MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
TOPICS
I.
II.
III.
IV.
V.
Introduction to Environmental Science and Engineering
Ecology and Ecosystem
Biogeochemical Cycles
Environmental Laws and Regulations
Sustainability and Cradle-to-Cradle Design
INTENDED LEARNING OUTCOME
At the end of this module, you should be able to
1. Discuss basic principles and definitions of terms associated in the study of
environmental science and engineering.
2. Define ecology and the ecosystems comprising the environment.
3. Examine in detail some of the major biogeochemical cycles.
4. State and discuss the importance of environmental laws and regulations in the
Philippines setting.
5. Apply the concepts of sustainability and strategies for achieving sustainable materials
and energy management.
I. INTRODUCTION TO ENVIRONMENTAL SCIENCE AND ENGINEERING
A. What is environmental science?
It is the science of physical phenomena in the environment. It studies of the sources, reactions,
transport, effect and fate of physical and biological species in the air, water and soil and the
effect of human activity upon these.
▪ It is a multi-disciplinary science because it comprises various branches of studies like
chemistry, physics, medical science, life science, agriculture, public health, engineering
etc.
Definitions of Environment
▪ The term environment is used to describe, in the aggregate, all the external forces,
influences and conditions, which affect the life, nature, behavior and the growth,
development and maturity of living organisms (Douglas and Holland)
▪ It embraces all those disciplines which are concerned with the physical, chemical,
and biological surroundings in which organisms live.
Scope of Environment
▪ The scope of the term Environment has been changing and widening by the passage of
time. In the primitive age, the environment consisted of only physical aspects of the
planted earth's land, air and water as biological communities. As the time passed on man
extended his environment through his social, economic and political functions.
1.
Atmosphere: The atmosphere implies the protective blanket of gases, surrounding the
earth:
a. It sustains life on the earth.
b. It saves it from the hostile environment of outer space.
c. It absorbs most of the cosmic rays from outer space and a major portion of the
electromagnetic radiation from the sun.
d. It transmits only here ultraviolet, visible, near infrared radiation (300 to 2500 nm)
and radio waves. (0.14 to 40 m) while filtering out tissue-damaging ultraviolet waves
below about 300 nm.
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
The atmosphere is composed of nitrogen and oxygen. Besides, argon, carbon dioxide,
and trace gases.
2. Hydrosphere: The Hydrosphere comprises all types of water resources oceans, seas,
lakes, rivers, streams, reservoir, polar icecaps, glaciers, and ground water.
a. Nature 97% of the earth’s water supply is in the oceans,
b. About 2% of the water resources is locked in the polar icecaps and glaciers.
c. Only about 1% is available as fresh surface water-rivers, lakes streams, and ground
water fit to be used for human consumption and other uses.
3. Lithosphere: Lithosphere is the outer mantle of the solid earth. It consists of minerals
occurring in the earth’s crusts and the soil e.g., minerals, organic matter, air and water.
4. Biosphere: Biosphere indicates the realm of living organisms and their interactions
with environment, viz atmosphere, hydrosphere and lithosphere.
Importance of Environment Studies
▪ The environment studies enlighten us about the importance of protection and
conservation of our indiscriminate release of pollution into the environment.
Structure of Environment
Environment is both physical and biological. It includes both living and non-living components.
1.
Physical Environment
The Physical Environment is classified into three broad categories viz.
a. Solid,
b. Liquid
c. Gas.
These represent the following spheres:
a. The lithosphere (solid earth)
b. The hydrosphere (water component) and
c. The atmosphere
As such, the three basics of physical environment may be termed as under:
a. Lithospheric Environment
b. Hydrospheric Environment
c. Atmospheric Environment
The scientists have classified them into smaller units based on different spatial scales,
e.g.
a. Mountain Environment
b. Glacier Environment
c. Plateau Environment
d. Coastal Environment
2.
Biological Environment
The biological of the environment consists of:
a. Plants (flora)
b. Animals (fauna)
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
B. What is environmental engineering?
Engineering is a profession that applies science and mathematics to make the properties of
matter and sources of energy useful in structures, machines, products, systems and processes.
Environmental Engineering
ASCE Definition (show relationship between environmental science and environmental
engineering)
▪ Environmental engineering is manifest by sound engineering thought and practice in
the solution of problems of environmental sanitation, notably in the provision of safe,
palatable, and ample public supplies; the proper disposal of or recycle of wastewater and
solid wastes; the adequate drainage of urban and rural areas for proper sanitation; and
the control of water, soil, and atmospheric pollution, and the social and environmental
impact of these solutions.
Furthermore, it is concerned with problems in the field of public health such as control of
arthropod-borne diseases, the elimination of industrial health hazards and the provision of
adequate sanitation in urban, rural, and recreation areas, and the effect of technological
advances on the environment.
C. How environment engineers and scientist work?
Old’s sayings: “Scientists discover things and engineers make them work.”
From an educational point of view – environmental engineering is found on environmental
science. Environmental science and, in particular, quantitative environmental science provide
the fundamental theories used by environmental engineers to design solutions for
environmental problems. In many instances the tasks and tools of environmental scientists and
environmental engineers are the same.
Examples:
1. Impact of dam on the oxygen in the river and its ability to support fish life.
Solution: Design a fish ladder that not provided a means for a fish to bypass the dam but also
aerated the water to the DO.
Activity:
ES: Provide the knowledge of the depth of water and height of the steps the fish could
negotiate
EE: Determine the structural requirements of the bypass to allow enough water to flow
around the dam to provide the required depth.
Three-fold purpose of environmental engineering:
1. the protection of human activity from adverse environmental factors
2. the protection of ecosystems (local or global) from the potentially harmful effects of
human activities
3. the improvement of environmental quality
D. Systems Approach
A system is a set of components that function and interact in some regular way. The human
body, a river, an economy, and the earth are all systems.
• looking at all the interrelated parts and their effects on one another
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
•
to simplify the system to trustable size that behaves in a fashion similar to the real
system. The simplified model does not behave in detail as the system does, but it gives
a fair approximation of what is going on.
Most systems have the following key components: inputs from the environment, flows or
throughputs of matter and energy within the system at certain rates, and outputs to the
environment (see Figure 1)
▪
▪
Such systems depend on inputs of matter and energy resources and outputs of waste
and heat to the environment.
Such a system can become unsustainable if the throughput of matter and energy
resources exceeds the ability of the earth’s natural capital to provide the required
resource inputs or the ability of the environment to assimilate or dilute the resulting
heat, pollution, and environmental degradation.
Figure 1: Inputs, throughput, and outputs of an economic system
(Adopted from Miller, G. Tyler, Jr. and Scott E. Spoolman (2009). Essentials of Ecology, 5th)
Systems Respond to Change through Feedback Loops
Most systems are affected one way or another by feedback, any process that increases (positive
feedback) or decreases (negative feedback) a change to a system. Such a process, called a
feedback loop, occurs when an output of matter, energy, or information is fed back into the
system as an input and leads to changes in that system.
▪
A positive feedback loop causes a system to change further in the same direction
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
Figure 2 Positive feedback loop
When vegetation was removed from a stream valley, flowing water from precipitation caused
erosion and loss of nutrients, which caused more vegetation to die. With even less vegetation
to hold soil in place, flowing water caused even more erosion and nutrient loss, which caused
even more plants to die (Hubbard Brook experiment).
