scholarly journals Marine Phytoplankton Stoichiometry Mediates Nonlinear Interactions Between Nutrient Supply, Temperature, and Atmospheric CO<sub>2</sub>

2017 ◽  
Author(s):  
Allison R. Moreno ◽  
George I. Hagstrom ◽  
Francois W. Primeau ◽  
Simon A. Levin ◽  
Adam C. Martiny
Keyword(s):  
Carbon Cycling ◽  
Ocean Circulation ◽  
Negative Relationship ◽  
Nutrient Supply ◽  
Marine Phytoplankton ◽  
Phosphorus Concentration ◽  
Biological Pump ◽  
Carbon Export ◽  
Environmental Model ◽  
The Impact

Abstract. Marine phytoplankton stoichiometry links nutrient supply to marine carbon export. Deviations of phytoplankton stoichiometry from Redfield proportions (106C : 1P) could therefore have a significant impact on carbon cycling, and understanding which environmental factors drive these deviations may reveal new mechanisms that regulate the carbon cycle. To explore the links between environmental conditions, stoichiometry, and carbon cycling, we compared four different models for variations in phytoplankton C : P: a fixed Redfield model, a model with C : P given as a function of surface phosphorus concentration ([P]), a model with C : P given as a function of temperature, and a new multi-environmental model that predicts C : P as a function of light, temperature, and [P]. These stoichiometric models were embedded into a box model of the ocean circulation, which resolves the three major ocean biomes (high-latitude, subtropical gyres, and iron-limited tropical upwelling regions). Contrary to the expectation of a monotonic relationship between surface nutrient drawdown and carbon export, we found that lateral nutrient transport from lower C : P tropical waters to high C : P subtropical waters could cause carbon-export to decrease with increased tropical nutrient utilization. Temperature is thought to be one of the primary drivers of changes in atmospheric pCO2 (pCO2,atm) across glacial/interglacial periods, and it has been hypothesized that a positive feedback between temperature and pCO2,atm will play an important role in anthropogenic climate change, with changes in the biological pump playing at most a secondary role. Here we show that environmentally driven shifts in stoichiometry make the biological pump more influential, and may reverse the expected negative relationship between temperature and pCO2,atm. In the temperature-only model changes in tropical temperature have more impact on the Δ pCO2,atm (~ 41 ppm) compared to subtropical temperature (~ 4.5 ppm). Our multi-environmental model produced a decline in pCO2,atm of ~ 46 when temperature spanned a change of 10 °C. Thus, we find that variation in marine phytoplankton stoichiometry and its environmental controlling factor can lead to counterintuitive controls on pCO2,atm, suggesting the need for further studies of ocean C : P and the impact on ocean carbon cycling.

scholarly journals Marine phytoplankton stoichiometry mediates nonlinear interactions between nutrient supply, temperature, and atmospheric CO<sub>2</sub>

2018 ◽  
Vol 15 (9) ◽  
pp. 2761-2779 ◽  
Author(s):  
Allison R. Moreno ◽  
George I. Hagstrom ◽  
Francois W. Primeau ◽  
Simon A. Levin ◽  
Adam C. Martiny
Keyword(s):  
Carbon Cycling ◽  
Ocean Circulation ◽  
Circulation Model ◽  
Nutrient Supply ◽  
Marine Phytoplankton ◽  
Phosphorus Concentration ◽  
Biological Pump ◽  
Carbon Export ◽  
Environmental Model ◽  
The Impact

