Environment- The Science behind the Stories

Wittgott & Laposata

1. Environmental
Systems
CHAPTER 2
GEOG 1000

2. I. Central Case Study
VANISHING OYSTERS OF THE CHESAPEAKE BAY
This Photoby Unknown Author is licensed under CC BY-SA-NC

3. Central Case Study:
Vanishing Oysters of
the Chesapeake Bay
Chesapeake Bay was the world’s
largest oyster fishery
Overharvesting, pollution, and
habitat destruction ruined it
The economy lost $4 billion from
1980 to 2010
Strict pollution standards and oyster
restoration efforts give reason for
hope

4. The Earth’s Systems
▪Understanding human impacts on the environment
requires understanding complex environment systems
▪System: a network of relationships among components
that interact with and influence one another
–Exchange of energy, matter, or information
–Receives inputs of energy, matter, or information;
processes these inputs; and produces outputs
•Feedback loop: a circular process in which a system’s
output serves as input to that same system

5. Negative feedback loop
▪Negative feedback loop: output resulting from a system moving
in one direction acts as an input that moves the system in the
other direction
•Input and output neutralize one another
•Stabilizes the system
▪Example: if we get hot, we sweat and cool down
▪Most systems in nature involve negative feedback loops

6. Positive feedback loop
Positive feedback loop: instead of stabilizing a system,
it drives it further toward an extreme
Example: white glaciers reflect sunlight and keep
surfaces cool
◦Melting ice exposes dark soil, which absorbs sunlight
◦Causes further warming and melting of more ice
Runaway cycles of positive feedback are rare in nature
◦But are common in natural systems altered by
humans

8. Environmental systems interact
▪Natural systems are divided into structural spheres
•Lithosphere: rock and sediment
•Atmosphere: the air surrounding the planet
•Hydrosphere: all water on Earth
•Biosphere: the planet’s living organisms
Plus the abiotic (nonliving) parts they interact with
▪Categorizing systems allows humans to understand Earth’s
complexity
•Most systems overlap

9. The Chesapeake Bay: a
systems perspective
The Chesapeake Bay and rivers that empty
into it are an interacting system:
–It receives very high levels of nitrogen and
phosphorus from agriculture from 6 states,
and air pollution from 15 states

10. Sources of nitrogen and phosphorus entering the
Chesapeake Bay

11. Eutrophication in the Chesapeake Bay
▪Nitrogen and phosphorus enter the Chesapeake watershed
(the land area that drains water into a river), causing….
▪Phytoplankton (microscopic algae and bacteria) to grow,
then…
▪Bacteria eat dead phytoplankton and wastes and deplete
oxygen, causing…
▪Fish and other aquatic organisms to flee or suffocate
▪Eutrophication: the process of nutrient over-enrichment,
blooms of algae, increased production of organic matter,
and ecosystem degradation

12. Eutrophication in aquatic systems

13. Global hypoxic
dead zones
Nutrient pollution from farms, cities,
and industries has led to more than 400
hypoxic (oxygen-depleted) dead zones

14. II. Matter, Chemistry, & The Environment

15. People are changing the chemistry of
Earth’s systems
Chemistry is crucial for understanding how:
▪Chemicals affect the health of wildlife and people
▪Pollutants cause acid precipitation
▪Synthetic chemicals thin the ozone layer
▪How gases contribute to global climate change

16. Matter
▪Matter: all material in the universe that has mass and
occupies space
▪Law of concertation of matter: matter can be
transformed from one type of substance into others.
-But cannot be destroyed or created.
▪Because the amount of matter stays constant
-It is recycled in nutrient cycles and ecosystems
-We cannot simply wish pollution and waste away

17. Elements
▪Element: a fundamental type of matter
-A chemical substance with a given set of properties
-Examples: nitrogen, phosphorus, oxygen
-92 Natural and 20 artificially created elements exist
▪Nutrients: elements needed in large amounts by
organism
-Examples: carbon, nitrogen, calcium

18. Atoms
▪Atoms: the smallest components that maintain an
element’s chemical’s properties
▪The atom’s nucleus(centre) has protons(positively
charged particles) and neutrons(lacking electric
charges)
-Atomicnumber: the number of protons
▪Electrons: negatively charged particles surrounding
the nucleus
-Balances the protons’ positive charge

