F. Herbert Bormann, Gene Likens, et al.: Hubbard Brook
Experimental Forest in NH (U.S.) Compared the loss of water and
nutrients from an uncut forest (control site) with one that had
been stripped (experimental site) Deforested area: 30-40% increase
in water flowing out of forest, eroded soil, and lost 6 to 8 times
more nutrients
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Concept 2-1 Scientists collect data and develop theories,
models, and laws about how nature works. Science endeavor to
discover how nature works and to use that knowledge to make
predictions about what is likely to happen in nature. Based on the
assumption that events in the natural world follow orderly
cause-and-effect patterns that can be understood through careful
observation, measurements, experimentation, and modeling.
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Figure 2.2 What scientists do. The essence of science is this
process for testing ideas about how nature works. Scientists do not
necessarily follow the exact order of steps shown here. For
example, sometimes a scientist might start by formulating a
hypothesis to answer the initial question and then run experiments
to test the hypothesis.
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Some terms Data information needed to answer a question;
collected with senses or extensions of the senses. Experiments
procedures carried out under controlled conditions to gather
information and test ideas. Scientific hypothesis a possible and
testable explanation of what is observed in nature or in the
results of their experiments. Model an approximate representation
or simulation of a system being studied. Scientific theory
well-tested hypothesis or group of hypotheses; and explanation that
has broad predictive power. Peer review
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Important features of the scientific process Curiosity
Skepticism Peer review Reproducibility Openness to new ideas
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Some revisions in a popular environmental story Polynesians
arrived about 800 years ago Population may have reached 3000 Used
trees in an unsustainable manner, but rats may have multiplied and
eaten the seeds of the trees See p. S31 for other civilizations
that collapsed because of unsustainable use of resources.
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Important scientific tools Inductive reasoning uses specific
observations and measurements to arrive at a general conclusion or
hypothesis. Deductive reasoning uses logic to arrive at a specific
conclusion based on a generalization or premise. Scientists also
use Intuition Imagination Creativity
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Scientific theory and explanation for natural phenomena. Widely
tested Supported by extensive evidence Accepted by most scientists
in a particular area Scientific law, or law of nature a well-tested
and widely accepted description of what we find happening over and
over again in the same way in nature. Paradigm shift when new
discoveries and new ideas overthrow a well-accepted theory; occurs
when majority of scientist in the related fields a new
paradigm.
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Greenhouse effect, one of the most widely accepted theories in
atmospheric science. Since 1980, many climatologist have been
focused on these questions: How much has the earths atmosphere
warmed during the last 50 years? How much of this warming is due to
human activity? How much is the atmosphere likely to warm in the
future and will this affect climate? The UN and the World
Meteorological Organization established the IPCC Studies how
climate systems work, document past climate changes, and project
future changes.
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The 4 th IPCC report, 2007 Very likely (90-99% probability)
that the troposphere is getting warmer. Very likely (90-99%
probability) that human activities have been the cause. Very likely
(90-99% probability) that temperatures will increase by at least 3
o C between 2005 and 2100. Report is considered reliable science.
Some individual scientist disagree. Media coverage causes bias by
providing balanced coverage.
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Tentative science, or frontier science preliminary results that
have not been widely tested and accepted by peer review. Reliable
science consists of data, hypotheses, theories and laws that are
widely accepted by scientists who are considered experts in the
field; based on a self-correcting process. Unreliable science
hypotheses and results that are presented as reliable without
having undergone the rigors of peer review, or that have been
discarded as a result of peer review. Questions to ask to help
evaluate scientific claims, p. 34
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Particular hypotheses, theories, or laws have a high
probability of being true while not being absolute. Cant prove
anything; there is always some degree of uncertainty in
measurements, observations and models. Bias can be minimized by
scientists. Statistical methods may be used to estimate very large
or very small numbers. Just because they are estimates, the numbers
should not be dismissed. The estimates can indicate important
trends. Environmental phenomena involve interacting variables and
complex interactions. Scientific process is limited to the natural
world.
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Statistics mathematical tools used to collect, organize, and
interpret numerical data. Probability - the chance that something
will happen or be valid. Critical Thinking: What does it mean when
an international body of the worlds climate experts says that there
is a 90-99% chance (probability of 0.90-0.99) that human
activities, led by emissions of carbon dioxide from burning fossil
fuels, have been the main cause of the observed atmospheric warming
during the past 50 years? Why would the probability never be
100%?
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Concept 2-2 Matter consists of elements and compounds, which
are in turn made up of atoms, ions, or molecules.
