Modelling key variables for understanding the effects of grazing and nutrient recycling by zooplankton on the freshwater microbial loop

2021 ◽  
Author(s):  
Luca Schenone ◽  
Beatriz Modenutti ◽  
Nicolás Martyniuk ◽  
Marcela Bastidas Navarro ◽  
Cecilia Laspoumaderes ◽  
...  
Keyword(s):  
Nutrient Recycling ◽  
Microbial Loop ◽  
Key Variables

scholarly journals Examination of the role of the microbial loop in regulating lake nutrient stoichiometry and phytoplankton dynamics

2014 ◽  
Vol 11 (11) ◽  
pp. 2939-2960 ◽  
Author(s):  
Y. Li ◽  
G. Gal ◽  
V. Makler-Pick ◽  
A. M. Waite ◽  
L. C. Bruce ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Nutrient Recycling ◽  
Ecosystem Model ◽  
Microbial Loop ◽  
Phytoplankton Growth ◽  
Microbial Interactions ◽  
Trophic Levels ◽  
Nitrogen And Phosphorus ◽  
Available N

Abstract. The recycling of organic material through bacteria and microzooplankton to higher trophic levels, known as the "microbial loop", is an important process in aquatic ecosystems. Here the significance of the microbial loop in influencing nutrient supply to phytoplankton has been investigated in Lake Kinneret (Israel) using a coupled hydrodynamic–ecosystem model. The model was designed to simulate the dynamic cycling of carbon, nitrogen and phosphorus through bacteria, phytoplankton and zooplankton functional groups, with each pool having unique C : N : P dynamics. Three microbial loop sub-model configurations were used to isolate mechanisms by which the microbial loop could influence phytoplankton biomass, considering (i) the role of bacterial mineralisation, (ii) the effect of micrograzer excretion, and (iii) bacterial ability to compete for dissolved inorganic nutrients. The nutrient flux pathways between the abiotic pools and biotic groups and the patterns of biomass and nutrient limitation of the different phytoplankton groups were quantified for the different model configurations. Considerable variation in phytoplankton biomass and dissolved organic matter demonstrated the sensitivity of predictions to assumptions about microbial loop operation and the specific mechanisms by which phytoplankton growth was affected. Comparison of the simulations identified that the microbial loop most significantly altered phytoplankton growth by periodically amplifying internal phosphorus limitation due to bacterial competition for phosphate to satisfy their own stoichiometric requirements. Importantly, each configuration led to a unique prediction of the overall community composition, and we conclude that the microbial loop plays an important role in nutrient recycling by regulating not only the quantity, but also the stoichiometry of available N and P that is available to primary producers. The results demonstrate how commonly employed simplifying assumptions about model structure can lead to large uncertainty in phytoplankton community predictions and highlight the need for aquatic ecosystem models to carefully resolve the variable stoichiometry dynamics of microbial interactions.

scholarly journals A numerical analysis of the role of the microbial loop in regulating nutrient stoichiometry and phytoplankton dynamics in a eutrophic lake

2013 ◽  
Vol 10 (12) ◽  
pp. 19731-19772
Author(s):  
Y. Li ◽  
G. Gal ◽  
V. Makler-Pick ◽  
A. M. Waite ◽  
L. C. Bruce ◽  
...  
Keyword(s):  
Phytoplankton Biomass ◽  
Nutrient Recycling ◽  
Eutrophic Lake ◽  
Microbial Loop ◽  
Phytoplankton Growth ◽  
Microbial Interactions ◽  
Trophic Levels ◽  
Nitrogen And Phosphorus ◽  
Available N

