Ecosystem Energy Changes

 Jelenka Savković Stevanović

   Faculty of Technology and Metallurgy Belgrade University, Karnegijeva 4, 11000 Belgrade

DOI: https://doi.org/10.51244/IJRSI.2023.1012022

Received: 24 November 2023; Revised: 05 December 2023; Accepted: 08 December 2023; Published: 08 January 2024

 ABSTRACT

In this paper energy in ecosystem  was studied. Energy balance equations of ecosystem were derived. Most of the energy in the Earth’s system comes from just a few sources: solar energy, gravity, radioactive decay, and the rotation of the earth. Earth is constantly changing as energy flows through the system.  Earth’s weather and climate are mostly driven by energy from the Sun.  The Sun provides the energy that drives the water cycle on Earth. In this paper different forms of energy, specific types, using and energy conservation were studied. Environments are highly complex systems whose evolution is determined by complicated networks of positive and negative feedback loops. In this paper macroscopic and microscopic approaches to energy flow through the ecosystem have been used.

Keywords: Ecosystem, energy, environment, sources, balance.

INTRODUCTION

Solar energy drives many surface processes such as winds, currents, the hydrologic cycle, and the overall climate system.

A number of models for plant environment interactions  and particularly  for the utilization  of energy by plant, have been developed since the 1950s. Several of these attempt  to understand  plant growth and water use as related to specific physiological  and environmental parameters [1], [2]. These models, however, can not  be applied  to situations for which few  data are available  unless  a number simplifying  assumptions are used. On the regional  and geographical levels, other models  of a  predominantly  qualitative character  have been suggested [3],[4].  As a consequence of this dichotomous development, attempts  have been made  to  unify these two  approaches with a view to simplifying  the comprehensive models, so as to make them applicable  to regional use to areas with  limited data, without  introducing misleading over simplifications.

In this paper energy sources and  changes of ecosystem were studied.

Energy on the earth

Geologic, fossil, and ice records provide evidence of significant changes throughout Earth’s history. These changes are always associated with changes in the flow of energy through the Earth’s system. Both living and non-living processes have contributed to this change.

Sunlight, gravitational potential, decay of radioactive isotopes, and rotation of the Earth are the major sources of energy driving physical processes on  Earth. Sunlight is a source external to Earth, while radioactive isotopes and gravitational potential, with the exception of tidal energy, are internal. Radioactive isotopes and gravity work together to produce geothermal energy beneath earth’s surface. Earth’s rotation influences the global flow of air and water. For example, unequal warming of Earth’s surface and atmosphere by the Sun drives convection within the atmosphere, producing winds, and influencing ocean currents.

Water plays a major role in the storage and transfer of energy in the Earth system. The major role water plays is a result of water’s prevalence, high heat capacity, and the fact that phase changes of water occur regularly on Earth [5]-[7].

Movement of matter between reservoirs is driven by Earth’s internal and external sources of energy [8]-[12]. These movements are often accompanied by a change in the physical and chemical properties of the matter. Carbon, for example, occurs in carbonate rocks such as limestone, in the atmosphere as carbon dioxide gas, in water as dissolved carbon dioxide, and in all organisms as complex molecules that control the chemistry of life. Energy drives the flow of carbon between these different reservoirs.

Greenhouse gases affect energy flow through the Earth’s system. Greenhouse gases in the atmosphere, such as carbon dioxide and water vapor, are transparent to much of the incoming sunlight but not to the infrared light from the warmed surface of Earth. These gases play a major role in determining average global surface temperatures. When Earth emits the same amount of energy as it absorbs, its average temperature remains stable [13]-[16].

The effects of changes in Earth’s energy system are often not immediately apparent. Responses to changes in Earth’s energy system, input versus output, are often only noticeable over months, years, or even decades.

The Sun is the major source of energy for organisms and the ecosystems of which they are a part. Producers such as plants, algae, and cyanobacteria use the energy from sunlight to make organic matter from carbon dioxide and water. This establishes the beginning of energy flow through almost all food webs.

Food is a biofuel used by organisms to acquire energy for internal living processes. Food is composed of molecules that serve as fuel and building material for all organisms as energy stored in the molecules is released and used. The breakdown of food molecules enables cells to store energy in new molecules that are used to carry out the many functions of the cell and thus the organism.