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Matter Has mass and takes up space The stuff that makes up life
and its environments Elements Unique properties Cannot be broken
down chemically into other substances Four elements O, C, H, and N
make up about 96% of the mass of most organisms. Compounds Two or
more different elements bonded together in fixed proportions
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Atom basic building block of matter; smallest unit of matter
into which an element can be divided and still retain its chemical
properties. Atomic theory Subatomic particles Protons (p) with
positive charge and neutrons (0) with no charge in nucleus
Negatively charged electrons (e) orbit the nucleus Mass number
Protons plus neutrons Isotopes
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Ions Gain or lose electrons Form ionic compounds pH Measure of
acidity H+ and OH-
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Molecule Two or more atoms of the same or different elements
held together by chemical bonds Chemical formula
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Inorganic compounds Organic compounds Hydrocarbons and
chlorinated hydrocarbons Simple carbohydrates Macromolecules:
complex organic molecules; polymers made of subunit monomers.
Complex carbohydrates (simple sugars) Proteins (amino acids)
Nucleic acids (nucleotides) Lipids (fats, oils and waxes)
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The bridge between living and nonliving lies somewhere between
macromolecules and cells. Cells fundamental units of life Genes
sequences of nucleotides within the DNA Chromosomes composed of
many genes
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Solid Liquid Gas
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Matter quality measure of how useful a form of matter is to
humans as a resource based on availability and concentration.
High-quality matter Low-quality matter Figure 2.6 Examples of
differences in matter quality. High- quality matter (left column)
is fairly easy to extract and is highly concentrated; low-quality
matter (right column) is not highly concentrated and is more
difficult to extract than high-quality matter.
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Concept 2-3 When matter undergoes a physical or chemical
change, no atoms are created or destroyed (the law of conservation
of matter).
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Physical change chemical composition does not change. Chemical
change, chemical reaction Nuclear change Natural radioactive decay
Radioisotopes: unstable Nuclear fission Chain reaction when
multiple fissions of a certain mass occurs; releases enormous
amounts of energy. Nuclear fusion
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Figure 2-7 a
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Figure 2-7 b
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Figure 2-7 c
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Modeling Radioactive Decay
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Law of conservation of matter What is meant by matter
consumption? Matter is converted from one form to another. There is
no away as in to throw away.
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Concept 2-4A When energy is converted from one form to another
in a physical or chemical change, no energy is created or destroyed
(first law of thermodynamics). Concept 2-4B Whenever energy is
changed from one form to another, we end up with lower- quality or
less usable energy than we started with (second law of
thermodynamics).
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What is energy? Work = force x distance Kinetic energy Heat
(textbook defines incorrectly.) Transferred by radiation,
conduction, or convection Electromagnetic radiation Potential
energy Stored energy Can be changed into kinetic energy
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Energy quality a measure of an energy sources capacity to do
useful work. High-quality energy concentrated w/ high capacity to
do work. Examples: fossil fuels, high heat, strong wind, nuclear
fission. Low-quality energy dispersed and little capacity to do
work. Examples: thermal energy in atmosphere and oceans.
Slide 41
Thermodynamics is the study of energy transformations. First
Law of Thermodynamics Energy input always equals energy output
Slide 42
Second Law of Thermodynamics Energy always goes from a more
useful to a less useful form when it changes from one form to
another. Energy quality is lost. Examples: 94% of energy in gas is
degraded to heat, only 6% gets you to places. Only 5% of electrical
energy generates light in an incandescent bulb. Heat bulb? Energy
efficiency, or energy productivity This is a measure of how much
useful work is done by a particular input of energy into a system.
16% of energy in the US actually does useful work. 41% is
unavoidable. 43% is unnecessarily wasted. Lesson: Cheapest and
quickest way to get more energy is to stop wasting almost half the
energy we use.
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Concept 2-5A Systems have inputs, flows, and outputs of matter
and energy, and their behavior can be affected by feedback. Concept
2-5B Life, human systems, and the earths life support systems must
conform to the law of conservation of matter and the two laws of
thermodynamics.
Slide 45
System a set of components that function and interact in some
regular way. Most systems have the following key components: Inputs
from the environment Flows, or throughputs Outputs to the
environment
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Feedback any process that increases (positive feedback) or
decreases (negative feedback) a change to a systems. 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 the system.
Positive feedback loop Negative, or corrective, feedback loop
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Complex system often have time delays between the input of a
feedback stimulus and the response to it. Time delays vary
depending on the sytem. Time delays can allow and environmental
problem to build up to a tipping point, or threshold level. Causes
a shift in the behavior of a system Examples: clearing vegetation,
population growth, leaks from toxic waste dumps, global climate
change, degradation of forests from long-term exposure to
pollutants.
Slide 51
Synergistic interaction, or synergy occurs when two or more
processes interact so that the combined effect is greater than the
sum of their separate effects. Helpful Harmful E.g., Smoking and
inhaling asbestos particles
Slide 52
Deforested areas turning to desert Coral reefs dying Glaciers
melting Sea levels rising