Abstract. The recycling of organic material through bacteria and microzooplankton to higher trophic levels, known as the "microbial loop", is an important process in aquatic ecosystems. Here the significance of the microbial loop in influencing nutrient supply to phytoplankton is investigated in Lake Kinneret (Israel) using a coupled hydrodynamic-ecosystem model. The model was designed to simulate the dynamic cycling of carbon, nitrogen and phosphorus through bacteria, phytoplankton and zooplankton functional groups, with each pool having unique C : N : P dynamics. Three microbial loop sub-model configurations were used to isolate mechanisms by which the microbial loop could influence phytoplankton biomass, considering: (i) the role of bacterial mineralization, (ii) bacterial ability to compete for dissolved inorganic nutrients, and (iii) the effect of micrograzer excretion. The nutrient flux pathways between the abiotic pools and biotic groups and the patterns of biomass and nutrient limitation of the different phytoplankton groups were quantified for the different model configurations. Considerable variation in phytoplankton biomass and dissolved organic matter demonstrated the sensitivity of predictions to assumptions about microbial loop operation and the specific mechanisms by which phytoplankton growth was affected. Comparison of the simulations identified that the microbial loop most significantly altered phytoplankton growth by periodically amplifying internal phosphorus limitation due to bacterial competition for phosphate to satisfy their own stoichiometric requirements. Importantly, each configuration led to a unique prediction of the overall community composition, and we conclude that the microbial loop plays an important role in nutrient recycling by regulating not only the quantity, but also the stoichiometry of available N and P that is available to primary producers. The results demonstrate how commonly employed simplifying assumptions about model structure can lead to large uncertainty in phytoplankton community predictions and highlight the need for aquatic ecosystem models to carefully resolve the variable stoichiometry dynamics of microbial interactions.

Fe(III)-carboxylate photochemistry in polysaccharide hydrogels for a green chemistry approach to nutrient recycling and surface modification of materials

2020 ◽  
Author(s):  
Mudugamuwe Jayan Savinda Karunarathna ◽  
Alexis D. Ostrowski ◽  
W. Robert Midden
Keyword(s):  
Surface Modification ◽  
Green Chemistry ◽  
Nutrient Recycling ◽  
Modification Of Materials

Referral Patterns for Youths Identified at Risk for Suicide by Trained Gatekeepers

Crisis ◽  
2012 ◽  
Vol 33 (2) ◽  
pp. 113-119 ◽  
Author(s):  
Michael S. Rodi ◽  
Lucas Godoy Garraza ◽  
Christine Walrath ◽  
Robert L. Stephens ◽  
D. Susanne Condron ◽  
...  
Keyword(s):  
Suicide Prevention ◽  
Demographic Characteristics ◽  
Service Access ◽  
Referral Patterns ◽  
Race And Gender ◽  
Lee Smith ◽  
Prevention Behavior ◽  
Key Variables ◽  
And Gender ◽  
To Receive

Background: In order to better understand the posttraining suicide prevention behavior of gatekeeper trainees, the present article examines the referral and service receipt patterns among gatekeeper-identified youths. Methods: Data for this study were drawn from 26 Garrett Lee Smith grantees funded between October 2005 and October 2009 who submitted data about the number, characteristics, and service access of identified youths. Results: The demographic characteristics of identified youths are not related to referral type or receipt. Furthermore, referral setting does not seem to be predictive of the type of referral. Demographic as well as other (nonrisk) characteristics of the youths are not key variables in determining identification or service receipt. Limitations: These data are not necessarily representative of all youths identified by gatekeepers represented in the dataset. The prevalence of risk among all members of the communities from which these data are drawn is unknown. Furthermore, these data likely disproportionately represent gatekeepers associated with systems that effectively track gatekeepers and youths. Conclusions: Gatekeepers appear to be identifying youth across settings, and those youths are being referred for services without regard for race and gender or the settings in which they are identified. Furthermore, youths that may be at highest risk may be more likely to receive those services.

Faculty selection of textbooks: Key variables and the role of teaching experience

2010 ◽  
Author(s):  
Aja Taitano ◽  
Bradley Smith ◽  
Cade Hulbert ◽  
Kristin Batten ◽  
Lalania Woodstrom ◽  
...  
Keyword(s):  
Teaching Experience ◽  
Key Variables ◽  
Faculty Selection ◽  
Selection Of

Computer simulation to evaluate the economics of landfill gas recovery

1998 ◽  
Vol 38 (2) ◽  
pp. 201-208
Author(s):  
M. W. Milke
Keyword(s):  
Computer Simulation ◽  
Computer Program ◽  
Landfill Gas ◽  
Base Case ◽  
Simulation Tool ◽  
Hypothetical Case ◽  
Gas Recovery ◽  
Fixed Set ◽  
Key Variables ◽  
Simulation Results

A need exists for tools to improve evaluations of the economics of landfill gas recovery. A computer simulation tool is presented. It uses a spreadsheet computer program to calculate the economics for a fixed set of inputs, and a simulation program to consider variations in the inputs. The method calculates the methane generated each year, and estimates the costs and incomes associated with the recovery and sale of the gas. Base case results are presented for a city of 500,000. An uncertainty analysis for a hypothetical case is presented. The simulation results can help an analyst see the key variables affecting the economics of a project.

