What is the environment?

Dictionary Definition of Environment

(Merriam-Webster 1974)

1. The circumstances, objects or conditions by which one is surrounded;

2. The complex of climatic, edaphic and biotic factors that act upon an organism or an ecological community and ultimately determine its form and survival;

3. The aggregate of social and cultural conditions that influence the life of an individual or community;

4. An artistic or theatrical work that involves or encompases the spectator.

Environment as circular causal nexus

(von Uexkull 1926)

The entire function circle formed from inner world and surrounding world constitutes a whole.

Everything is ...and lawfully

lawfully produced produces something

by something else.

"Every object (H) defines two environments: an input environment and its associated causal nexus (H’), and an output environment and its associated causal nexus (H’’). The prerogative of environment definition is that of the object" (Patten 1988).

What is a system? (White, Mottershead and Harrison1992)

a set of elements with a set of properties

1. All systems have structure or organization

2. All function in some way

3. There are functional and structural relationships between parts

4. Function implies that flows and transfers occurr

5. Function requires a driving force or energy source

6. All systems have some degree of integration

Systems possess boundaries, surroundings, elements, states

The state of the system is defined when each of its properties has a definite value.

Systems can be isolated,closed or open.

In any closed system, the final state is determined by the initial condition.

In open systems the final state may be acheived with different initial conditions and in different ways.

Because systems contain elements systems are decomposable.

Systems may be open or closed.

II. Feedback. Systems

Positive Feedback is where and increase in the output of a system leads to a further increase in output .

Negative feedback occurs where the output of a system tends to reduce further output. This is a homeostatic system.

III. Uniformitarianism (Hutton 1785). The principle of uniformitarianism states that biological and physical processes active today were active in the past, although the rates of

change do not always stay constant.

IV. Changes and equilibrium in systems.

Steady state is a term that describes a system in equilibrium, with inputs balancing outputs.

Can you think of an equilibrium system?

Average residence time is the mean time for an amount of substance to pass through a storage or system.

V. The Earth as a system

The earth can be viewed as one large system.

Matter and Energy Laws: A Primer

I. One important thing about systems and living things: Life obeys physical laws.

Matter comes in a variety of forms. The atom is the simplest unit of an element that has all of the properties of that element. There are 92 naturally occurring elements in nature. Elements can combine to form compounds.

II. Energy is defined as the ability to do work. Work is the product of force and distance. Matter and energy are governed by scientific laws.

III. There are three physical laws governing matter and energy that are important to us.

A) Law of conservation of matter

B) First law of energy (first law of thermodynamics)

C) Second law of energy (second law of thermodynamics)

A. Law of Conservation of Matter: matter is neither created nor destroyed but merely changed from one form to another.

B. The First Law of Energy (First Law of thermodynamics): Energy is not created or destroyed.

Forms of energy

1) Kinetic energy is the energy that matter has because of its motion and mass.

2) Potential energy: The energy stored by an obect.

C. Second Law of Energy (Second law of thermodynamics): Entropy

Though energy is not destroyed, the quality of the energy can change. For example 90% of the energy released from gasoline in a car is wasted.

When electrical energy oscillates through the filament wires in an ordinary light bulb, it is converted into a mixture of about 5% useful radiant energy (light) and 95%

low-quality heat.

We can recycle matter but we can never recycle high-quality energy.

Can you thinl of some examples of entropy?

Organisms are tiny regions of order maintained by creating disorder around themselves.

In considering the system and its environment there is always a net increase in disorder with any spontaneous chemical or physical change.

Scientists frequently use the concept of entropy, a measure of relative randomness or disorder. A random system has high entropy (high disorder), and an orderly

system has low entropy (low disorder).

E. These laws and environmental concerns

The three laws provide us much of the information required to understand environmental questions.

Our economy depends on using greater portions of the earth's resources at increasing rates.