Abstract. Marine phytoplankton stoichiometry links nutrient supply to marine carbon export. Deviations of phytoplankton stoichiometry from Redfield proportions (106C : 1P) could therefore have a significant impact on carbon cycling, and understanding which environmental factors drive these deviations may reveal new mechanisms regulating the carbon cycle. To explore the links between environmental conditions, stoichiometry, and carbon cycling, we compared four different models of phytoplankton C : P: a fixed Redfield model, a model with C : P given as a function of surface phosphorus concentration (P), a model with C   P given as a function of temperature, and a new multi-environmental model that predicts C : P as a function of light, temperature, and P. These stoichiometric models were embedded into a five-box ocean circulation model, which resolves the three major ocean biomes (high-latitude, subtropical gyres, and tropical upwelling regions). Contrary to the expectation of a monotonic relationship between surface nutrient drawdown and carbon export, we found that lateral nutrient transport from lower C : P tropical waters to high C : P subtropical waters could cause carbon export to decrease with increased tropical nutrient utilization. It has been hypothesized that a positive feedback between temperature and pCO2, atm will play an important role in anthropogenic climate change, with changes in the biological pump playing at most a secondary role. Here we show that environmentally driven shifts in stoichiometry make the biological pump more influential, and may reverse the expected positive relationship between temperature and pCO2, atm. In the temperature-only model, changes in tropical temperature have more impact on the Δ pCO2, atm (∼ 41 ppm) compared to subtropical temperature changes (∼ 4.5 ppm). Our multi-environmental model predicted a decline in pCO2, atm of ∼ 46 ppm when temperature spanned a change of 10 °C. Thus, we find that variation in marine phytoplankton stoichiometry and its environmental controlling factors can lead to nonlinear controls on pCO2, atm, suggesting the need for further studies of ocean C : P and the impact on ocean carbon cycling.

scholarly journals The recovery of the biological pump across the K/Pg boundary in the GSSP of El Kef, Tunisia

2021 ◽  
Author(s):  
Joep van Dijk ◽  
Julio Sepúlveda ◽  
Laia Alegret ◽  
Heather Birch ◽  
Timothy Bralower ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Carbon Fixation ◽  
Open Ocean ◽  
Marine Phytoplankton ◽  
Outer Shelf ◽  
Biological Pump ◽  
Mass Extinctions ◽  
Physiological Models ◽  
El Kef ◽  
The Impact

&lt;p&gt;The study of Earth&amp;#8217;s Big Five mass extinctions provides insight into the resilience of ecosystems to environmental perturbations. Earth&amp;#8217;s most recent mass extinction at the Cretaceous/Paleogene boundary (K/Pg) was caused by the impact of an asteroid in the Yucatan peninsula rather than by intense volcanism. Mass extinctions among marine calcareous nannoplankton heavily disrupted the marine food web resulting in a severe weakening of the ocean&amp;#8217;s biological pump. The timing and heterogeneous nature of the recovery of the biological pump remain poorly resolved in the neritic zone in the aftermath of the impact. Here, we address the evolution of the biological pump across the K/Pg at the Global Boundary Stratotype Section (GSSP) at El Kef, Tunisia using high-resolution compound-specific carbon isotope records (&lt;em&gt;&amp;#948;&lt;/em&gt;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;biomarker&lt;/sub&gt;) of non-calcareous marine phototrophs from an outer shelf to upper bathyal setting of the southwestern Tethys Ocean. We use &lt;em&gt;&amp;#948;&lt;/em&gt;&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;biomarker&lt;/sub&gt; to reconstruct &amp;#949;&lt;sub&gt;p&lt;/sub&gt;, which is a function of the community structure of marine phototrophs, their rate of carbon fixation, and the concentration and isotopic composition of aqueous CO&lt;sub&gt;2&lt;/sub&gt;. We then use our &lt;em&gt;&amp;#949;&lt;/em&gt;&lt;sub&gt;p&lt;/sub&gt; record to constrain the recovery of the biological pump in this region while considering the composition of marine phytoplankton, the assemblage and isotopic composition of benthic foraminifera, state-of-the-art physiological models for &lt;em&gt;&amp;#949;&lt;/em&gt;&lt;sub&gt;p&lt;/sub&gt;, and carbon cycle simulations using cGENIE. Our results indicate that the recovery of the biological pump in the outer shelf-upper bathyal zone likely outpaced the recovery in the open ocean. This is in agreement with the selective extinctions among phytoplankton at the K/Pg, with most survivors that would later repopulate open-ocean sites being adapted to neritic environments.&lt;/p&gt;

Dampak Kebijakan Moneter Pada Output Di Negara-Negara ASEAN Tahun 1980-2014

2017 ◽  
Vol 4 (1) ◽  
pp. 58-70
Author(s):  
Nur Widiastuti
Keyword(s):  
Monetary Policy ◽  
Interest Rate ◽  
Fixed Effects ◽  
Empirical Studies ◽  
Negative Relationship ◽  
Least Square ◽  
Fixed Effects Model ◽  
State Data ◽  
Ordinary Least Square ◽  
The Impact