▪
A negative, or corrective, feedback loop causes a system to change in the opposite
direction from which is it moving.
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
Figure 3 Negative feedback loop
When the furnace in a house is turned on and begins heating the house, the thermostat can be
set to turn the furnace off when the temperature in the house reaches the set number. The house
then stops getting warmer and starts to cool.
Question 1
1. Define and give an example of a system? Distinguish among the input, flow
(throughput), and output of a system.
2. How might experimenters have employed a negative feedback loop to stop, or correct,
the positive feedback loop that resulted in increasing erosion and nutrient losses in the
Hubbard Brook experimental forest?
Three environmental systems of importance
1. Water resource management
▪ water quality management
▪ water treatment
▪ wastewater treatment
2. Air resource management
▪ quantity and quality of air
▪ cost-benefit analysis
3. Solid waste management
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
Waste Generation
Storage
Collection
Transfer and
transport
Processing and
recovery
Disposal
Multimedia systems
- environmental problems cross the air-water-soil boundary.
Examples:
1. Acid rain resulting from the emission of SO2 & NO2 in the atmosphere
2. Solid waste incineration results in air pollution which in turn is controlled by scrubbing
with water, resulting in a water pollution problem
II. ECOLOGY AND ECOSYSTEM
A. What is ecology?
- Ecology (from the Greek words oikos, meaning “house” or “place to live,” and logos,
meaning “study of”) is the study of how organisms interact with their living (biotic)
environment of other organisms and with their nonliving (abiotic) environment of soil,
water, other forms of matter, and energy mostly from the sun. In effect, it is a study of
connections in nature.
Ecology is the study of how organisms interact with one another and with their physical
environment of matter and energy.
Ecologists focus on organisms, populations, communities, ecosystems, and the biosphere.
▪ A population is a group of individuals of the same species that live in the same place at the
same time.
Examples: school of glassfish in the Red Sea
field mice living in a cornfield
monarch butterflies clustered in a tree
people in a country
genetic diversity - individuals vary slightly in their genetic makeup
habitat - where a population or an individual organism normally lives
▪
A community, or biological community, consists of all the populations of different
species that live in a particular place.
Examples:
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
a catfish species in a pond usually shares the pond with other fish species, and with
plants, insects, ducks, and many other species that make up the community
Organisms in a community interact with one another in feeding and other relationships.
▪
An ecosystem is a community of different species interacting with one another and with
their nonliving environment of soil, water, other forms of matter, and energy, mostly from
the sun.
- Ecosystems can range in size from a puddle of water to an ocean, or from a patch of
woods to a forest.
- Ecosystems can be natural or artificial (human created).
Examples: crop fields, tree farms, and reservoirs
▪
The biosphere consists of the parts of the earth’s air, water, and soil where life is found. In
effect, it is the global ecosystem in which all organisms exist and can interact with one
another.
Question 2
How do the concepts of community and ecosystem differ?
B. What Keeps Us and Other Organisms Alive?
Earth’s life-support system consists of four main spherical systems that interact with one
another - the atmosphere (air), the hydrosphere (water), the geosphere (rock, soil, sediment),
and the biosphere (living things).
▪
Atmosphere - thin spherical envelope of gases surrounding the earth’s surface
- extends only about 17 kilometers (11 miles) above sea level at the tropics and about 7
kilometers (4 miles) above the earth’s north and south poles
- It contains the majority of the air that we breathe, consisting mostly of nitrogen
(78% of the total volume) and oxygen (21%).
- The remaining 1% of the air includes water vapor, carbon dioxide, and methane, all
of which are called greenhouse gases, because they trap heat and thus warm the
lower atmosphere.
Stratosphere - stretching 17–50 kilometers (11–31 miles) above the earth’s surface
- Its lower portion contains enough ozone (O3) gas to filter out most of the sun’s
harmful ultraviolet radiation. This global sunscreen allows life to exist on land and
in the surface layers of bodies of water.
▪
Hydrosphere - consists of all of the water on or near the earth’s surface.
- It is found as liquid water (on the surface and underground), ice (polar ice, icebergs,
and ice in frozen soil layers called permafrost), and water vapor in the atmosphere.
- Most of this water is in the oceans, which cover about 71% of the globe.
▪
Geosphere - consists of the earth’s intensely hot core, a thick mantle composed mostly of
rock, and a thin outer crust.
- Most of the geosphere is located in the earth’s interior. Its upper portion contains
nonrenewable fossil fuels and minerals that we use, as well as renewable soil
chemicals that organisms need in order to live, grow, and reproduce.
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
The biosphere occupies those parts of the atmosphere, hydrosphere, and geosphere where life
exists.
- it includes the lower part of the atmosphere, most of the hydrosphere, and the
uppermost part of the geosphere
The goal of ecology is to understand the interactions in this thin layer of air, water, soil, and
organisms.
Three Factors Sustain Life on Earth
▪ Life is sustained by the flow of energy from the sun through the biosphere, the cycling of
nutrients within the biosphere, and gravity.
1.
The one-way flow of high-quality energy from the sun, through living things in their
feeding interactions, into the environment as low-quality energy (mostly heat dispersed
into air or water at a low temperature), and eventually back into space as heat.
- The first and second laws of thermodynamics govern these. (High-quality energy
cannot be recycled!)
2. The cycling of matter or nutrients (the atoms, ions, and compounds needed for survival
by living organisms) through parts of the biosphere.
- The law of conservation of matter governs this this nutrient cycling process.
(Nutrient movements in ecosystems and in the biosphere are round-trips, which
can take from seconds to centuries to complete.)
3. Gravity, which allows the planet to hold onto its atmosphere and helps to enable the
movement and cycling of chemicals through the air, water, soil, and organisms.
C. What Are the Major Components of an Ecosystem?
Ecosystems Have Living and Nonliving Components
▪ Abiotic - consists of nonliving components such as water, air, nutrients, rocks, heat, and
solar energy
▪
Biotic - consists of living and once living biological components - plants, animals, and
microbes
- Biotic factors also include dead organisms, dead parts of organisms, and the
waste products of organisms.
Different species and their populations thrive under different physical and chemical conditions.
Some need bright sunlight; others flourish in shade. Some need a hot environment; others prefer
a cool or cold one. Some do best under wet conditions; others thrive under dry conditions.
Producers and Consumers Are the Living Components of Ecosystems
Ecologists assign every organism in an ecosystem to a feeding level, or trophic level, depending
on its source of food or nutrients. The organisms that transfer energy and nutrients from one
trophic level to another in an ecosystem can be broadly classified as producers and consumers.
1. Producers, sometimes called autotrophs (self-feeders), make the nutrients they need from
compounds and energy obtained from their environment.
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
Examples:
a. green plants generally capture about 1% of the solar energy that falls on their
leaves and convert it to chemical energy stored in organic molecules such as
carbohydrates
b. algae and aquatic plants are the major producers near shorelines
c. phytoplankton - mostly microscopic organisms that float or drift in the water
Most producers capture sunlight to produce energy rich carbohydrates (such as glucose,
C6H12O6) by photosynthesis, which is the way energy enters most ecosystems.
carbon dioxide + water + solar energy → glucose + oxygen
6 CO2 + 6 H2O + solar energy → C6H12O6 + 6 O2
For instance, chlorophyll acts as an antenna, absorbing the light energy, which is then stored
in the chemical bonds of the carbohydrates produced by this reaction. Oxygen is the most
important by-product of the process.