19. Structure of an atom

20. Isotopes and
Ions
▪Isotopes: atoms of an
element with different
numbers of neutrons
▪Mass number: the
number of protons +
neutrons
▪Isotopes of an element
behave slightly differently
▪Ions: atoms that gain or
lose electrons
They are electrically
charged

21. Some isotopes are radioactive and decay
Radioactive isotopes shed subatomic particles and emit high-
energy radiation
▪They decay until they become nonradioactive stable
isotopes.
Half-life: the amount of time it takes for one-half of the atoms in a
radioisotope to give off radiation and decay.
▪Different radioisotopes have different half-lives ranging from
fractions of a second to billions of years.
▪Uranium-235, used in commercial nuclear power, has a half-
life of 700 million years.

22. Molecules and compounds
-An attraction for each other’s electrons bonds atoms
-Molecules: combination of two or more atoms
-Chemical formula: indicates the type and number of
atoms in the molecule (oxygen gas: �
2)
-Compound: a molecule composed of atoms of two or
more different elements
▪Water: two hydrogen atoms bonded to one oxygen atoms
??????
2�
▪Carbon dioxide: One carbon atom with two oxygen
atoms: ??????�
2

23. Atoms are held together with bonds
-Iconic bonds: ions of different charges bind together
▪Table Salt (NaCl): �??????
+
ion is bound with the ????????????
−
ion
-Covalent bond: atoms without electrical charges “share” electrons
▪Example hydrogen atoms share electrons -??????
2
-Solutions: electrons, molecules and compounds come together with no
chemical bonding.
▪Air contains �
2,�
2,??????
2O, ??????�
2, methane (????????????
4),????????????��??????�
3
▪Human blood, ocean water, plant sap, metal alloys

24. Hydrogen ions
determine acidity
-Water can split into ??????
+
(hydrogen Ion) and
�??????
−
(Hydroxide Ions)
-The pH scale quantifies the acidity or basicity of
solutions
-Acidicsolutions: pH <7
Contain more ??????
+
-Basicsolutions: pH > 7
Contains more &#3627408450;??????
−
-Neutralsolutions: pH: 7
-A pH of 6 contains 10 times as many ??????
+
as a pH of
7

25. Matter is composed of compounds
-Living things depend on organic compounds
-Organic compounds: carbon atoms bonded together
•The may include other elements: nitrogen, oxygen,
sulfur, and phosphorus
-Carbon can be linked in elaborate chains, rings, other
structures
•Forming millions of different organic compounds
-Inorganic compounds: lack the carbon-carbon bond

26. Hydrocarbons
-Hydrocarbons: organic compounds that contain only
carbon and hydrocarbon
•The simplest hydrocarbon is methane (natural gas)
-Fossil fuels consists of hydrocarbons
•Crude oil contains hundreds of types of hydrocarbons.

27. Macromolecules are building blocks of
life
-Polymers: long chains of repeated organic compounds
•Play key roles in building blocks of life/ the life of a cell
-Three essential types of polymers:
-Proteins
-Nucleic acids
-Carbohydrates
-Lipids are not polymers, but are also essential
•Fats, oils, phospholipids, waxes, steroids
-Macromolecules: large-sized molecules essentials to life

28. Proteins are long chains of amino acids
-Protein comprise most of an organism’s matter
-The produce tissues, provide structural support, store
energy, transport materials
-Animals use proteins to generate skin, hair , muscles, and
tendons
-Some are components of the immune system or hormones
(chemical messengers)
-They can serve as enzymes: molecules that promote
(catalyze) chemical reactions.

29. Nucleic acids
direct protein
production
-Deoxribonucleicacid(DNA)
and ribonucleicacid(RNA)
carry hereditary information
or organism.
-Nucleic acids: Long chains of
nucleiotidesthat contain
sugar phosphate and
nitrogen base.
-Genes: regions of DNA that
code for proteins that
perform certain functions.