The Impact of monetary Policy on Ouput is an ambiguous. The results of previous empirical studies indicate that the impact can be a positive or negative relationship. The purpose of this study is to investigate the impact of monetary policy on Output more detail. The variables to estimatate monetery poicy are used state and board interest rate andrate. This research is conducted by Ordinary Least Square or Instrumental Variabel, method for 5 countries ASEAN. The state data are estimated for the period of 1980 – 2014. Based on the results, it can be concluded that the impact of monetary policy on Output shown are varied.Keyword: Monetary Policy, Output, Panel Data, Fixed Effects Model

Risk Attitude and Corporate Investment under Output Market Uncertainty: Evidence from The Mekong River Delta, Vietnam

2016 ◽  
pp. 59-70
Author(s):  
Ninh Le Khuong ◽  
Nghiem Le Tan ◽  
Tho Huynh Huu
Keyword(s):  
Negative Relationship ◽  
Risk Attitude ◽  
Business Strategies ◽  
Risk Averse ◽  
Market Uncertainty ◽  
Firm Investment ◽  
Output Market ◽  
The Impact ◽  
The Relationship

This paper aims to detect the impact of firm managers’ risk attitude on the relationship between the degree of output market uncertainty and firm investment. The findings show that there is a negative relationship between these two aspects for risk-averse managers while there is a positive relationship for risk-loving ones, since they have different utility functions. Based on the findings, this paper proposes recommendations for firm managers to take into account when making investment decisions and long-term business strategies as well.

Comparing the Impact of Religious Discourse on HIV/AIDS in Islam and Christianity in Africa

2012 ◽  
Vol 8 ◽  
Author(s):  
Sloane Speakman
Keyword(s):  
Social Factors ◽  
Negative Relationship ◽  
Hiv Prevalence ◽  
Religious Discourse ◽  
Prevalence Rates ◽  
The Social ◽  
High Prevalence ◽  
Islam And Christianity ◽  
Sub Saharan ◽  
The Impact

In examining the strikingly high prevalence rates of HIV in many parts of Africa, reaching as high as 5% in some areas, how does the discourse promoted by the predominant religions across the continent, Islam and Christianity, affect the outlook of their followers on the epidemic? This question becomes even more intriguing after discovering the dramatic difference in rate of HIV prevalence between Muslims and Christians in Africa, confirmed by studies that have found a negative relationship to exist between HIV prevalence and being Muslim in Africa, even in Sub-Saharan African nations. Why does this gap in prevalence rates exist? Does Islam advocate participating in less risky behavior more so than Christianity? By comparing the social construction, epidemiological understanding and public responses among Muslim populations in Africa with Christian ones, it becomes apparent that many similarities exist between the two regarding discourse and that, rather than religious discourse itself, other social factors, such as circumcision practices, contribute more to the disparity in HIV prevalence than originally thought.

Globalization, Poverty, Environmental Degradation and Economic Growth Nexus: Empirical Analysis of SAARC Regions

2020 ◽  
Vol 39 (1) ◽  
Author(s):  
Adiqa Kiani ◽  
Ejaz Ullah ◽  
Khair Muhammad
Keyword(s):  
Economic Growth ◽  
Sri Lanka ◽  
Empirical Analysis ◽  
Environmental Degradation ◽  
Negative Relationship ◽  
Policy Makers ◽  
Significant Negative Relationship ◽  
The Impact

The main objective of this study is to investigate the impact of poverty, globalization, and environmental degradation on economic growth in the selected SAARC countries. This study is employed panel Autoregressive Distributive Lag (ARDL) technique for empirical analysis using selected SAARC regions including India, Pakistan, Bangladesh, Nepal and Sri Lanka over the period of 1980 to 2018. Globalization impacts economic growth positively and significantly.  In addition to this the significant negative relationship is found between population and economic growth. The results show that poverty is positively related with environmental degradation. Furthermore, the results indicate that globalization is positively and significantly associated with environmental degradation in the SAARC region. Finally, the results show that urbanization is positive and significantly associated with environmental degradation, which could be the serious concerns for the policy makers to control.