Artificial photosynthesis is the term often used to describe engineered solar or photovoltaic
cell systems designed to capture light energy and convert it to electrical energy.
- can address many of the current environmental challenges including air pollution,
climate change, and depletion of finite resources
A few producers, mostly specialized bacteria, can convert simple inorganic compounds from
their environment into more complex nutrient compounds without using sunlight, through a
process called chemosynthesis.
2. Consumers, or heterotrophs (“other-feeders”) cannot produce the nutrients they need
through photosynthesis or other processes and must obtain their nutrients by feeding on
other organisms (producers or other consumers) or their remains.
- All consumers (including humans) are directly or indirectly dependent on producers for
their food or nutrients.
Types of consumers
1. Primary consumers, or herbivores (plant eaters), are animals such as rabbits,
grasshoppers, deer, and zooplankton that eat producers, mostly by feeding on green
plants.
2. Secondary consumers, or carnivores (meat eaters), are animals such as spiders,
hyenas, birds, frogs, and some zooplankton-eating fish, all of which feed on the flesh of
herbivores.
3. Third- and higher-level consumers are carnivores such as tigers, wolves, mice-eating
snakes, hawks, and killer whales (orcas) that feed on the flesh of other carnivores.
4. Omnivores such as pigs, foxes, cockroaches, and humans, play dual roles by feeding on
both plants and animals.
5. Decomposers, primarily certain types of bacteria and fungi, are consumers that release
nutrients from the dead bodies of plants and animals and return them to the soil, water,
and air for reuse by producers. They feed by secreting enzymes that speed up the
breakdown of bodies of dead organisms into nutrient compounds such as water, carbon
dioxide, minerals, and simpler organic compounds.
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
6. Detritus feeders, or detritivores, feed on the wastes or dead bodies of other
organisms, called detritus (“di-TRI-tus,” meaning debris). Examples include small
organisms such as mites and earthworms, some insects, catfish, and larger scavenger
organisms such as vultures.
In summary, some organisms produce the nutrients they need, others get their nutrients by
consuming other organisms, and still others recycle the nutrients in the wastes and remains of
organisms so that producers can use them again.
Question 3
When you had your most recent meal, were you an herbivore, a carnivore, or an omnivore?
Respiration is the process by which the chemical energy stored through photosynthesis is
ultimately released to do work in plants and other organisms (from bacteria to plants and
animals).
- Producers, consumers, and decomposers use the chemical energy stored in glucose and
other organic compounds to fuel their life processes by respiration.
Respiration is what may be called described chemically as an oxidation-reduction or redox
reaction.
▪
Oxidation:
C(H2O) + H2O → CO2 + 4 H+ + 4e−
Reduction:
O2 + 4e− + 4 H+ → 2 H2O
Aerobic respiration - uses oxygen to convert glucose (or other organic nutrient molecules)
back into carbon dioxide and water.
glucose + oxygen → carbon dioxide + water + energy
C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + energy
-
▪
Some bacteria rely exclusively on oxygen as an electron acceptor and cannot grow in the
absence of it (termed obligate or strict aerobes or simply aerobes)
Anaerobic respiration, or fermentation - breaking down glucose (or other organic
compounds) in the absence of oxygen
- end products of this process are compounds such as methane gas (CH4, the main
component of natural gas), ethyl alcohol (C2H6O), acetic acid (C2H4O2, the key
component of vinegar), and hydrogen sulfide (H2S, when sulfur compounds are
broken down).
Note that all organisms get their energy from aerobic or anaerobic respiration but only plants
carry out photosynthesis.
Ecosystems Have Two Major Food Chains
Energy fixed by plants is the base that the rest of life on Earth depends on. This energy stored by
plants is passed along through the ecosystem in a series of steps of eating and being eaten known as a food chain.
Feeding relationships within a food chain are defined in terms of trophic or consumer levels.
▪ first trophic level belongs to the primary producers
- producers, most often plants, assimilate simple chemicals and utilize the sun’s
energy to produce and store complex, energy-rich compounds that provide an
organism with substance and stored energy
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
▪
the second level to the herbivores (first-level consumers)
- organisms that eat plants, extracting energy and chemical building blocks to make
more complex substances are primary consumers or herbivores.
▪
the higher levels to the carnivores (second-level consumers)
- secondary consumers or carnivores consume herbivores
Within any ecosystem there are two major food chains – the grazing food chain and the
detrital food chain – shown by Figure 4.
Figure 4: generalized model of trophic structure and energy flow through an ecosystem
•
•
•
Orange arrows linking trophic levels represent the flow of energy associated
with ingestion.
Blue arrows from each trophic level represent the loss of energy through
respiration.
Brown arrows represent a combination of dead organic matter (unconsumed
biomass) and waste products (feces and urine).
First-level consumers
Grazing food chain
Cattle grazing on pastureland,
deer browsing in the forest,
insects feeding on leaves in the
forest canopy, or zooplankton
feeding on phytoplankton in the
water column
Detrital food chain
variety of invertebrates - such as
snails, beetles, millipedes, and
earthworms, as well as fungi and
bacteria
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
Sources of energy
Unidirectional
- net primary production
providing the energy source
for herbivores, herbivores
providing the energy for
carnivores, and so on
Not unidirectional
- waste materials and dead
organic matter (organisms)
in each of the consumer
trophic levels are “recycled,”
returning as an input to the
dead organic matter box at
the base of the detrital food
chain
Question 4
What would happen to an ecosystem if (a) all its decomposers and detritus feeders were
eliminated, (b) all its producers were eliminated, or (c) all of its insects were eliminated?
Could a balanced ecosystem exist with only producers and decomposers and no consumers
such as humans and other animals? Explain.
Energy Flow and Nutrient Cycling Sustain Ecosystems and the Biosphere
Ecosystems and the biosphere are sustained through a combination of one-way energy flow from
the sun through these systems and nutrient cycling of key materials within them – two
important natural services that are components of the earth’s natural capital.
These two scientific principles of sustainability arise from the structure and function of
natural ecosystems, the law of conservation of matter, and the two laws of thermodynamics
Figure 5: Energy Flow and Nutrient Cycling
Decomposers and detritus feeders, many of which are microscopic organisms, are the key to
nutrient cycling because they break down organic matter into simpler nutrients that can be
reused by producers.
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
-
-
Without decomposers and detritus feeders, there would be little, if any, nutrient cycling
and the planet would be overwhelmed with plant litter, dead animal bodies, animal
wastes, and garbage.
Most life as we know it could not exist because the nutrients stored in such wastes and
dead bodies would be locked up and unavailable for use by other organisms.
Question 5
1. How does the continuous, directional flow of water influence the cycling of nutrients in
stream ecosystems?
2. What mechanism functions to conserve nutrients in estuary ecosystems?
III. BIOGEOCHEMICAL CYCLES
The internal cycling of nutrients within the ecosystem is driven by the processes of net primary
productivity and decomposition. Though internal cycling of nutrients is mediated by biological
processes, many chemical reactions take place in abiotic components of the ecosystem.