Energy available to do useful work decreases as it is transferred from organism to organism. The chemical elements that make up the molecules of living things are passed through food chains and are combined and recombined in different ways. At each level in a food chain, some energy is stored in newly made chemical structures, but most are dissipated into the environment. Continual input of energy, mostly from sunlight, keeps the process going.

Energy flows through food webs in one direction, from producers to consumers and decomposers. An organism that eats lower on a food chain is more energy-efficient than one eating higher on a food chain. Eating producers is the lowest and thus most energy-efficient level at which an animal can eat.

Humans are modifying the energy balance of Earth’s ecosystems at an increasing rate. The changes happen, for example, as a result of changes in agricultural and food processing technology, consumer habits, and human population size [7].

DIFFERENT FORMS OF ENERGY

Energy is a paradox: it brings us light, warmth, security, and mobility. But on the other hand, energy extraction, the burning of fossil fuels, and the unequal distribution of energy resources have wrought environmental and social problems for humanity. Energy use is at the root of climate change and many other issues. Today we are seeing the beginnings of a global shift in energy sources and energy policy toward more cooperative, sustainable use of energy. The topics around energy are relevant in all science disciplines as well as in engineering, policy, social science, and economics.

This series of web pages begin with the physics of energy and proceeds through a discussion of energy in biological systems and throughout the Earth’s system. Taken together, these concepts describe energy literacy.

In our daily lives, we constantly interact with different forms of energy. Energy is contained in gasoline, cat food, and stars, and energy moves from one form to another via wind, motion, and heat. So where to begin teaching something that is both intuitively obvious yet abstract and complex? This principle helps students become familiar with some of the fundamentals of energy, much of which is based on physics. We want students to become comfortable with the concept that energy comes in many forms, can be transferred from one system to another, and can be measured. While it is difficult to define the term energy, it is not difficult to identify, describe and measure specific types of energy.

SPECIFIC TYPE OF ENERGY

Mechanical energy is the energy of mechanical systems, such as a ball rolling on a ramp, or a marble fired from a slingshot. Mechanical energy can be in three forms:

• Gravitational potential energy is the energy of an object or system due to gravitational attraction. For example, it can calculate the mechanical energy of a ball that is going to be released from a high window or the gravitational potential energy of the water in a reservoir used for hydropower.
• Kinetic energy is energy due to the motion of an object. A speeding car, a baseball lofting through the air, and a skier sliding downhill are all examples of objects with kinetic energy. Flywheels are a method of storing kinetic energy.
• Elastic potential energy is the energy stored in a stretched spring, rubber band, or other elastic material.

Thermal energy is the energy that results from the kinetic energy of molecules of a substance. A hot tea kettle has more thermal energy than a cold one. Objects that feel warm are emitting thermal energy, and the transfer of thermal energy causes temperature changes.

Radiant energy is the energy from electromagnetic radiation, such as visible light, microwaves, or X-rays.

Chemical energy is energy stored in chemical bonds. Gasoline and food are examples of compounds with chemical potential energy.

Nuclear energy is a name given to the energy that results from mass-to-energy conversion during nuclear reactions. This is a potent and plentiful source of energy because a small amount of mass can be converted into a large amount of energy as described by Einstein’s famous equation . E=mc²

Regardless of what form energy takes, energy has a numerical value that we can measure and assign to objects or systems. When the system undergoes some change, energy can be transformed from one type of energy to another.

ENERGY USE

Every society needs energy. But energy use is tied to many environmental and societal concerns, such as greenhouse gas emissions, mining, pipelines, fracking, and the “embedded energy” in energy infrastructure. No form of energy is free of impacts, but some forms are certainly better than others. Using less energy and using energy efficiently are straightforward ways to reduce the burden on the environment.

The amount of energy use is affected by several factors.

• Energy use can be reduced by limiting wasteful practices by eliminating unnecessary uses of energy, or by opting to use the most efficient form of energy available.
• Technological or social innovation can reduce energy consumption.
• Design of products, technology, or infrastructure can result in lower energy consumption.
• Knowledge of the amount of energy used for different processes can inform decisions about energy use.

These concepts help us understand our consumption of energy, both on an individual level and on a societal scale. Building students’ knowledge of energy consumption can prompt behavioral choices and motivate students to take personal action to reduce energy use. Activities that teach this principle are often designed to have a strong take home message that connects classroom learning to one’s daily life and decisions.

