ENVIRONMENTAL SYSTEMS Module Code: NG1028M

1
ENVIRONMENTAL SYSTEMSModule Code NG1028M

• Dr Heidi Smith
• Lecture 1 part A Introduction to Systems

2
Lecture outline

• What are environmental systems
• Definitions
• Characteristics
• History of the integrated approach
• Laws of matter and energy
• Types of system
• Equilibrium, feedback and thresholds

3
What is the environment?

• The circumstances, objects or conditions by which
  one is surrounded?
• The aggregate of social and cultural conditions
  that influence the life of an individual or
  community  this has social, political, economic
  and technological dimensions? 
• The complex of climatic, edaphic and biotic
  factors that act upon an organism or an
  ecological community and ultimately determine its
  form and survival?

4
The natural environment?

• Physical
• Lithosphere
• Hydrosphere
• Atmosphere

• Biological
• Biosphere
• Biota - all life forms

NB Biosphere is often used to refer to what we
shall call the Ecosphere, with our biosphere
sometimes simply referred to as biota
5
The ecosphere

• Includes lower atmosphere, all life (biosphere),
  the oceans, soils and solid sediments that
  exchange elements actively with the rest of the
  ecosphere
• Ecosphere is a linked system

6
(No Transcript)
7
What is a System?

• System is a word that we use everyday
• Transport system
• Circulatory system
• Educational system
• Heating system
• So what does a system actually mean?

8

• A System is
• an assembly of parts or components connected
  together in an organised way
• (Bieshon, 1971, Systems. Open University)
• Systems are used by humans in every day life to
  describe the operation of a number of diverse
  phenomena

9
A system is ...
a group of things or parts (called elements) that
work together through a regular set of relations
(called links) within defined limits (called the
system boundary)
(Haggett, 2001, Geography a global synthesis.)

• Within their defined boundaries systems contain
  three types of properties elements, attributes,
  and relationships
• Elements are the things that make up the system
  of interest
• Attributes are the perceived characteristics of
  the elements
• Relationships are descriptions of how the various
  elements (and their attributes) work together to
  carry out some kind of process

10
System characteristics

•  White, Mottershead and Harrison (1992) - a set
  of elements with a set of properties
• All systems have some structure or organization
• They are all to some extent generalisations,
  abstractions or idealisations of the real world
• All function in some way
• There are functional and structural relationships
  between the parts
• Function implies that flows and transfers of
  material occur
• Function requires a driving force or energy
  source
• All systems have some degree of integration

11
Deayon et al. (2000) consider a system to have
the following 4 components

• Reservoirs a repository where something is
  accumulated, stored and potentially passed to
  other elements of the system
• Processes an ongoing activity in the system
  that determines the contents of the reservoirs
  over time.
• Converters system variables that can play
  different roles within a system. Dictate the
  rates at which processes operate and therefore
  the rates at which reservoir contents change
• Interrelationships the intricate connections
  among all components of the system, usually
  expressed as simple mathematical relationships

12
What is useful about systems thinking and
organization for constructing mental images of
our experience of the world?

• The need to organise experiences
• As a general method of approach to working out
  how those systems work
• Useful to ringfence something you want to
  understand, because fences are for convenience
  and are moveable
• Fences can be moved at need - to hold less or
  more, to see from a finer or larger scale than
  before
• It can be modular (can modify sections)
• It has depth (can zoom in and out)
• Connections can be built and broken as needed, or
  as scale or perspective shifts and the modules
  moved around ...

13
An Environmental system?

• An environmental system can be defined as a
  system where life interacts with abiotic factors.
• All involve the capture, movement, storage, and
  use of energy.
• This fact also makes them energy systems.
• Energy is captured in the living components of
  environmental systems
• photosynthesis, biomass consumption, and biotic
  decomposition.
• Energy is also used in environmental processes
  that are strictly abiotic
• solar energy is responsible for wind, weathering,
  and precipitation.

14
An Environmental system?

• Systems vary in size and complexity and in the
  organisational hierarchy
• e.g. biosphere - biome - ecosystem - community -
  population - organism
• Boundaries may be flexible.
• e.g. ecosystem a forest, a single tree, the edge
  of a pond, or the edges of a hectare of grassland
  arbitrarily pegged out for a student project
• Different levels of organisation have different
  features, but what happens at one level may
  affect the others
• Within hierarchically structured environments,
  the behaviour of one level is strongly influenced
  by the behaviour of the two adjacent levels

15

• Environmental SYSTEMS
• versus Environmental Science/Studies?
• A difference in emphasis
• Integrated approach, emphasis on relationships
  and linkages distinguishes the systems approach

16
So whats the point of studying environmental
systems?

• Supports research with the goal of applying
  engineering principles to reduce adverse effects
  of solid, liquid, gaseous discharges on the
  land, fresh ocean waters, air that result
  from human activity impair the value of those
  resources.
• Natural systems must be understood to support
  research on innovative biological, chemical,
  physical processes used alone or as components of
  engineered systems to restore the usefulness of
  polluted land, water, air resources.

