human biology - napa valley college 105/chapt23... · human biology sylvia s. mader ... phosphorus...

Human Biology

Sylvia S. Mader

Michael Windelspecht

Chapter 23

Global Ecology and Human

Interferences

Lecture Outline

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

See separate FlexArt PowerPoint slides

for all figures and tables pre-inserted into

PowerPoint without notes.

Points to Ponder• What is an ecosystem and what are its biotic components?

• What are the energy flow and chemical cycling in an ecosystem?

• What are the two major ecosystems on earth?

• Describe the 3 types of terrestrial ecosystems and the 2 types of aquatic ecosystems.

• Compare and contrast food webs and food pyramids.

• What is a biogeochemical cycle?

• What is a reservoir and an exchange pool.

• Explain the water, carbon, nitrogen, and phosphorus cycles.

• What human activities interfere with these cycles?

• What problems are we creating by altering these pathways?

• What is ozone depletion and why is this important?

• What are the pros and cons to drilling in the Arctic National Wildlife refuge?

The nature of ecosystems

• Biosphere – the regions of the Earth’s waters,

crust, and atmosphere inhabited by living

organisms

• Ecosystem – a place where organisms interact

between each other and their environment

– Terrestrial: several distinct types based on

temperature and waterfall

– Aquatic: freshwater and marine

23.1 The nature of ecosystems

Terrestrial ecosystems

• Forests – dominated by trees

• Tropical rain forest

• Coniferous forests (taiga)

• Temperate deciduous forests

• Grasslands – dominated by grass

• Tropical grasslands

• Temperate grasslands (prairie)

• Deserts – characterized by lack of available

moisture

• Tundra

• Deserts


taiga

temperate forest desert

tropical rain forest tropical grassland (savanna)

temperate grassland (prairie)

Terrestrial ecosystems23.1 The nature of ecosystems


tropical rain forest

temperate grassland (prairie)

desert

tropical grassland (savanna)

taiga

winter tundraautumn tundra

temperate forest

(temperate, desert, rain forest, prairie): © Corbis RF; (savanna): © Gregory Dimijan/Photo Researchers, Inc.; (taiga): © Brand X Pictures/PunchStock RF;

(autumn tundra): © Joseph Van Os/Getty Images; (winter tundra): © Oxford Scientifi c/Getty Images

Aquatic ecosystems

• Marine

• Seashores

• Oceans

• Coral reefs

• Estuaries

• Freshwater

• Lakes

• Ponds

• Rivers

• Streams


Aquatic ecosystems23.1 The nature of ecosystems

Components of an ecosystem

• Abiotic components – nonliving environment

• Biotic components - living components• Autotrophs – producers

• Heterotrophs – consumers• Herbivores – feed on plant and algae

• Carnivores – feed on other animals

• Omnivores – eat both plants and animals

• Detritus feeders – feed on decomposing organic matter

• Niche – the role an organism plays in an ecosystem such as how it gets its food, what it eats, and how it interacts with other organisms


Biotic components of an ecosystem


Energy flow and chemical cycling

• Energy flow:• Begins and continues when producers absorb solar energy

• Occurs as nutrients pass from one population to another

• This energy is converted to heat that dissipates into the environment

• Only a portion of energy is passed to organisms as they consume one another

• Chemical cycling: • Inorganic nutrients are returned to producers from the

atmosphere or soil

• Chemicals recycle within and between ecosystems


Energy flow and chemical cycling



solar

energy heat

consumers

producers

inorganic

nutrient pool

heat decomposers

heat

energy

nutrients

Fate of food energy taken

in by a herbivore



Heat to

environment

Energy to

carnivores

Energy

to detritus

feeders

growth and reproduction

© George D. Lepp/Photo Researchers, Inc.

Energy flow

• Food web – describes who eats whom• Grazing food web

• Detrital food web

• Trophic levels – composed of all organisms that feed at a particular link in the food chain

• Producers, primary consumers, and secondary consumers

• Ecological pyramid – reflects the loss of energy from one trophic level to another

• Only about 10% of the energy of one trophic level is available to the next trophic level

23.2 Energy flow

Food webs23.2 Energy flow


shrewssalamanderscarnivorous invertebrates

(beetles)

invertebrates

(earthworms)

b. Detrital food web

fungi and bacteria

(decomposers)

a. grazing food web

skunks

foxes

detritussnakes

mice

rabbitschipmunks

owls

CarnivoresHerbivores/OmnivoresAutotrophs (Producers)

fruits and

nuts

leaf-eating

insects

hawksbirds

deer

mice

detritus

detritus

leaves

An example of a food pyramid23.2 Energy flow


producers

809g/m2

herbivores

37g/m2

carnivores

11g/m2

top carnivores

1.5g/m2

Biogeochemical cycles

• Biogeochemical cycles are pathways by which chemicals circulate through an ecosystem including both living and nonliving components

1. Water cycle

2. Carbon cycle

3. Nitrogen cycle

4. Phosphorus cycle

• Reservoir – fossil fuels, minerals in rocks, and sediment in oceans that contain inorganic nutrients that are limited in availability

• Exchange pools – atmosphere, soil, and water that are ready sources of inorganic nutrients

23.3 Global Biogeochemical cycles

Biogeochemical cycles



Community

Exchange

Pool

• atmosphere

• soil

• water

Reservoir

• fossilfuels

• mineral

in rocks

• sediment

in oceans

Water cycle

• Water evaporates from the bodies of water, land, and plants and returns when water falls on land to enter the ground, surface waters, or aquifers

• Human activities that interfere:• Withdraw water from aquifers

• Clear vegetation from the land and build structures that prevent percolation and increase runoff