30. Carbohydrates and lipids
-Carbohydrates: include simple sugars and large molecules of
simple sugars bonded together
-Glucose fuels cells and builds complex carbohydrates
-Plants store energy in starch, a complex carbohydrate
•Animals eat plants to get starch
-Organisms build structures from complex carbohydrates
•Chitin forms shells of insects and crustaceans
•Cellulose found in cell walls of plants
-Lipidsdo not dissolve in water
-Fats and oils (energy), waxes (structure), steroids

31. Carbohydrates and lipids
-Carbohydrates: include simple sugars and large molecules of
simple sugars bonded together
-Glucose fuels cells and builds complex carbohydrates
-Plants store energy in starch, a complex carbohydrate
•Animals eat plants to get starch
-Organisms build structures from complex carbohydrates
•Chitin forms shells of insects and crustaceans
•Cellulose found in cell walls of plants
-Lipidsdo not dissolve in water
-Fats and oils (energy), waxes (structure), steroids

32. Cells compartmentalize macromolecules
-All living things are composed of cells: the most basic unit of
organismal organization
-Cells vary in size, shape, and function
•They are classified according to their structure
-Eukaryotes: plants, animals, fungi, protists
•Contain a membrane-enclosed nucleus
•Their membrane-enclosed organallesdo specific things
-Prokaryotes: bacteria and archacea
•Single-celled. Lacking membrane-enclosed nucleus and
organelles

33. III. Energy
This Photoby Unknown Author is licensed under CC BY-NC

34. Energy fundamentals
-Energy: an intangible phenomenon that can change the position,
physical composition, temperature of matter
•Involved in biological, chemical, physical processes
-Potential energy: energy of position
-Kinetic energy: energy of motion
-Chemical energy: potential energy held in the bonds between
atoms
-Changing potential into kinetic energy
-energy
-Produces motion, action, or heat

35. Potential vs. kinetic energy
Potential energy stored in our food becomes kineticenergywhen
we exercise and releases carbon dioxide, water, and heat as by-
products.

36. Energy is conserved but changes in
quality
-First law of thermodynamics: energy can change form
but cannot be created or destroyed.
-Second law of thermodynamics: energy changes from
a more-ordered to a less-ordered state
•Entropy: an increasing state of disorder
-Living organism resist entropy by getting energy from
food and photosynthesis.
•Dead organisms get no energy and through
decomposition lose their organized structure.

37. The sun’s energy powers living systems
-Energy that powers Earth’s ecological systems comes
mainly from the sun.
-The sun releases radiation from the electromagnetic
spectrum
•Only some is visible light

38. Using solar radiation to produce food
-Autotrophs (producers):
organisms that use the sun’s
energy to produce their own
food
•Plants, algae, cynobacteria
-Photosynthesis: the process of
turning the sun’s light energy
into high-quality chemical
energy
•Sunlight converts carbon
dioxide and water into
sugars

39. Photosynthesis produces food
-Chloroplasts: organelles where photosynthesis occurs
•Contain chlorophyll: a light-absorbing pigment
•Lightreaction: solar energy splits water and creates high-
energy molecules that fuel that growth and maintenance
•Calvincycle: links carbon atoms from carbon dioxide into
sugar (glucose)

40. Cellular respiration releases energy
-It occurs in all living things (plants, animals, etc.)
-Organisms use chemical energy created by photosynthesis
•Oxygen breaks the high-energy chemical glucose bonds
•The energy is used to make other chemical bonds or tasks
-Heterotrophs: organisms that gain energy by feeding on others
◦Animals, fungi, microbes
◦The energy is used for cellular tasks

41. IV. Ecosystems

42. Ecosystems
-Ecosystem: all organisms and nonliving entities occurring and
interacting in a particular area
•Animals, plants, water, soil, nutrients, etc.
-Biological entities are tightly intertwined with the chemical and
physical aspects of their environment
-For example, in the Chesapeake Bay estuary(a water body
where fresh river water flows into salt ocean water):
•Organisms are affected by water, sediment, and nutrients
from the water and land
•The chemical composition of the water is affected by
organism photosynthesis, respiration, and decomposition

43. Energy and matter flow through ecosystems
Sun energy flows in one direction
through ecosystems
–Energy is processed and transformed
Matter is recycled within ecosystems
–Outputs: heat, water flow, and
waste