17
So whats the point of studying environmental
systems?

• Because to tackle human, environmental economic
  crises we need clear understanding of complex,
  delicate system of which we are all part
• To demonstrate reinforce the Unity of
  Science, e.g. cosmology, physics, geology,
  ecology, hydrology, biology even engineering!

18

• Environmental systems analysis is the application
  of systems analysis in the environmental field to
  describe analyse the causes, mechanisms,
  effects of, potential solution for specific
  environmental problems

The Earths systems (simplified!)
19
Systems theory

• SYSTEMS THEORY suggests that you model natural
  and human-made phenomena as a set of interrelated
  components that work together to accomplish some
  kind of process
• (Systems analysis is a quantitative
  multidisciplinary research field aimed at
  combining, interpreting communicating knowledge
  from natural social sciences, technology)
• First to find laws of complex systems
• Rapid boom - 1940s
• Treats complex systems as black box with
• inputs and outputs
• feedback processes (that counteract
  perturbations)
• CRITICISMS
• too general
• too vague it omits many of the details as to
  how a system operates

20
Or.Chaos theory?

• More mathematical, rigorous
• 1960s - Edward Lorenz
• Chaotic system sensitive to slightest change
• Amplified via positive feedback
• E.g. the weather
• Simple systems, e.g. several atoms, often have
  chaotic properties so predicting their future
  behaviour is almost impossible
• Chaos allows patterns of regularity to be
  discerned and studied

butterfly effect
21
Environmental systems theory

• Often think about systems in isolated fashion.
  However, most systems have hierarchical
  connections and structure.
• connections can be to structures that exist at
  smaller or larger scales.
• Reductionist (scientific) approach complex
  problems deconstructed
• treats each part of Earth as separate, as if it
  exists alone
• studies finer and finer detail
• Ecology HAS ALWAYS emphasised the holistic study
  of parts and the whole but was considered poor
  relation
• now realisation of the EMERGENT PROPERTY (Salt,
  1979) of an ecological unit - that which cannot
  be predicted from the study of decoupled
  components
• Environmental systems thinking provides way to
  reconcile dichotomies between analysis and
  synthesis, between reductionism and holism

22
A systems approach to the environment (or to
any natural or social science) is undeniably an
attitude of mindAND SO OF COURSEthere are
critics of what they consider to be this
philosophy of science
23
History of Earth systems thinking

• James Hutton the rock cycle
• 200 years ago
• Connection between Earth surface and interior is
  an eternal cycle of sedimentation, burial,
  deformation and plutonism, uplift and weathering
• Huttons rock cycle underlies concept of cycling
  of elements and compounds through different
  reservoirs at surface and in the interior of Earth

24
James Hutton and the Rock cycle
Rocks are weathered to sediment, then after deep
burial they undergo metamorphosis or melting or
both. Later they are deformed and uplifted to
mountains, only to be weathered again and recycled
25
Geologic cycle collective processes responsible
for the formation and destruction of Earth
materials A group of subcycles rock cycle,
tectonic cycle, hydrological cycle,
biogeochemical cycles
26
THE LAWS OF THERMODYNAMICS
Thermodynamics literally the study of heat as
it does work Energetics may be a better term
?
27
Thermodynamic (or energy) systems

• A defined system of matter, the energy content
  of that system of matter, and the exchange of
  energy between that system and its surroundings
• That part of the physical universe whose
  properties are under investigation.

28
MATTER AND ENERGY LAWS
 

• A) Law of conservation of matter
•  
• B) First law of energy (first law of
  thermodynamics)
•  
• C) Second law of energy (second law of
  thermodynamics)

29
LAW OF CONSERVATION OF MATTER

• matter is neither created nor destroyed but
  merely changed from one form to another

Changes of state involve a redistribution of
energy between the particles of matter that
compose the system or between the system and its
surroundings. Involves both transfers and
transformations of energy.
30
FIRST LAW OF THERMODYNAMICS(LAW OF CONSERVATION
OF ENERGY)  

• Applies in living systems as it does in inanimate
  ones
• Energy may be transformed from one form to
  another, but cannot be created or destroyed
• The total energy of the universe remains constant
• It is the flow or cascade of energy that helps to
  maintain the integrity of systems
• However, any conversion is less than 100
  efficient and, inevitably, some energy is lost or
  wasted, usually in the form of heat at each
  transfer and at the end, there is little energy
  left
• E.g. food chains rarely have more than 4 or 5
  links

31

• Energy cannot be re-circulated within a system
  indefinitely!
• Unless it is replenished and energy continues to
  cascade through, the system breaks down, becomes
  disordered and matter and energy change from
  concentrated forms to more dispersed forms.