For examples:
- Weathering of rocks and minerals releases certain elements into the soil and water,
making them available for uptake by plants
- Energy from lightning produces small amounts of ammonia (NH3) from molecular
nitrogen and water in the atmosphere, providing an input of nitrogen to aquatic and
terrestrial ecosystems
- Sedimentation of calcium carbonate in marine environments remove elements from the
active process of internal cycling
All nutrients flow from the nonliving to the living and back to the nonliving components of the
ecosystem in a more or less cyclic path known as the biogeochemical cycle (from bio, “living”;
geo for the rocks and soil; and chemical for the processes involved).
Figure 6: A generalized representation of the biogeochemical cycle of an ecosystem
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
There are two basic types of biogeochemical cycles: and sedimentary.
▪ Gaseous cycles
o the main pools of nutrients are the atmosphere and the oceans and it is distinctly
global
o gases most important for life are nitrogen, oxygen, and carbon dioxide
▪ Sedimentary cycle
o main pool is the soil, rocks, and minerals
o available forms occur as salts dissolved in soil water or in lakes, streams, and seas
Gaseous and sedimentary cycles involve biological and nonbiological processes. Both cycles are
driven by the flow of energy through the ecosystem, and both are tied to the water cycle. Water is
the medium that moves elements and other materials through the ecosystem. Without the
cycling of water, biogeochemical cycles would cease.
Five chemicals are of particular importance in environmental engineering: C, O, N, P and S. In
addition, the hydrologic cycle is of interest because it plays an important role in moving
chemical elements through the ecosphere.
1. Oxygen and Carbon Cycles
The oxygen cycle and carbon cycle are closely linked through the processes of photosynthesis
and respiration.
- Photosynthesis is the primary source term in the oxygen cycle and the origin of the
organic carbon converted to carbon dioxide in the carbon cycle. It is carried out by
plants and some bacteria.
- Respiration is the major sink term in the oxygen cycle and is responsible for the
conversion of organic carbon to carbon dioxide in the carbon cycle. It is carried out by
all organisms, including those that photosynthesize.
Carbon, a basic constituent of all organic compounds, is involved in the fixation of energy by
photosynthesis. We often express ecosystem productivity in terms of grams of carbon fixed per
square meter per year. Figure 7 shows the cycling of carbon through a terrestrial ecosystem.
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
Figure 7: The carbon cycle as it occurs in both terrestrial and aquatic ecosystems
The rate of uptake of CO2 is driven by two main cycles: the solubility and biological pumps.
▪ Solubility pump
- CO2 dissolution is enhanced in colder waters, driving dissolution of CO2 from the
atmosphere into the waters. Because these colder waters are denser than the warmer
waters below, the colder waters tend to sink, taking with them CO2.
- Much of this CO2 is “lost” to deep waters, keeping surface waters lower in CO2 and
driving dissolution from the atmosphere
▪
Biological pump
- Involves phytoplankton, zooplankton and their predators, and bacteria
- As these organisms die and settle into deeper regions of ocean, bound CO2 finds its
way into the ocean depths with the fecal matter of these organisms. Thus, the depths
of the ocean become a CO2 sink, releasing carbon mainly through “upwelling” of
water, diffusion across the thermocline, and seasonal, wind-driven mixing, which
brings the deep water to the surface.
- This mixing of the deeper waters returns nutrients and carbon to the ocean surface,
continuing the cycle of photosynthesis and respiration.
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
The interplay of photosynthesis and respiration plays a key role in regulating ecosystem energy
balances and in maintaining the oxygen levels required by life in aquatic environments.
2. The Nitrogen Cycle
Nitrogen is an essential constituent of protein, which is a building block of all living tissue.
Nitrogen is generally available to plants in only two chemical forms: ammonium (NH4+) and
nitrate (NO3−). Thus, although Earth’s atmosphere is almost 80 percent nitrogen gas, it is in a
form (N2) that is not available for uptake (assimilation) by plants.
As a result of their association with bacteria and plants, many features of the nitrogen cycle are
linked with the oxygen and carbon cycles.
Nitrogen enters the ecosystem via two pathways. (Figure 8)
▪
Atmospheric fixation or deposition
- In wet fall – such as rain, snow or even cloud and fog droplets – and in dry fall, such
as aerosols and particulates
- Nitrogen in this pathway is supplied in a form that is already available for uptake by
plants.
▪
Nitrogen fixation
1.
High-energy fixation
o Cosmic radiation, meteorite trails, and lightning provide the high energy needed to
combine nitrogen with the oxygen and hydrogen of water.
o The resulting ammonia and nitrates are carried to Earth’s surface in rainwater.
Estimates suggest that less than 0.4 kg N/ha comes to Earth annually in this manner.
o About two-thirds of this amount is deposited as ammonia and one-third as nitric
acid (HNO3).
2. Biological
o This fixation is accomplished by symbiotic bacteria living in mutualistic association
with plants, by free living aerobic bacteria, and by cyanobacteria (blue-green algae)
o Fixation splits molecular nitrogen (N2) into two atoms of free N. The free N atoms
then combine with hydrogen to form two molecules of ammonia (NH3)
o The process of fixation requires considerable energy. To fix 1 g of nitrogen, nitrogenfixing bacteria associated with the root system of a plant must expend about 10 g of
glucose, a simple sugar produced by the plant in photosynthesis.
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MODULE 1 – Ecological Concepts and Sustainability
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Figure 8: The nitrogen cycle in terrestrial and aquatic ecosystems
In addition to atmospheric deposition, NH4+ occurs in the soil as a product of microbial
decomposition of organic matter wherein NH3 is released as a waste product of microbial
activity. This process is called ammonification (see Figure 8).
Most soils have an excess of H+ (slightly acidic) and the NH3 is rapidly converted to ammonium
(NH4+). Interestingly, because NH3 is a gas, the transfer of nitrogen back to the atmosphere
(volatilization) can occur in soils with a pH close to 7 (neutral) – a low concentration of H+ ions
to convert ammonia to ammonium. Volatilization can be especially pronounced in agricultural
areas where both nitrogen fertilizers and lime (to decrease soil acidity) are used extensively.
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Figure 9: Bacterial processes involved in nitrogen cycling
Mechanisms of nitrogen cycle
The ammonia released from the organic compounds, plus that from other sources such as
industrial wastes and agricultural runoff (e.g., fertilizers and manure) is oxidized to nitrate
(NO−3 ) by a special group of nitrifying bacteria in a two-step process called nitrification:
4NH+4 +6O2
4NO-2 + 2O2
Nitrosomonas sp
Nitrobacter sp
4NO-2 + 8H+ +4H2O
4NO-3
Nitrogen cycles from nitrate to organic nitrogen, to ammonia, and back to nitrate as long as
the water remains aerobic.
Under anoxic conditions, for example, in anaerobic sediments, when algal decomposition
has depleted the oxygen supply, nitrate is reduced by bacteria to nitrogen gas (N2) and lost
from the system in a process called denitrification.
2NO-3 + organic carbon
N 2 + CO2 + H2O
Since nitrate is an important nutrient supporting plant growth, it may be the limiting nutrient
in some systems, especially coastal marine environment. Discharges to surface waters can create
nuisance algal growth and attendant water-quality problems such as oxygen depletion.
3. Phosphorus cycle
Phosphorus occurs in only minute amounts in the atmosphere. Therefore, the phosphorus cycle
can follow the water (hydrological) cycle only part of the way – from land to sea (Figure 10).