44. Energy is converted to biomass
Primary production:conversion ofsolar energy to chemical energy in
sugars by autotrophs during photosynthesis
Gross primary production: total amount of chemical energy produced by
autotrophs
◦Most energy is used to power their own metabolism
Net primary production: energy remaining after respiration
▪Equals gross primary production –cellular respiration
▪It is used to generate biomass (leaves, stems, roots)
▪Available for heterotrophs

45. Primary
productivity of
ecosystems
•Productivity: rate at
which autotrophs
convert energy to
biomass
•High net primary
productivity:
ecosystems whose
plants rapidly convert
solar energy to
biomass
(photosynthesis)

46. A global map of net primary productivity
NPP increases with temperature and precipitation on land, and with
light and nutrients in aquatic ecosystems

47. Ecosystems interact across landscapes
Ecosystems vary greatly in size (puddle, forest, bay, etc.)
The term ecosystemis most often applied to self-contained systems of
moderate geographic extent
◦Adjacent ecosystems may interact extensively
◦Ecotones: transitional zones between two ecosystems in which elements of
each ecosystem mix
It may help to view ecosystems on a larger geographic scale
◦Encompassing multiple ecosystems
◦Geographic information systems (GIS)use computer software to layer
multiple types of data together

48. Landscape ecology
Landscape ecology: the study of how landscape structure
affects the abundance, distribution, and interaction of
organisms
◦Useful for studying migrating birds, fish, mammals
◦Helpful for planning sustainable regional development
Patches: ecosystems, communities or habitat form
the landscape and are distributed in complex
patterns (a mosaic)
This landscape consists of
a mosaic of patches of 5
ecosystems

49. Conservation biology
Conservation biologists: study the loss, protection, and restoration of
biodiversity
◦Humans are dividing habitat into small, isolated patches
◦Corridors of habitat can link patches
Populations of organisms have specific habitat requirements
◦They occupy suitable patches of habitat in the landscape
If a habitat is highly fragmented and isolated
◦Organisms in patches may perish
Conservation biologists may use corridors of habitat to link patches to
preserve biodiversity

50. Modeling helps us understand ecosystems
Model: a simplified representation of a complicated natural process
◦Helps us understand processes and make predictions
Ecological modeling: constructs and tests models to explain and predict
how ecological systems work
◦Grounded in actual data and based on hypotheses
◦Extremely useful in large, intricate systems that are hard to isolate and study
◦Example: studying the flow of nutrients into the Chesapeake Bay and oyster
responses to changing water conditions

51. Ecosystems provide vital services
All life on Earth (including humans) depends on healthy,
functioning ecosystems
Ecosystem services: essential services provided by healthy,
normally functioning ecosystems
◦When human activities damage ecosystems, we must devote
resources to supply these services ourselves
◦Example: if we kill off insect predators, farmers must use
synthetic pesticides that harm people and wildlife
One of the most important ecosystem services:
◦Nutrients cycle through the environment in intricate ways

52. Ecological processes
provide services

53. Nutrients circulate through ecosystems
-Nutrients move through the environments in complex ways
▪Matter is continually circulated in an ecosystem
-Nutrient (biogeochemical) cycle: the movement of nutrients
through ecosystems
-Pool (reservoir): a location where nutrients remain for varying
amounts of time (residence time)
-Source: a reservoir releases more materials than it accepts
-Sink: a reservoir that accepts more than it releases
-Flux: the rate at which materials move between reservoirs
▪Can change over time

54. Humans affect nutrient cycling
-Human activities affect nutrient cycling
▪Altering fluxes, residence times, and amounts of nutrients in
reservoirs
reservoir reservoir

55. The water cycle affects all other cycles
-Water is essential for biochemical reactions and is involved in
nearly every environmental systems and cycle
-Hydrologiccycle: the flow of liquid, gaseous, and solid water
through the environment
▪Less than 1% is available as fresh water
-Evaporation: conversion of liquid to gaseous water
-Transpiration: release of water vapor by plants
-Precipitation: rain or snow returns water to earth’s surface
-Runoff: water flows into streams, lakes, rivers, oceans