• Add pollutants to water such as sewage and chemicals


Water cycle



Ice

1 2

4

5

3 2

6

H2O in Atmosphere

evaporation

from ocean

precipitation

to ocean

transport of water vapor by wind

transpiration from plants

and evaporation from soilprecipitation

over land

lake

fresh water runoff

aquifer

Groundwaters

Ocean

Carbon cycle

• CO2 is exchanged between the atmosphere

and living organisms

• Plants incorporate atmospheric CO2 into

nutrients through photosynthesis that can be

used by living organisms

• CO2 is returned to the atmosphere through

respiration


Carbon cycle23.3 Global Biogeochemical cycles


7

1

7

24

3

5

6

CO2 in Atmosphere

Ocean

bicarbonate (HCO3–)

diffusion

destruction

of vegetation

Land plants

Soils

dead

organisms

and animal

waste

photosynthesis

combustion

decay

respiration

coal

oil

natural gas

Carbon cycle

• Human activities that interfere:

• Burning of fossil fuels and the destruction of forests

are depositing CO2 to the atmosphere faster than it

is being removed

• CO2 and other gases (N2O and CH4) are being

emitted due to human activities

• These gases are called greenhouse gases because

they trap heat that contributes to global warming


Greenhouse gases and global warming



solar radiation solar radiation reflectedsolar radiation

reflected

green house gases

in atmosphere

Greenhouse

effect

reradiated

clouds

absorbed

Solar radiation that

passes through

the atmosphere

warms the Earth’s

surface.

Clouds, which contain

water vapor, absorb

infrared rays (heat) from the

earth’s surface and warm

the surface by downward

reradiation of a portion of

these rays.

Green house gases, including carbon

dioxide and methane, also cause the

atmosphere to absorb and reradiate infrared

rays toward the surface of the Earth. As the

concentration of green house gases

increases, the temperature of the Earth is

expected to increase also.

Nitrogen cycle

• 78% of the atmosphere is nitrogen gas but it is

not in a usable form by plants

• Nitrogen-fixing bacteria convert nitrogen gas to

ammonium that can be used by plants

• Nitrifying bacteria convert ammonium to nitrate

• Bacteria convert nitrate back to nitrogen gas

through a process called dentrification


Fig. 23.12

Nitrogen cycle23.3 Global Biogeochemical cycles


NO3–

3

4

5

6

8

8

2

2

7

1

7

1

phytoplankton

N2 in Atmosphere

N2 fixation

nitrogen-fixing

bacteria in nodules

And soil

plants

denitrifying

bacteria

decomposers

Biotic

Community

nitrifying

bacteria

NH4+

NO2

NO2

denitrification NH4+

cyanobacteria

Biotic

Community

denitrifying bacteria

nitrification

human

activities

runoff

decomposers

dead organisms

and animal waste

denitrificationN2 fixation

Nitrogen cycle

• Human activities interfere:

• We add nitrogen fertilizers that run off into lakes and

streams that cause major fish kills by eutrophication

• Burning of fossil fuels

- puts nitrogen oxides and sulfur dioxide into the atmosphere

where they combine with water vapor to form acids that

return to earth as acid deposition

- Result in nitrogen oxides and hydrocarbons that react with

one another to produce smog


Nitrogen cycle23.3 Global Biogeochemical cycles

Phosphorus cycle

• Phosphate ions become available to living organisms by the slow weathering of rocks

• Phosphate is a limiting nutrient in ecosystems



1

4

3

5

8

6

7

8

2

8

minable rock

phosphate mining

geologic uplift

plants

animals and

animal wastes

decomposers

sewage treatment

plants

phosphate

in solution

biota

detritus

sediments

Biotic

Community phosphate

in soil

fertilizer

runoff

weathering

Phosphorus cycle

• Human activities interfere:

• Runoff of phosphate due to fertilizer and discharge

from sewage treatment plants results in

eutrophication

• Sources of pollution:

- Point source – specific sources

- Nonpoint sources – runoff from land


Sources of pollution


Biodegradable organic compounds

(e.g., sewage, wastes from food-processing

plants, paper mills, and tanneries)

Nitrates and phosphates from detergents,

fertilizers, and sewage treatment plants

Bacteria and viruses from sewage and

barnyard waste (causing, for example,

cholera, food poisoning, and hepatitis)

Acids from mines and air pollution;

dissolved salts; heavy metals

(e.g., mercury) from industry

Radioactive substances from nuclear

power plants, medical and research facilities

Sources of Water Pollution

Leading to Cultural Eutrophication

Oxygen-demanding

waste

Plant nutrients

Sediments

Thermal discharges

Enriched soil in water due to soil erosion

Heated water from power plants

Health Hazards

Disease-causing agents

Synthetic organic

compounds

Inorganic chemicals

and minerals

Radiation

Pesticides, industrial chemicals

(e.g., PCBs)

acidic water

from mines sediments

crop dusting

industrial wastes

city

biomedical

wastes

barnyard wastes

suburban

development

sewage

treatment plant

fertilizer runoffnuclear reactoroil pollution


Science focus: ozone shield depletion

• Ozone shield – a layer of ozone in the stratosphere that absorbs UV rays preventing them from reaching the earth

• Causes of depletion:– Chlorine atoms primarily from chlorofluorocarbons(CFCs)

• Freon used as a coolant

• Cleaning agents

• Agents used to make Styrofoam

• Concerns about loss of ozone:– Increases mutations leading to skin cancer

– Adversely affects the immune system

– Impairs crop and tree growth

– Can kill off algae and krill that sustain oceanic life


Science focus: ozone shield depletion



Ozone (Dobson Units)

110 220 330 440 550Courtesy NASA

human biology - napa valley college 105/chapt23... · human biology sylvia s. mader ... phosphorus...

Documents