Because phosphorus lost from the ecosystem in this way is not returned via the biogeochemical
cycle, phosphorus is in short supply under undisturbed natural conditions. The natural scarcity
of phosphorus in aquatic ecosystems is emphasized by the explosive growth of algae in water
(eutrophication) receiving heavy discharges of phosphorus-rich wastes.
Phosphorus in unpolluted waters is imported through dust in precipitation or via the
weathering of rock. Phosphorus is normally present in watersheds in extremely small amounts,
usually existing dissolved as inorganic orthophosphate, suspended as organic colloids, adsorbed
onto particulate organic and inorganic sediment, or contained in organic water.
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In marine and freshwater ecosystems, the phosphorus cycle moves through three states:
particulate organic phosphorus, dissolved organic phosphates, and inorganic phosphates.
Figure 10: The phosphorus cycle in aquatic and terrestrial ecosystems
The main reservoirs of phosphorus are rock and natural phosphate deposits. Phosphorus is
released from these rocks and minerals by weathering, leaching, erosion, and mining for use as
agricultural fertilizers.
In most soils, only a small fraction of the total phosphorus is available to plants. The only
significant form of phosphorus available to plants and algae is the soluble reactive inorganic
orthophosphate species (HPO2−4, PO3−4, etc.) that are incorporated into organic compounds.
When phosphorus is mined and incorporated into cleaning agents and fertilizers,
biogeochemical cycle (the routing of the element through the environment) is vastly
accelerated.
4. Sulfur cycle
The sulfur cycle has both sedimentary and gaseous phases (Figure 11). In the long-term
sedimentary phase, sulfur is tied up in organic and inorganic deposits, released by weathering
and decomposition, and carried to terrestrial ecosystems in salt solution. The gaseous phase of
the cycle permits sulfur circulation on a global scale.
Sulfur enters the atmosphere from several sources: the combustion of fossil fuels, volcanic
eruptions, exchange at the surface of the oceans, and gases released by decomposition.
It enters the atmosphere initially as hydrogen sulfide (H2S), which quickly interacts with oxygen
to form sulfur dioxide (SO2). Atmospheric sulfur dioxide, soluble in water, is carried back to the
surface in rainwater as weak sulfuric acid (H2SO4).
Sulfur in a soluble form is taken up by plants and incorporated through a series of metabolic
processes, starting with photosynthesis, into sulfur-bearing amino acids. From the primary
producers, sulfur in amino acid is transferred to consumers.
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Excretion and death carry sulfur from living material back to the soil and to the bottom of ponds,
lakes, and seas, where bacteria release it as hydrogen sulfite or sulfate.
Figure 11: The sulfur cycle
Like the oxygen and nitrogen cycle, the sulfur cycle is to a large extent microbially mediated
and thus linked to the carbon cycle.
- colorless sulfur bacteria reduce hydrogen sulfide to elemental sulfur and then oxidizes
it to sulfuric acid.
- Green and purple bacteria, in the presence of light, use hydrogen sulfide during
photosynthesis.
o Purple bacteria, found in salt marshes and in the mudflats of estuaries, transform
hydrogen sulfide into sulfate, which is then recirculated and taken up by
producers or used by bacteria that further transform the sulfates
o Green bacteria can transform hydrogen sulfide into elemental sulfur
Sulfur, in the presence of iron and under anaerobic conditions, will precipitate as ferrous sulfide
(FeS2).
- highly insoluble in neutral and low pH (acidic) conditions, and it is firmly held in mud
and wet soil
- Sedimentary rocks containing ferrous sulfide, called pyritic rocks, may overlie coal
deposits. When exposed to air during deep and surface mining for coal, the ferrous
sulfide reacts with oxygen. In the presence of water, it produces ferrous sulfate (FeSO4)
and sulfuric acid.
Sulfur in pyritic rocks, is exposed to weathering by human activities, discharges sulfuric acid,
ferrous sulfate, and other sulfur compounds into aquatic ecosystems. These compounds destroy
aquatic life. In addition, the low pH of the water dissolves rocks and minerals, releasing hardness
and total dissolved solids.
Question 6
1. Describe how human activities are altering each of the nutrient cycles.
2. Describe how phosphorus availability could control nitrogen uptake.
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IV. ENVIRONMENTAL LAWS AND REGULATIONS
Environmental pollution− supported by a complex web of laws and regulations which are
implemented and enforced by numerous individuals, agencies, lawmakers and courts.
Environmental laws − establish broad goals for environmental quality; set standards of behavior
for individuals, industry, and government; create agencies to monitor the environment and to
oversee the actions of other groups; and establish penalties for failure to adhere to law.
Environmental agencies − governmental units charged with monitoring and protecting the
environment
Environmental regulations are not laws but are specific rules that have the power of law.
Regulations are created by environmental agencies to protect existing environmental quality; to
limit present or future discharges of pollutants from industry, municipality, and individuals;
and to provide the legal means and authority to monitor the actions of the other groups and
enforce compliance with the regulation.
International Concern for Environment
The international concern for environment was first immerged in the United Nations
Conference on Human Environment in Stockholm in June 1972 where a declaration was made
that
1. Man has the fundamental right to freedom, equality and adequate conditions of life in
an environment of quality that permits a life of dignity and well-being.
2. Man bears a solemn responsibility to protect and improve the environment for present
and future generations.
This declaration was adopted by the United Nations General Assembly in December 1972 and
June 5 was declared as the World Environment Day.
The conference on Security and Co-operation in Europe on August 1, 1975, announced that
“Environmental protection was important both for the well-being of the people and economic
progress of the country”.
Environmental Protection Laws in the Philippines
1. Constitutional mandates on environment
2. Republic Acts (RA) enacted for the protection and management of the environment
V. SUSTAINABILITY AND CRADLE-TO-CRADLE DESIGN
A. Environmental Problems, Their Causes, and Sustainability
What Is an Environmentally Sustainable Society?
The environment is everything around us. It includes all of the living and the nonliving things
with which we interact. And it includes a complex web of relationships that connect us with one
another and with the world we live in.
Sustainability is the ability of the earth’s various natural systems and human cultural systems
and economies to survive and adapt to changing environmental conditions indefinitely.
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Natural Capital = Natural Resources + Natural Services
A critical component of sustainability is natural capital − the natural resources and natural
services that keep us and other forms of life alive and support our economies.
▪
▪
▪
Natural capital is supported by solar capital: energy from the sun. Take away solar
energy, and all-natural capital would collapse.
Solar energy warms the planet and supports photosynthesis—a complex chemical
process that plants use to provide food for themselves and for us and most other animals
This direct input of solar energy also produces indirect forms of renewable solar energy
such as wind, flowing water, and biofuels made from plants and plant residues.
Natural resources are materials and energy in nature that are essential or useful to humans.
These resources are often classified as renewable (such as air, water, soil, plants, and wind) or
nonrenewable (such as copper, oil, and coal).
Natural services are functions of nature, such as purification of air and water, which support
life and human economies. Ecosystems provide us with these essential services at no cost.
▪
One vital natural service is nutrient cycling, the circulation of chemicals necessary for
life, from the environment (mostly from soil and water) through organisms and back to
the environment
o For example, topsoil, the upper layer of the earth’s crust, provides the nutrients
that support the plants, animals, and microorganisms that live on land; when
they die and decay, they resupply the soil with these nutrients. Without this
service, life as we know it could not exist.
