Topic 1: Systems SYSTEM: an assemblage of parts and their - - PDF document

Mr G’s Environmental Science

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Environmental Systems

• SYSTEM: an assemblage of parts and their relationship forming a

functioning entirety or whole.

Topic 1: Systems

• 1970’s James Lovelock proposes the GAIA

hypothesis

• The planet acts like a single biological

being made up of individual and interconnected units

• A SYSTEM

Topic 1: Systems

Physical Climate System Biogeochemical System

Atmospheric Physics/Dynamics Tropospheric chemistry

Soil

Marine Biogeochemistry Terrestrial Ecosystems

Ocean Dynamics Terrestrial energy/moisture

Human Activities Strotspheric Chemistry/ Dynamics

External Forcing Global Moisture

Volcanoes

Polluntants Climate Change

CO2 CO2 Land Use Sun

1 2 3 4

• Systems involve:
• Inputs
• Outputs
• Processes

Topic 1: Systems

Inputs of Water, Carbon Dioxide and Sunlight Light energy is trapped by the chlorophyll inside the chloroplasts Energy is released, splitting water into hydrogen and

• xygen

Oxygen is realesed to the atmosphere The hydrogen combines with carbon dioxide to make glucose

• Individual systems can be sub-units of bigger systems

Topic 1: Systems

• xygen

• A food chain includes photosynthesising plants
• All systems include inputs, processes and outputs

Topic 1: Systems

Input Output Process Input Output Process Input Output Process

• Open Systems
• Closed Systems
• Isolated Systems

Topic 1: Systems

1.1.2: Types of System

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Open Systems

Topic 1: Systems

1.1.2: Types of System

• exchange matter and energy with its surroundings.

Closed Systems

Topic 1: Systems

1.1.2: Types of System

• exchange energy but not matter.

Light Energy From the Sun Long wave energy (heat) returned to space

Closed Systems

Topic 1: Systems

1.1.2: Types of System

• Biosphere 2

Isolated Systems

Topic 1: Systems

1.1.2: Types of System

• An isolated system exchanges

neither matter nor energy.

• Isolated systems do not

exist naturally

• Possible to think of the

entire Universe as an isolated system

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Energy in all systems is subject to the Laws of Thermodynamics

Topic 1: Systems

1.1.3: Energy in Systems The First Law:

Topic 1: Systems

1.1.3: Energy in Systems

• Energy is neither created

nor destroyed..

• Energy can only change

from one form to another

• Often called: The Law
• f

Conservation

• f

energy

Incoming solar radiation (light energy) is trapped by plants and converted to sugars (stored chemical energy) Consumers (herbivores) eat the plants (producers) and the stored chemical energy gets passed up the food chain Consumers (carnivores) eat other consumers (herbivores) and the stored chemical energy gets passed up the food chain again No energy has been created or destroyed in the food chain it has only moved or changed form

The First Law:

Topic 1: Systems

1.1.3: Energy in Systems

• Energy is neither created

nor destroyed..

• Of the sunlight falling on

Earth not all of it is used for photosynthesis.

The Second Law:

Topic 1: Systems

1.1.3: Energy in Systems

• The entropy of an isolated

system not in equilibrium will tend to increase over time

• Energy conversions are

never efficient and the more conversions in a system the greater the total inefficiency Heat generated during work e.g. respiration Heat generated during work e.g. respiration Heat generated during work e.g. respiration

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The Second Law:

Topic 1: Systems

1.1.3: Energy in Systems

• Can be thought of as a

simple word equation

• Energy = Work + Heat (and
• ther waste products)
• Or the spreading out of

energy

Input Energy Conversion process Heat Useful Energy Work

Open systems tend to exist in a state of balance

Topic 1: Systems

1.1.4: Equilibria

Two types of Equilibrium

Topic 1: Systems

1.1.4: Equilibria

• Static
• Dynamic

Topic 1: Systems

1.1.4: Equilibria

• Static:

Where components of the system remain constant

• ver a long period of time

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Topic 1: Systems

1.1.4: Equilibria

• “Dynamic”:

Difficult concept A system is in a steady state because the inputs and

• utputs

that affect it approximately balance

• ver a long period of time

20 40 60 80 1900 1905 1910 1915 1920 Snowshoe Hare Lynx

Year Number of pelts (1000s)

Topic 1: Systems

1.1.5: Feedback

A system are continually affected by and react to information (stimuli) The final outcome of the process is governed by feedback

• Negative
• Positive

Topic 1: Systems

1.1.5: Feedback

Negative feedback

20 40 60 80 1900 1905 1910 1915 1920 Snowshoe Hare Lynx Year

N u m b e r

• f

p e l t s ( 1 s )

• tends

to damp down, neutralize or counteract any deviation from an equilibrium, and promotes stability.

Prey population grows Prey population falls Predator population falls Predator population grows More food More hunting Less hunting Less food More food More hunting Less hunting Less food

Topic 1: Systems

1.1.5: Feedback

Positive feedback

• Amplifies
• r

increases change; it leads to exponential deviation away from an equilibrium.

Higher temperatures Land and sea temperatures rise Increased evaporation More water vapour Wetter Atmosphere More heat trapped by atmosphere

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Topic 1: Systems

1.1.6: Transfers and Transformations

Both Material and Energy move or flow through ecosystems

• A transfer is when the flow does not involve a change of

form

• A transformation is a flow involving a change of form
• Both types of flow use energy - transfers being simpler use

less

Topic 1: Systems

1.1.6: Transfers and Transformations

Both Material and Energy move or flow through ecosystems

Topic 1: Systems

1.1.6: Transfers and Transformations

Both Material and Energy move or flow through ecosystems

Topic 1: Systems

1.1.6: Transfers and Transformations

Both Material and Energy move or flow through ecosystems

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Topic 1: Systems

1.1.6: Transfers and Transformations

Both Material and Energy move or flow through ecosystems

Transfers can involve:

• The movement of material through living organisms (carnivores eating other animals)
• The movement of material in a non-living process (water being carried by a stream)
• The movement of energy (ocean currents transferring heat)

Topic 1: Systems

1.1.6: Transfers and Transformations

Both Material and Energy move or flow through ecosystems

Transformations can involve:

• Matter (glucose converted to starch in plants)
• Energy (Light converted to heat by radiating surfaces)
• Matter to energy (burning fossil fuels)

Topic 1: Systems

1.1.7: Flows and Storages

Both energy and matter flows (inputs and outputs) through ecosystems but at times is also stored (stock) within the ecosystem:

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