Enhancement in productivity and income sustainability through Integrated farming system approaches for small and marginal farmers of Eastern India

2017 ◽  
Vol 4 (2) ◽  
Author(s):  
SANJEEV KUMAR ◽  
SHIVANI . ◽  
S. K. SAMAL ◽  
S. K. DWIVEDI ◽  
MANIBHUSHAN .
Keyword(s):  
Nutrient Recycling ◽  
Farming Systems ◽  
Fruit Trees ◽  
Farming System ◽  
Eastern Region ◽  
Net Income ◽  
System Productivity ◽  
Integrated Farming ◽  
Systems Models ◽  
The Cost

Integration of different components viz. livestock, fishery, horticulture, mushroom etc. along with field crops not only enhanced productivity but by-products (waste) of one component act as input for another component through resource recycling within the system. Six integrated farming systems models with suitable combinations of Crop, vegetables, fruit trees, fish, livestock, mushroom etc. were made and evaluated at the experimental farm of ICAR Research Complex for Eastern Region, Patna during 2012-16 for harness maximum income, nutrient recycling and employment. Among six combinations, crop + fish + duck + goat resulted as most profitable combination in terms of productivity (RGEY- 22.2t), net income (Rs. 2,15,900/ha), additional employment (170 days/year) with income sustainability index (ISI) by 90.2. Upon nutrient recycling prepared from different wastes from the system Crop + fish + duck + goat combination added N (56.5 kg), P (39.6 kg) and K (42.7 kg) into the soil and reduced the cost of cultivation by 24 percent and was followed by crop + fish + goat combination. Crops grown under IFS mode with different types of manures produced 31 percent higher yield over conventional rice- wheat system. The contribution of crops towards the system productivity ranged from 36.4 to 56.2 %, while fish ranged from 22.0-33.5 %; for goat 25.4-32.9 %; for poultry 38.7 %; for duck 22.0-29.0 %; for cattle 32.2% and for mushroom 10.3 %.

Ethical leadership and its role in organizational integrity to reduce the nutrients of administrative corruption

2017 ◽  
Vol 3 (2) ◽  
pp. 272
Author(s):  
Yousef Hajim Al-Taie ◽  
Darwn Faraidun Abdulla ◽  
Wrya Najm Rasheed
Keyword(s):  
Decision Making ◽  
Ethical Leadership ◽  
Multiple Control ◽  
Negative Behaviors ◽  
Appropriate Behavior ◽  
Positive Side ◽  
Organizational Integrity ◽  
Key Variables ◽  
Independent Variable ◽  
Lack Of Commitment