A second component of sustainability is to recognize that many human activities can degrade
natural capital by using normally renewable resources faster than nature can renew them. For
example, in parts of the world, we are clearing mature forests much faster than nature can
replenish them. We are also harvesting many species of ocean fish faster than they can replenish
themselves.
▪ Environmental scientists search for solutions to problems such as the degradation of
natural capital.
o solutions could require government laws and regulations
The ultimate goal is an environmentally sustainable society—one that meets the
current and future basic resource needs of its people in a just and equitable manner
without compromising the ability of future generations to meet their basic needs.
Question 7
Write your own definition of sustainable development as it applies to your engineering
profession. Explain its appropriateness and applicability in 2 – 3 sentences.
B. What Is Pollution and What Can We Do about It?
Pollution is any in the environment that is harmful to the health, survival, or activities of
humans or other organisms.
▪ Pollutants can enter the environment naturally, such as from volcanic eruptions, or
through human activities, such as burning coal and gasoline and discharging chemicals
into rivers and the ocean.
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Sources of pollutants:
1. Point sources are single, identifiable sources.
o Examples are the smokestack of a coal-burning power or industrial plant
2. Nonpoint sources are dispersed and often difficult to identify.
o Examples are pesticides blown from the land into the air and the runoff of
fertilizers and pesticides from farmlands, lawns, gardens, and golf courses into
streams and lakes.
❖ It is much easier and cheaper to identify and control or prevent pollution from point
sources than from widely dispersed nonpoint sources.
Types of pollutants:
1. Biodegradable pollutants are harmful materials that can be broken down by natural
processes.
o Examples are human sewage and newspapers.
2. Nondegradable pollutants are harmful materials that natural processes cannot break
down.
o Examples are toxic chemical elements such as lead, mercury, and arsenic
Three types of unwanted effects of pollutants
▪ First, they can disrupt or degrade life-support systems for humans and other species
▪ Second, they can damage wildlife, human health, and property
▪ Third, they can create nuisances such as noise and unpleasant smells, tastes, and sights.
Clean Up Pollution or Prevent It?
Pollution cleanup, or output pollution control
- involves cleaning up or diluting pollutants after they have been produced.
Three problems on pollution cleanup
First, it is only a temporary bandage as long as population and consumption levels grow without
corresponding improvements in pollution control technology.
Example: adding catalytic converters to car exhaust systems has reduced some forms of air
pollution. At the same time, increases in the number of cars and the total distance each car
travels have reduced the effectiveness of this cleanup approach.
Second, cleanup often removes a pollutant from one part of the environment only to cause
pollution in another.
Example: we can collect garbage, but the garbage is then burned (perhaps causing air pollution
and leaving toxic ash that must be put somewhere), dumped on the land (perhaps causing water
pollution through runoff or seepage into groundwater), or buried (perhaps causing soil and
groundwater pollution).
Third, once pollutants become dispersed into the environment at harmful levels, it usually costs
too much or is impossible to reduce them to acceptable levels.
Pollution prevention, or input pollution control, which reduces or eliminates the
production of pollutants.
Preventing pollution is more effective and less costly than cleaning up pollution.
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C. Why Do We Have Environmental Problems?
Causes of Environmental Problems
1. population growth
2. wasteful and unsustainable resource use
3. poverty
4. exclusion of environmental costs of resource use from the market prices of goods and
services
5. attempts to manage nature with insufficient knowledge
Poverty Has Harmful Environmental and Health Effects
Poverty occurs when people are unable to meet their basic needs for adequate food, water,
shelter, health, and education.
Desperate for short-term survival, some of these people deplete and degrade forests,
soil, grasslands, fisheries, and wildlife, at an ever-increasing rate. They do not have
the luxury of worrying about long-term environmental quality or sustainability.
While poverty can increase some types of environmental degradation, the reverse is
also true. Pollution and environmental degradation have a severe impact on the poor
and can increase poverty. Consequently, many of the world’s desperately poor
people die prematurely from several preventable health problems.
Affluence Has Harmful and Beneficial Environmental Effects
-
The lifestyles of many affluent consumers in developed countries and in rapidly
developing countries such as India and China are built upon high levels of consumption
and unnecessary waste of resources. Such affluence is based mostly on the assumption fueled by mass advertising - that buying more and more things will bring happiness.
-
On the other hand, affluence can lead people to become more concerned about
environmental quality. It also provides money for developing technologies to reduce
pollution, environmental degradation, and resource waste.
Prices Do Not Include the Value of Natural Capital
▪
When companies use resources to create goods and services for consumers, they are
generally not required to pay the environmental costs of such resource use.
Examples:
o
o
Fishing companies pay the costs of catching fish but do not pay for the depletion
of fish stocks.
Timber companies pay for clear-cutting forests but not for the resulting
environmental degradation and loss of wildlife habitat.
▪
The primary goal of these companies is to maximize their profits, so they do not
voluntarily pay these harmful environmental costs or even try to assess them, unless
required to do so by government laws or regulations.
▪
As a result, the prices of goods and services do not include their harmful environmental
costs. Thus, consumers are generally not aware of them and have no effective way to
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evaluate the resulting harmful effects on the earth’s life-support systems and on their
own health.
▪
Governments give companies tax breaks and payments called subsidies to assist them in
using resources to run their businesses. This helps to create jobs and stimulate
economies, but it can also result in degradation of natural capital, again because the
value of the natural capital is not included in the market prices of goods and services.
People Have Different Views about Environmental Problems and Their Solutions
Environmental worldview is a set of assumptions and values reflecting how you think the
world works and what you think your role in the world should be.
Environmental ethics, which are our beliefs about what is right and wrong with how we treat
the environment
Ethical questions:
• Why should we care about the environment?
• Are we the most important beings on the planet or are we just one of the earth’s millions
of different forms of life?
• Do we have an obligation to see that our activities do not cause the premature extinction
of other species? Should we try to protect all species or only some? How do we decide
which species to protect?
• Do we have an ethical obligation to pass on to future generations the extraordinary
natural world in a condition at least as good as what we inherited?
• Should every person be entitled to equal protection from environmental hazards
regardless of race, gender, age, national origin, income, social class, or any other factor?
Question 8
1. How would you answer each of the questions above? Compare your answers with those
of your classmates. Record your answers and, at the end of this course, return to these
questions to see if your answers have changed.
2. Explain why you agree or disagree with the following propositions:
a. Stabilizing population is not desirable because, without more consumers, economic
growth would stop.
b. The world will never run out of resources because we can use technology to find
substitutes and to help us reduce resource waste
3. List three ways in which you make your lifestyle more environmentally sustainable.
D. What Are Four Scientific Principles of Sustainability?
Nature has sustained itself for billions of years by using solar energy, biodiversity,
population control, and nutrient cycling—lessons from nature that we can apply to our
lifestyles and economies.
▪
Reliance on Solar Energy: the sun (solar capital) warms the planet and supports
photosynthesis used by plants to provide food for themselves and for us and most other
animals.
▪
Biodiversity (short for biological diversity): the astounding variety of different organisms,
the genes they contain, the ecosystems in which they exist, and the natural services they
provide have yielded countless ways for life to adapt to changing environmental
conditions throughout the earth’s history.