Misconceptions about energy use are commonplace

A persistent misconception implies that reducing energy use equates to a lower standard of living. In fact, the opposite is true in many cases. A modern, efficient car can drive farther on the same amount of fuel compared to an older car. Living nearer to school, work, and community provides many conveniences while reducing the energy needed for transportation. Eating a vegetarian-based diet has many benefits for human health. Educators will have to address the misconception that energy consumption (or even energy waste) is equated with socioeconomic success. That said, in low to middle income nations, access to energy is directly linked to the standard of living. As with many misconceptions, there is an element of truth to this idea.

There are also many folkloric misconceptions about energy use that can be addressed when teaching about energy consumption.

Quantitative skills can strengthen understanding of energy use

Students may place a disproportionate amount of emphasis on relatively small fractions of energy use. For example, while it is a good practice to unplug cell phone chargers when not in use, it saves 16 times more energy to shorten your hot shower by one minute. Similarly, students may get the impression that switching to energy-efficient light bulbs can “solve” the energy problem. By keeping scale in mind, students can appreciate the level of effort that is needed to significantly slow the growth in energy demand.

ENERGY CONSERVATION

Conservation of energy has two very different meanings. There is the physical law of conservation of energy. This law says that the total amount of energy in the universe is constant. Conserving energy is also commonly used to mean the decreased use of societal energy resources. When speaking of people conserving energy, this second meaning is always intended.

One way to manage energy resources is through conservation. Conservation includes reducing wasteful energy use, using energy for a given purpose more efficiently, making strategic choices as to sources of energy, and reducing energy use altogether.

Human demand for energy is increasing. Population growth, industrialization, and socioeconomic development result in increased demand for energy. Societies have choices with regard to how they respond to this increase. Each of these choices has consequences.

Earth has limited energy resources. Increasing human energy consumption places stress on the natural processes that renew some energy resources and it depletes those that cannot be renewed.

Social and technological innovation affects the amount of energy used by human society. The amount of energy society uses per capita or in total can be decreased. Decreases can happen as a result of technological or social innovation and change. Decreased use of energy does not necessarily equate to decreased quality of life. In many cases, it will be associated with increased quality of life in the form of increased economic and national security, reduced environmental risks, and monetary savings.

Behavior and design affect the amount of energy used by human society. There are actions individuals and society can take to conserve energy. These actions might come in the form of changes in behavior or in changes to the design of technology and infrastructure. Some of these actions have more impact than others.

Products and services carry with them embedded energy. The energy needed for the entire life cycle of a product or service is called the “embedded” or “embodied” energy. An accounting of the embedded energy in a product or service, along with knowledge of the source(s) of the energy, is essential when calculating the amount of energy used and in assessing impacts and consequences.

Amount of energy used can be calculated and monitored. An individual, organization, or government can monitor, measure, and control energy use in many ways. Understanding utility costs, knowing where consumer goods and food come from, and understanding energy efficiency as it relates to home, work, and transportation are essential to this process.

ENERGY BALANCE EQUATIONS OF ECOSYSTEM 

The disposition of radiant energy at the surface of the earth is of prime importance  for understanding  soil-water balances and  the related chemical transport and transformation processes. A formalized transcription  of the energetic relationships yields the following form of the energy balance equation:

R_n+H_s+H_a+r_ET=0                             (1)

In this equation, which summarizes the solar energy cascade with its numerous  regulation and transformation  components, any form of energy  that is flowing toward the surface is considered positive and any form  that is moving away from it is considered negative.  is the net radiation flux,  is the heat flow  in soil at the surface, is the sensible heat transfer through air at the surface, and is the transfer rate  of latent heat due to evapotranspiration.

R_n is net energy and can be defined:

Solar radiation is defined as:

 the long-wave counter, radiation counter  of the lower atmosphere is:

if diffusion neglected.

  the sensible heat transfer through air at the surface

  the heat flow  in soil at the surface:

If neglected changes in y and z direction is obtained:

 the transfer rate  of latent heat due to evapotranspiration is:

Conventionally, all terms  are expressed in joules per minute and square  centimeters, 4.19cm^-2   min ^-1 equals ca.  of  water depth evaporated per hour.

The Earth’s surface receives short- wave and long- wave  counter radiation  from the atmosphere, while  itself emitting long-wave radiation. Whereas photochemical reactions are controlled mostly  by short- wave radiation, the diurnal  variability  of surface temperature  and the related energy  fluxes are very much  under the influence of long-wave radiation. Thus, the net radiation flux    may be derived from the short  and long-wave radiation balances as shown in (2), where the solar radiation  involves direct beam radiation  and diffuse radiation , each term comprising short-wave and solar long-wave components  is the long-wave  radiation counter  of the lower atmosphere, the long-wave radiation from the Earth’s surface (Stefan-Bolzmann radiation),  the reflectivity.