56. Water is also stored underground
-Infiltration: water soaks down through rock and soil to recharge
aquifers
-Aquifers: underground reservoirs of spongelike regions of rock
and soil that hold water
-Watertable: the uppermost level of groundwater held in in an
aquifers
-Water in aquifers may be ancient (thousands of years old)

57. The hydrologiccycle

58. Human impacts on hydrologiccycle
-Humans have affected almost every flux, reservoir, and
residence time in the water cycle
-Damming rivers slows water movement and increases
evaporation
-Removal of vegetation increases runoff and erosion while
decreasing
-Overdrawing surface and groundwater for agriculture, industry,
and domestic uses lowers water tables.
-Emitting air pollutants that dissolve in water changes the nature
of precipitation and decreases cleansing.

59. The carboncycle
-Carbon cycle: describes carbon’s route in the environment
•Carbon forms essential biological molecules
-Through photosynthesis, producers move carbon from the air
and water to organisms
•Respiration returns carbon to the air and water
-Oceans are the second largest reservoir of carbon
-Decomposition returns carbon to the sediment, the largest
reservoir of carbon
•Ultimately, it may be converted into fossil fuels

60. The carboncycle

61. Humans affect the carboncycle
-Burning fossil fuels moves carbon from the ground to the air
•Since mid-1700s, people have added over 275 billion tons of
carbon dioxide to the atmosphere
-Cutting forests and burning fields moves carbon from organisms
to the air
•Less carbon dioxide is removed by photosynthesis
-Today’s atmospheric carbon dioxide reservoir is the largest in
the past 800,000 years
•The driving force behind climate change

62. Nitrogencycle involves bacteria
-Nitrogen makes up 78% of the atmosphere
-It is contained in proteins, DNA and RNA
•It is also essential for plant growth
-Nitrogencycle: describes the routes of nitrogen through the
environment
•Nitrogen gas is inert and cannot be used by organism
-It needs lightning, bacteria, or human intervention to become
biologically active and available to organisms
•Then it is a potent fertilizer

63. Nitrogenmust become biologically
available
-Nitrogen fixation: nitrogen-fixing soil bacteria or lightning
“fixes” nitrogen gas into ammonium
•Nitrogen-fixing bacteria live in legumes (e.g. soybeans)
-Nitrification: bacteria convert ammonium ions first into nitrite
ions then into nitrate ions
•Plants can take up these ions
-Nitrite and nitrate also come from the air or fertilizers
-Animals obtain nitrogen by eating plants or other animals
-Denitrifyingbacteria: convert nitrates in soil or water or
gaseous nitrogen, releasing it back into the atmosphere

64. The nitrogencycle

65. Humans greatly affect the Nitrogencycle
-Historically, nitrogen fixation was a bottleneck: limited the flux
of nitrogen from air into water-soluble forms
-Industrial fixation fixes nitrogen on a massive scale
•Overwhelming nature’s denitrification abilities
-Excess nitrogen leads to hypoxia in coastal areas
-Nitrogen-based fertilizers strip the soil of other nutrients
•Reducing fertility
-Burning forests and fossil fuels leads to acid precipitation, adds
greenhouse gases, and creates photochemical smog

66. The phosphoruscycle

67. Humans affect the phosphoruscycle
-Fertilizer from lawns and farmlands
•Increases phosphorus in soil
•Its runoff into water increases phytoplankton blooms and
hypoxia
-Wastewater containing detergents releases phosphorus to
waterways

68. Controlling nutrient pollution in
waterways
-Reduce fertilizer use in farms and lawns
-Change timing of fertilizer applications to minimize runoff
-Manage livestock manure applications to farmland
-Plant vegetation “buffers” around streams to trap runoff
-Restore wetlands and create artificial ones to filter runoff
-Improve sewage-treatment technologies
-Restore frequently flooded lands
-Reduce fossil fuel combustion

69. Conclusion
-Life interacts with its abiotic environment in ecosystems
through which energy flows and materials are recycled
-Understanding biogeochemical cycles is crucial
•Humans are changing the ways those cyclesfunction
-Understanding energy, energy flow, and chemistry
increases our understanding of organisms
•How environmental systems function
-Thinking in terms of systems can teach us how to:
•Avoid disrupting earth’s processes and to mitigate any
disruption we cause