The ethical  leadership is considered as one of the most  vital  practices , leadership styles and as an aspects of appropriate behavior to build organizational social relationships between the human capital in organization and its outside , and characterized their relationship by two-way , between the superior and subordinate from one way and  between them and the society on the other hand, in order to focus on strengthen relations processes and the appropriate decision making  in accordance with the behaviors of ethical  leadership Which focuses in its philosophy on credibility, trust and justice in the distribution of decision-making among individuals, and the most important thing that  individuals need is to encourage ethical values that limit the behavior of perverse action or negative behavior, and whenever  the leadership does ethically, they may  led to achieve organizational integrity, which emphasizes its philosophy to avoid negative behaviors or illegal and adhere by the behavior rules and ethical discipline  that would limit from the behavior of deviant corruption or rooted in the organizations. Organizational integrity it deliberated as the most significant aspects of the development of organizations in the third millennium, which focuses socially on the forces of work and highlight the positive side of the Organization activities and educating and training of individuals on such those kind of actions, taking into consideration its impact on the external environment and adherence to ethical standards and principles that they have a mental acceptance. Therefore, it can be said that through ethical leadership and organizational integrity, organizations can reduce the spread of administrative corruption and eliminate its nutrients and incubators by fostering a culture of ethical leadership and working with the principles of organizational integrity within the wholly organization. Hence, the current study focused on the three key variables.  The independent variable is the ethical leadership, according to the model of (Sajefert et al..2016), with its dimension which includes (Justice, ethical principles, orientation towards individuals, separation between authorities, classification and anxiety bearing), while the mediator variable is the organizational integrity which were applied based on the model of (Moon & Hamition: 2013), which its sub-dimensions consists of  (critical task, supervision, focus on the process, focus on efficiency, human resource, trust, learning and improvement, change management). However,  the dependent variable of our study is nutrients of administrative corruption including  the dimensions, which have been obtained from the preliminary study of a number of experts and academics, as identified as more than twenty dimensions and  then the following dimensions, which have been got the agreement between most of the experts, are  (mortal routine, job Infiltration during work, career lazing, partisan interest, multiple control points, lack Importance in specialization, carelessness, lack of commitment, lack of knowledge of the profession ethics, Competencies and incompetence Conflict, the lack of strict laws and regulations, linking salary to productivity). Questionnaires were designed and which have been pre-tested for data collection and measurements were developed using a random sampling method. The questionnaires were distributed for the sample of 70 employees in three important departments in Najaf Governorate (Tax Department, State Real Estate Department and Registration Department) to be a part of the current study. Numerical statistical methods were applied, including mean, standard deviation, percent weight, C.V, and simple and multiple linear regressions using SMART PLS program. The results showed a positive correlation among the three variables in varying proportions. Based on the results of the current study, a number of recommendations were suggested to strengthen the importance of ethical leadership in achieving organizational integrity as well as to reduce the spread of administrative corruption and eliminate its nutrients and incubators in other organizations.

scholarly journals Landscape Design toward Urban Resilience: Bridging Science and Physical Design Coupling Sociohydrological Modeling and Design Process

2021 ◽  
Vol 13 (9) ◽  
pp. 4666
Author(s):  
Yoonshin Kwak ◽  
Brian Deal ◽  
Grant Mosey
Keyword(s):  
Pilot Study ◽  
Landscape Design ◽  
Urban Systems ◽  
Urban Resilience ◽  
Planning Support Systems ◽  
Creative Solutions ◽  
Resilient Communities ◽  
Study Support ◽  
Key Variables ◽  
Resilient Design

Given that evolving urban systems require ever more sophisticated and creative solutions to deal with uncertainty, designing for resilience in contemporary landscape architecture represents a cross-disciplinary endeavor. While there is a breadth of research on landscape resilience within the academy, the findings of this research are seldom making their way into physical practice. There are existent gaps between the objective, scientific method of scientists and the more intuitive qualitative language of designers and practitioners. The purpose of this paper is to help bridge these gaps and ultimately support an endemic process for more resilient landscape design creation. This paper proposes a framework that integrates analytic research (i.e., modeling and examination) and design creation (i.e., place-making) using processes that incorporate feedback to help adaptively achieve resilient design solutions. Concepts of Geodesign and Planning Support Systems (PSSs) are adapted as part of the framework to emphasize the importance of modeling, assessment, and quantification as part of processes for generating information useful to designers. This paper tests the suggested framework by conducting a pilot study using a coupled sociohydrological model. The relationships between runoff and associated design factors are examined. Questions on how analytic outcomes can be translated into information for landscape design are addressed along with some ideas on how key variables in the model can be translated into useful design information. The framework and pilot study support the notion that the creation of resilient communities would be greatly enhanced by having a navigable bridge between science and practice.

Agronomic potential of biosolids for a sustainable sanitation management in Brazil: Nutrient recycling, pathogens and micropollutants

2021 ◽  
Vol 289 ◽  
pp. 125708
Author(s):  
Sérgio Siqueira Amorim Junior ◽  
Valéria Sun Hwa Mazucato ◽  
Beatriz dos Santos Machado ◽  
Denilson de Oliveira Guilherme ◽  
Reginaldo Brito da Costa ◽  
...  
Keyword(s):  
Nutrient Recycling ◽  
Agronomic Potential
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