32
THE SECOND LAW OF THERMODYNAMICS

• Is concerned with the direction of naturally
  occurring, or real, processes. These are
  irreversible, they proceed with an increase in
  disorder of matter and energy.
• In an isolated system, entropy tends to increase
  spontaneously

En in trope transformation
33
Entropy
Entropy is the measure of the disorder of the
system, but it can never be absolutely
quantified All physical and chemical processes
proceed towards maximum entropy. At this point
here is thermodynamic equilibrium.

• Principles were developed to apply to closed
  systems
• Open systems do not attain thermodynamic
  equilibrium of maximum entropy, but are
  maintained in a dynamic steady state by
  throughput of energy and matter

34

• Life is a battle against entropy, and without the
  constant replenishment of energy, it cannot exist

35

• Living systems and the whole biosphere are what
  Ilya Prigogine has called far-from-equilibrium
  systems that have efficient dissipative
  structures to pump out the disorder
• Living systems seemingly defy the second law of
  thermodynamics by self-organisation to maintain
  an open, far-from-equilibrium state.
• Entropy, it turns out, is not at all negative as
  the quantity of energy declines in successive
  transfers, the quality of the remainder may be
  greatly enhanced
• Prigogine won the Nobel Prize for his work on
  non-equilibrium thermodynamics

36
First two laws of thermodynamics First law
illustrated by conversion of sun energy (A) to
food (sugar, C) by photosynthesis. Second law
dictates that C is always less than A because of
heat dissipation during conversion
37
An impossible ecosystem!
Laws of thermodynamics tell us that such a
biological perpetual motion machine cannot exist
38
Maximum power principle
H.T.Odum

• Natural and human-made systems need
• continuous input of high quality energy
• storage capacity
• the means to dissipate entropy
• Systems most likely to survive efficiently
  transform the most energy into useful work for
  themselves and the surrounding systems with which
  they are linked for mutual benefit

39
Whilst on the subject
another (related fundamental) law

• The first law of ECOLOGY
• Or law of unintended consequences
• We can never do merely one thing!

40
Classification of system types

• isolated systems
• closed systems
• open systems
• morphological systems
• cascading systems - where output from one
  subsystem input to next
• process-response systems
• control systems
• ecosystems - a community of organisms in its
  abiotic environment, together with the
  relationships amongst these components

41
Open, closed and isolated systems.

• Isolated system
• one that exchanges neither matter nor energy with
  its environment
• This cannot exist naturally (with the possible
  exception being the whole universe as a system).

42
Isolated system

• A cave ecosystem may receive no light from the
  outside world, the organisms in it feeding and
  living off each other, recycling the small amount
  of energy, may be thought of as an isolated
  system, but is not truly so
• Bats may bring organic matter in from outside,
  percolating water may bring materials in solution
  or suspension or carry in small animals
• Heat enters through the surrounding rocks. Even
  thousands of metres below the surface of the
  Earth, such a system is not isolated
• Nevertheless, it can be useful to hypothesise
  about a theoretical isolated system

43
Open, closed and isolated systems.

• Closed system
• one in which energy is transferred between a
  system and its environment, but not matter.

44
Closed system

• This is fairly rare in natural systems but the
  Earth as a whole might come close to it.
• Some matter arrives in the form of meteorites,
  and there may be some small loss of material from
  the upper atmosphere, or spacecraft
• Large amounts of energy come in from the sun,
  however, and leave in the form of long-wave
  radiated heat

45
Earth is open to energy, but is essentially
closed to matter, which cycles over and through
the 4 spheres
46
Open, closed and isolated systems.