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▪
Population Control: competition for limited resources among different species places a
limit on how much their populations can grow.
▪
Nutrient Cycling: natural processes recycle chemicals that plants and animals need to
stay alive and reproduce (Figure below). There is little or no waste in natural systems.
natural systems.
These four interconnected principles of sustainability are derived from learning how nature has
sustained a variety of life forms on the earth for about 3.56 billion years.
- The top left oval shows sunlight stimulating the production of vegetation in the arctic
tundra during its brief summer (solar energy) and the top right oval shows some of the
diversity of species found there during the summer (biodiversity).
- The bottom right oval shows arctic gray wolves stalking a caribou during the long cold
winter (population control). The bottom left oval shows arctic gray wolves feeding on
their kill. This, plus huge numbers of tiny decomposers that convert dead matter to soil
nutrients, recycle all materials needed to support the plant growth shown in the top left
and right ovals (nutrient cycling).
Using the four scientific principles of sustainability to guide our lifestyles and
economies could help us bring about an environmental or sustainability revolution
during your lifetime.
Shifts involved in bringing about this new cultural change by learning how to live more
sustainably
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Question 9
Which three of these shifts do you think are most important? Why?
E. Engineers and Sustainability
Sustainability
If in our system view, we look beyond the simple idea of controlling pollution to the larger idea
of sustaining our environment, we see that there are better solutions for our pollution problems.
1. Pollution prevention by the minimization of waste production
2. LCA of our production techniques to include built-in features for extraction and reuse
of materials
3. Selection of materials and method that have a long life
4. Selection of manufacturing methods & equipment that minimize energy and water
consumption
How do we maintain our ecosystem in the light of major depletion of our natural resources?
Environmental engineers use their design training to be proactive and preemptive in the
development of solutions.
▪ As they move away from a focus on end-of-pipe treatment and even beyond pollution
prevention through engineering controls, they will move toward the use of design to
prevent problems from the start.
▪ Emerging fields such as green chemistry, green engineering, and design for the
environment, will help environmental and other engineers develop sustainable products
and foster sustainable materials management.
Green Engineering
▪ principles and frameworks to guide the development of solutions
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▪
65 engineers and scientists convened in Sandestin, Florida to develop a set of principles
for green engineering
Definition of Green Engineering (U.S. Environmental Protection Agency – EPA)
- the design, commercialization, and use of processes and products [that] are feasible
and economical while minimizing 1) generation of pollution at the source and 2) risk
to human health and the environment
Principles of Green Engineering
- Sandestin Principles for Sustainable Engineering
1.
2.
3.
4.
5.
6.
7.
8.
9.
Engineer processes and products holistically, use systems analysis, and integrate
environmental impact assessment tools.
Conserve and improve natural ecosystems while protecting human health and wellbeing.
Use life-cycle thinking in all engineering activities.
Ensure that all material and energy inputs and outputs are as inherently safe and benign
as possible.
Minimize depletion of natural resources.
Strive to prevent waste.
Develop and apply engineering solutions, while being cognizant of local geography,
aspirations, and cultures.
Create engineering solutions beyond current or dominant technologies; improve,
innovate, and invent (technologies) to achieve sustainability.
Actively engage communities and stakeholders in development of engineering
solutions.
Sustainable Engineering
▪ transforms existing engineering disciplines and practices into those that promote
sustainability
▪ incorporates the development and implementation of technologically and economically
viable products, processes, and systems that promote human welfare, while protecting
human health and elevating the protection of the biosphere as a criterion in engineering
solutions
F. Sustainability and Cradle-To-Cradle Design
Sustainable materials management (SMM) has emerged as “an approach to promote
sustainable materials use, integrating actions targeted at reducing negative
environmental impacts and preserving natural capital throughout the life-cycle of
materials, taking into account economic efficiency and social equity.”
The Natural Step
- a framework for sustainability from Sweden through the efforts of Dr. Karl-Henrik
Robèrt, a leading Swedish oncologist, in 1989
- provides a set of four system conditions that define a sustainable society based on
the laws of thermodynamics and natural cycles
The Natural Step System Conditions consider the Earth as a closed system for materials and as
an open system for energy that sustains life through a complex interactive network of material
cycles that uses solar energy to counteract the tendency of materials to dissipate and otherwise
increase in entropy.
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For a society to be sustainable, nature must not be subjected to the following systematically
increasing processes:
1. Extracting concentrations of substances from the Earth’s crust.
- This condition refers to the extraction of minerals and fossil fuels. Substances that
are scarce in nature should be substituted with those that are more abundant. Mined
materials should be used efficiently and recycled, and dependence on fossil fuels
should be systematically reduced.
2. Building up concentrations of human-made compounds in nature.
- This condition refers to the manufacture of persistent and unnatural compounds.
Persistent and unnatural compounds should be replaced with those that are
normally abundant and or that break down completely and easily in nature. All
substances produced by society should be used efficiently.
3. Utilizing renewable resources at rates faster than they are regenerated and reducing the
productive capacity of nature.
- This condition refers to the use of natural resources. Resources should be drawn only
from well managed ecosystems, systematically pursuing the most productive and
sustainable uses both of those resources and land, and exercising caution in all kinds
of modification of nature.
And in that society:
4. People are able to meet their needs worldwide.
- This condition means using all of our resources efficiently, effectively, fairly and
responsibly so that the needs of all people, including the future needs of people who
are not yet born, stand the best chance of being met.
Ecological aspects of The Natural Step System Conditions
Materials flow in a closed system comprised of two loops. The outer loop represents the cycling
of materials within earth’s ecosystems. The inner loop represents cycling within the
industrial/economic system.
- Arrow 1 represents the extraction of natural resources for use in the
industrial/economic system. In a sustainable society, the rate of natural resource
extraction equals the rate of regeneration.
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-
-
Arrows 2 and 3 represent the extraction and resettling of materials from the earth’s
crust, primarily fossil fuel and mined materials. In a sustainable society, material
extraction from the earth’s crust will be displaced by the use of recycled and
recyclable materials.
Arrows 4 and 5 represent substances that flow from the industrial/economic system
to the greater ecosystem. Substances that assimilate quickly without harm are
represented by Arrow 4. Arrow 5 represents substances that are toxic, persistent,
bio-accumulative, or otherwise cause harm to humans or the environment. In a
sustainable society, Arrow 5 will disappear.
To address the first three, strategies include both dematerialization (using less resources
to accomplish the same task), substitution of alternatives, more efficient use of materials
and the 3 Rs and 1 C: Reduce, Reuse, Recycle and Compost.
Illustrating the practical way of addressing the principles:
1. What We Take from the Earth: Mining and Fossil Fuels – Avoid “systematically
increasing concentrations of substances extracted from the earth’s crust.” Simply, we need
to use renewable energy and nontoxic, reusable materials to avoid the spread of hazardous
mined metals and pollutants. Why? Mining and burning fossil fuels release a wide range of
substances that do not go away, but rather, continue to build up and spread in our
ecosphere. Nature has adapted over millions of years to specific amounts of these materials.
Cells don't know how to handle significant amounts of lead, mercury, radioactive materials
and other hazardous compounds from mining, often leading to learning disabilities,
weakening of immune systems and improper development of the body. The burning of fossil
fuels generates dangerous levels of pollutants contributing to smog, acid rain and global
climate change.