The rate at which heat is transferred down wards into the soil and subsurface substrate  is directly related  to the nature and efficiency  of the distribution mechanisms. In solids, heat is redistributed by conduction, and the flow rate  depends on thermal conductivity,  Units are watts  per meter per degree, or joules per centimeter per second per degree Celsius, . Under steady state conditions, the flow of heat  is related to the temperature gradient  and the thermal conductivity  by

A major problem in soils is that steady state conditions are rarely  achieved  and thermal conductivity is a complicated function of granulometry, mineralogical  composition, compaction, and water content.  The conventional determination of thermal conductivity is consequently fairly  difficult.  An alternative parameter, thermal diffusivity, is used, which is given by , where  denotes the specific heat and  the density, units are square meters per second. For homogenous medium, thermal diffusivity defines the rate at which temperature changes   take place as in (8).

Where  temperature,  chemical reaction heat,  interphase heat transfer,  space coordinate,  geometrical velocity,  some heat generation,  attribute of interest and  is time.

The magnitude of the heat flow into the air at the surface  can be obtained by a difference when the other components of the energy balance in equation (1) are measured, or it can be determined directly. Among the latter approaches, two methods, the aerodynamic method  Sverdrup–Albrecht method merit particular attention.

The aerodynamic methods is based on very precise determinations of the vertical temperature and wind profiles, and involves a horizontal homogeneity  of the surface over considerable distances  in the luff of the measuring station.

The Sverdrup-Albrecht method determines  either  and  as components of the energy balance in equation (11):

The ratio  (Bowen ratio) can be estimated from measurements of the vertical gradients of temperature  and vapor pressure  above the surface.

The latent heat flux can be estimated as a result of vaporization  or condensation of  water. Consequently, five general methods are used  to evaluate  the water  vapor flux  caused by evaportranspiration.

Thornthwaite and Holzman [3] suggested

where  average  water vapor, ,,  the air density, ,  the average wind speed,  the average  elevation  above surface, and  von Karman’s constant, 0.4.

A continuous record of water  vapor convention  by means  of eddy-correlation techniques  as described by Dyer [16] yields estimates of  by

where  the momentary vertical wind  speed, and  the instantaneous  value  of water vapor concentration. The problem  of measuring   as the time average  of the vertical flux  of water vapor thus becomes  one of designing  instrumentation  capable  of measuring  the turbulent  air motion and structure of .  This involves equipment whose response  time is  sufficiently short to take account  of all frequencies in the turbulent  spectrum  contributing  significantly to the flux. This requirement  depends  on both  the height of measurement  and the ability  of the air, which  means,  in general terms, that the  sensing  elements should respond  adequately  to signals with  a period of .

If all terms of energy budget are known  except the flux due  to evaporation ( or evaportan spiration), the latter can be obtained by a difference.  Finally the latent heat flux can be found  by direct measurement, i.e., by means of weighing lysimeters  on the local scale  or as the  difference term  of the water budget of a drainage system on the regional scale.

Notation

-denotes the specific heat,

 – the sensible  heat transfer through air at the

    surface ,

– the heat flow  in soil at the surface,

 -the transfer rate  of latent heat due to

        evapotranspiration,

 – the net radiation flux,

 – average  water vapor

– generation heat,

-temperature,

– the average wind speed,

 – geometrical velocity,

– momentary vertical wind  speed,,

  – average  elevation  above surface,

 space coordinate

Greek symbols

– reflectivity

-latent heat of chemical reaction,

– interphase heat exchange,

 – thermal conductivity,

– attribute of interest

– density,

CONCLUSION

In this paper energy balance equations  in ecosystem were derived. Ecosystems are affected by changes in the availability of energy and matter. The amount and kind of energy and matter available constrain the distribution and abundance of organisms in an ecosystem and the ability of the ecosystem to recycle materials.

Macroscopic and microscopic  levels of description to energy flow through the ecosystem were applied. Entropy analysis was not taken account.

Humans are part of Earth’s ecosystems and influence energy flow through these systems. Energy’s influence on human society is explored from the point of view of different sources of energy, how it use energy, how it make decisions about energy, and the society-wide impacts of energy use.

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