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Conformational Changes ◽  
Arterial Wall ◽  
Platelet Adhesion ◽  
Type I ◽  
Temperature Dependent ◽  
Collagen Types ◽  
Electron Microscopic ◽  
Von Willebrand ◽  
Willebrand Factor

Summary Purpose. Thermal angioplasty alters the thrombogenicity of the arterial wall. In previous studies, platelet adhesion was found to increase after heating human subendothelium to 55° C and decrease after heating to 90° C. In the present electron microscopic study, the mechanism of this temperature-dependent platelet adhesion to the heated arterial wall is elucidated by investigating temperature-dependent conformational changes of von Willebrand factor (vWF) and collagen types I and III and the binding of vWF to heated collagen. Methods. Purified vWF and/or collagen was applied to electron microscopic grids and heated by floating on a salt-solution of 37° C, 55° C or 90° C for 15 s. After incubation with a polyclonal antibody against vWF and incubation with protein A/gold, the grids were examined by electron microscopy. Results. At 37° C, vWF was coiled. At 55° C, vWF unfolded, whereas heating at 90° C caused a reduction in antigenicity. Collagen fibers heated to 37° C were 60.3 ± 3.1 nm wide. Heating to 55° C resulted in the unwinding of the fibers, increasing the width to 87.5 ± 8.2 nm (p < 0.01). Heating to 90° C resulted in denatured fibers with an enlarged width of 85.1 ± 6.1 nm (p < 0.05). Heating of collagen to 55° C resulted in an increased vWF binding as compared to collagen heated to 37° C or to 90° C. Incubation of collagen with vWF, prior to heating, resulted in a vWF binding after heating to 55° C that was similar to the 37° C binding and a decreased binding after 90° C. Conclusions. After 55° C heating, the von Willebrand factor molecule unfolds and collagen types I and III exhibit an increased adhesiveness for von Willebrand factor. Heating to 90° C denatures von Willebrand factor and collagen. The conformation changes of von Willebrand factor and its altered binding to collagen type I and III may explain the increased and decreased platelet adhesion to subendothelium after 55° C and 90° C heating, respectively.

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