Action: We can support policies and take action to reduce our overall energy use. We can drive
less, carpool, use public transportation, ride bikes or walk. We can conserve energy through
energy-efficient lighting, proper insulation, passive solar, and reduced heating and cooling. We
can support a shift to renewable energy such as solar and wind power instead of nuclear, coal
or petroleum. We can also decrease our use of mined metals and minerals through recycling,
reuse and preferably, reduced consumption. We also can avoid chemical fertilizers.
2. What We Make: Chemicals, Plastics and Other Substances – Nature must not “be
subject to systematically increasing concentrations of substances produced by society.”
Simply, we need to use safe, biodegradable substances that do not cause the spread of toxins
in the environment. Why? Since World War II, our society has produced more than 85,000
chemicals, such as DDT and PCBs. Many of these substances do not go away, but rather,
spread and bio-accumulate in nature and the fat cells of animals and humans. Cells don't
know how to handle significant amounts of these chemicals, often leading to cancer,
hormone disruption, improper development, birth defects and long-term genetic change.
Action: We can support green procurement policies and use non-toxic natural cleaning
materials and personal care products. We can decrease our use of plastics and reuse the ones
we have, such as plastic bags, plates, cups and eating utensils. We can stop using CFCs and other
ozone-depleting substances. We can use safe, natural pest control in our schools, parks, homes,
lawns and gardens. We can support farmers in becoming sustainable and eliminating hazardous
pesticides by voting with our dollars for certified organic food and clothing. We can support the
elimination of factory farm feedlots and manure ponds that cause air and water pollution.
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3. What We Do to the Earth: Biodiversity and Ecosystems – Nature must not “be subject
to degradation by physical means.” Simply, we need to protect our soils, water and air, or
we won't be able to eat, drink or breathe. Why? Forests, soils, wetlands, lakes, oceans and
other naturally productive eco-systems provide food, fiber, habitat and oxygen, waste
handling, temperature moderation and a host of other essential goods and services. For
millions of years, they have been purifying the planet and creating a habitat suitable for
human and other life. When we destroy or deplete these systems, we endanger both our
livelihoods and the likelihood of human existence.
Action: We can purchase certified, sustainably-harvested forest products rather than
destroying rainforests. We can reduce or eliminate our consumption of products that are not
sustainably harvested, such as certain types of fish and seafood. We can shop with reusable bags
rather than using more paper bags. We can decrease our use of water and use composting toilets
that return valuable nutrients to the earth. We can fight urban sprawl and encourage the
cleaning up of brown fields and other contaminated sites. We can support smart growth and
safeguard endangered species by protecting wildlife habitat.
4. Meeting Basic Human Needs - "Human needs are met worldwide.” Simply, we can use
less stuff and save money while meeting the needs of every human on this planet. Why? The
US makes up only 4% of the world's population but consumes about 25% of its resources.
The people living in the lowest 20% by income receive only 1.4% of the world's income. Just
to survive, they see no choice but to cut down rainforests, sell endangered species, and use
polluting energy sources.
Action: Make business, government and nonprofits aware that we can achieve the ten-fold
increase in efficiency needed to become sustainable, and, in some cases, a 100-fold increase in
productivity that will save money, create jobs and reduce waste as part of a new Industrial
Revolution. We can encourage discussions about basic needs, ask if we really need more stuff,
and design our workplaces, homes and organizations to give us more of what we want (healthy,
attractive and nurturing environments) and less of what we don't want (pollution, stress and
expense).
G. Cradle-to-Cradle Design
Just as in natural systems where one organism’s waste becomes food for another, cradle-tocradle design applies the same concept to the design of human industry.
Cradle-to-cradle design defines two metabolisms within which materials are conceived as
nutrients circulating benignly and productively through metabolisms. Biological nutrients cycle
within biological metabolisms, and technical nutrients cycle within technical metabolisms.
Biological metabolism
▪ the system of natural processes that supports life
▪ Biological processes are cyclical, ultimately fueled by the energy of the sun, and include
the biodegradation (and possibly other forms of degradation) of organic materials and
their incorporation into organisms.
Biological nutrients
▪ Materials that contribute to the productivity of biological metabolisms
▪ They are renewable, degradable, and ecologically benign.
▪ Products of industry made from biological nutrients can be integrated into natural or
engineered biological metabolisms, including water treatment processes and organic
processing systems such as composting or anaerobic digestion.
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▪
▪
The output of biological metabolisms can be resources that engender new biological
nutrients, such as beneficial soil amendments.
Products that are intended for release to the environment should designed as biological
nutrients that are benign for their intended functional use.
Industry can also mimic natural processes by creating technical metabolisms that circulate
technical nutrients.
Technical nutrients
▪ are typically nonrenewable and they are valuable for their performance qualities.
Examples include metals such as copper or aluminum.
▪
▪
▪
When designed in cradle-to-cradle systems, technical nutrients can be recovered and
recycled over and over—without degrading their quality and without harm to
handlers—into similar or dissimilar products.
Technical nutrients can be designed for reuse within a company or between companies
in similar or dissimilar industries, depending on the material.
Products made from technical nutrients should be designed to facilitate material
recovery at its highest value with minimal expenditure of energy and cost.
Cradle-to-cradle design, as described by McDonough and Braungart, uses a model of human
industry based on three design principles derived from natural systems.
1.
Use current solar income
With very few exceptions, life on earth is ultimately fueled by energy from the sun. We are
only beginning to expand our capacity to harness solar energy, directly and indirectly, for
human purposes.
2. Celebrate diversity
Natural systems thrive on richness and diversity. Likewise, industry should promote the
development of diverse products that are fitting for different preferences, cultures,
geographies, and ecosystems
3. Waste equals food
There is no waste in nature. The product of one organism is food or structure for another.
Human systems can also be designed to circulate materials productively, eliminating the
concept of waste.
Question 10
1. Presume you were born into a developing country. Your community’s health and
prosperity are threatened by climate changes caused by anthropogenic CO2 emissions
generated primarily by developed countries. This situation is so extreme that people in
your community do not name their children until they live past 5 years old, since many
die before that age. If you had a chance to talk to an engineer in a developed country,
what would you say?
2. Research two examples of persistent organic pollutants (POPs) and write a short
paragraph that describes each chemical, its most common uses and applications, and its
known or suspected impacts on human health and the environment. What are some
economic, societal, and environmental issues associated with your chemicals?
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MODULE 1 – Ecological Concepts and Sustainability
Engr. Caesar P. Llapitan
Three lessons:
1. it is dangerous to develop models that are too simplistic
2. environmental engineers and scientists must use a multimedia approach and, in
particular, work with multidisciplinary team to solve environmental problems
3. the best solution to environmental pollution is a waste minimization – if waste is not
produced, it does not need to be treated or disposed of
References:
1. Davis, Mackenzie L. and Susan J. Masten. (2014). Principles of Environmental
Engineering and Science, 3rd Edition, McGraw-Hill Co.
2. K. Saravanan, et. al (2005). Principles of Environmental Science and
Technology. New Age International (P) Ltd., Publishers
3. Miller, G. Tyler, Jr. and Scott E. Spoolman (2009). Essentials of Ecology, 5th Edition.
Brooks/Cole, Cengage Learning.
4. Smith, Thomas M. and Robert Leo Smith (2012). Elements of Ecology, 8th Edition.
Pearson Education, Inc
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