• Open system
• one that exchanges matter and energy across its
  boundary with its environment (almost all
  ecosystems are open systems)

47
Model of an ecosystem as an open, thermodynamic
non-equilibrium system. The external environment
must be considered an integral part of the
ecosystem concept.
48
Note classification of an environmental system
depends upon scale (i.e., how the systems
boundaries are defined)

• river basin system (open)
• global hydrological system (closed)

49
Equilibrium

• Many natural systems exist in a state of balance,
  known as equilibrium or homeostasis.
• Equilibrium can be defined as the average state
  of a system as measured through one of its
  attributes or elements over a specific period of
  time

50

• Static Equilibrium
• forces and reaction remain in balance, so that no
  resultant force exists, and the properties of the
  system remain constant through time

• Stable Equilibrium
• the system displays tendencies to return to the
  same equilibrium after disturbance

51

• Steady state equilibrium
• Most systems maintain this through the operation
  of positive and negative feedback mechanisms
• SYSTEM OSCILLATES AROUND STABLE AVERAGE VALUE

• Dynamic equilibrium
• Common in open systems, although there is
  continual input and output of matter and energy
  (throughflow), the state of the system remains
  constant.
• E.g. Biological populations - actual individuals
  making up that population will be forever
  changing.
• SYSTEM OSCILLATES AROUND AN AVERAGE VALUE
  TRENDING CONTINUOUSLY THROUGH TIME

52
Meta-stable equilibrium equilibriumthe system
oscillates around an average value but sudden
discontinuities knock system out of equilibrium
so that it then oscillates around a new average
value
Unstable equilibrium the system returns to a new
equilibrium after disturbance

53
Feedback

• Concept of feedback is very important in the
  understanding of dynamic equilibrium
• Feedback is the return of some output of a system
  (or subsystem) input, or where input is affected
  by present or previous output.
• i.e. some kind of 'closed loop' situation exists.
  
• Through feedback, many systems continually
  receive information from their environments,
  which helps them to adjust.
• A system capable of adjustment in this way is
  said to be self-regulating, e.g. a thermostat
• In reality the regulation of natural systems
  states involves the linking of several feedback
  mechanisms, some positive and some negative
  feedback loops

54
Feedback Response system
55
The feedback loop including predator and prey
organisms
56
Negative feedback

• Negative-feedback mechanisms control the state of
  the system by dampening or reducing the size of
  the system's elements or attributes,
  counteracting any deviation from the equilibrium
  level e.g. a thermostat
• leads to homeostasis (self-regulation)

57
Positive feedback

• Feed or increase the size of one or more of the
  system's elements or attributes over time,
  amplifying deviation from the equilibrium.
• Occasionally a change causes another change in a
  system, which possibly at several removes,
  accentuates the original change.
• In everyday life when a sequence like this occurs
  we refer to a 'vicious circle'.
• Where positive feedback is cumulative it can lead
  to increase in order and complexity (i.e. growth
  and development) or may lead to a retrogressive
  and irreversible change in state!

58
Thresholds

• State variables which, when they assume certain
  values, are capable of initiating sudden and
  sometimes dramatic changes of state
• Thresholds can be extrinsic (externally
  triggered) and intrinsic (triggered internally)
• Many thresholds exist only in extreme cases in
  all feedback processes state variables play a
  similar role in controlling operation of
  processes i.e. regulators

59
Complexity and stability

• Most natural systems are very complex
• many energy and material flow paths and numerous
  feedback links, maintaining the integrity of the
  system, and its equilibrium
• Complexity and stability are closely linked
• the more complex a system is, the more energy
  paths and feedback links there are
• A system with a multitude of links can withstand
  stress or change better than one with only a few
  components, as, if one set links or feedback
  loops is disturbed, there are others that can
  take over
• Implication for monocultures

60
Flows and Storages

• The flow of energy through a system is tightly
  connected with the flow of matter
• Butwhile energy is continuously flowing through
  systems, matter tends to circulate around them
• e.g. Photosynthesis not only fixes the sun's
  energy but also fixes C from CO2 and
  carbohydrates. While the energy fixed in
  photosynthesis and passed on to animals is
  eventually released as heat and radiated out into
  space, the C will pass through several organisms
  before reaching the atmosphere from whence it
  will be extracted by photosynthesising plants
  again. There is a circulation or cycling of C
  from one storage (stock or store) to another.

61
Flows and Storage

• Similarly, N is fixed from the atmosphere and
  passed from one storage to another (plants,
  animals, decomposing organic matter, soils,
  atmosphere) in a broadly similar way

Circulation of N in the ecosystem. Such a
circulation is known as a biogeochemical cycle
62
Summary of the elements and concepts that are
important about systems and common to all systems

• Systems have arbitrary boundaries, which we
  define at our convenience.
• Systems have inputs and outputs. No such thing as
  a closed system in reality.
• Within their boundaries, systems consists of
  components linked by some sort of function,
  transfer, or interaction (but within the
  definition of the system, the currency is
  uniform).
• Systems are nested hierarchies (systems within
  systems within systems, or systems beyond systems
  beyond systems).
• Any system can be exploded into more detailed
  subsystems. Any system can be considered a
  subsystem of a larger system.