Measuring Effectiveness Of Economic Growth On Reducing Infant Mortality Rate In Tamilnadu

2019 ◽  
Vol 118 (4) ◽  
pp. 129-141
Author(s):  
Mr. Y. EBENEZER
Keyword(s):  
Economic Growth ◽  
Mortality Rate ◽  
Infant Mortality ◽  
Negative Relationship ◽  
Infant Mortality Rate ◽  
Domestic Product ◽  
Per Capita ◽  
The Impact ◽  
Adf Test ◽  
Bound Test

                   This paper deals with economic growth and infant mortality rate in Tamilnadu. The objects of this paper are to test the relationship between Per capita Net State Domestic Product and infant mortality rate and also to measure the impact of Per capita Net State Domestic Product on infant mortality rate in Tamil Nadu. This analysis has employed the ADF test and ARDL approach. The result of the study shows that IMR got reduced and Per capita Net State Domestic Product increased during the study period. This analysis also revealed that there is a negative relationship between IMR and the economic growth of Tamilnadu. In addition, ARDL bound test result has concluded that per capita Net State Domestic Product of Tamilnadu has long run association with IMR.

The Impact of Oil Price Fluctuations on Industry Stock Returns: Evidence from International Markets

2018 ◽  
Vol 5 (1) ◽  
pp. 1-12
Author(s):  
Elias Randjbaran ◽  
Reza Tahmoorespour ◽  
Marjan Rezvani ◽  
Meysam Safari
Keyword(s):  
Stock Returns ◽  
Oil And Gas ◽  
Negative Relationship ◽  
The United States ◽  
Oil Price ◽  
Price Variation ◽  
Price Changes ◽  
Price Fluctuations ◽  
Food And Beverage ◽  
The Impact

This study investigates the impact of oil price variation on 14 industries in six markets, including Canada, China, France, India, the United Kingdom, and the United States. Panel weekly data were collected from June 1998 to December 2011. The results indicate that price fluctuations primarily affect the Oil and Gas as well as the Mining industries and have the least influence on the Food and Beverage industry. Furthermore, in three out of six of these countries (Canada, France, and the U.K.), oil price changes negatively affect the Pharmaceutical and Biotechnology industry. One possible reason for the negative relationship between oil price changes and the Pharmaceutical and Biotechnology industries in the above-mentioned countries is that the governments of these countries fund their healthcare systems. Portfolio managers and investors will find the results of this study useful because it enables adjusting portfolios based on knowledge of the industries that are impacted the most or the least by oil price fluctuations.

On the impact of sea ice in a global ocean circulation model

1997 ◽  
Vol 25 ◽  
pp. 111-115 ◽  
Author(s):  
Achim Stössel
Keyword(s):  
Southern Ocean ◽  
Sea Ice ◽  
Ocean Circulation ◽  
General Circulation ◽  
Thermohaline Circulation ◽  
Circulation Model ◽  
Deep Ocean ◽  
Global Ocean ◽  
Convective Activity ◽  
The Impact

This paper investigates the long-term impact of sea ice on global climate using a global sea-ice–ocean general circulation model (OGCM). The sea-ice component involves state-of-the-art dynamics; the ocean component consists of a 3.5° × 3.5° × 11 layer primitive-equation model. Depending on the physical description of sea ice, significant changes are detected in the convective activity, in the hydrographic properties and in the thermohaline circulation of the ocean model. Most of these changes originate in the Southern Ocean, emphasizing the crucial role of sea ice in this marginally stably stratified region of the world's oceans. Specifically, if the effect of brine release is neglected, the deep layers of the Southern Ocean warm up considerably; this is associated with a weakening of the Southern Hemisphere overturning cell. The removal of the commonly used “salinity enhancement” leads to a similar effect. The deep-ocean salinity is almost unaffected in both experiments. Introducing explicit new-ice thickness growth in partially ice-covered gridcells leads to a substantial increase in convective activity, especially in the Southern Ocean, with a concomitant significant cooling and salinification of the deep ocean. Possible mechanisms for the resulting interactions between sea-ice processes and deep-ocean characteristics are suggested.

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