introduction to environmental science · 1 ecological concepts l the science of ecology n the study...

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Introduction to environmental science

Chapter 5

Li Guangming College of Environmental Science and Engineering

Tongji University

1350 196 7237

[email protected]

Chapter 5

Intractons: Environments and organisms

15/4/8 Introduction to environmental science - Chapter 5 2

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1 Ecological concepts

l  The science of ecology

n  The study of the way organisms interact with

each other and with their nonliving

surroundings

n  Atoms-molecules-individual organisms-groups

of interacting organisms-ecological systems


l  The Nature of ecology

Ecosystem organization

Organisms

Populations

Communities

Ecosystems

Biosphere


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Levels of

organization of

matter, according

to size and

function

Organism

Species

Population

Community


The environment affec ng an organism

•  Abio c（⾮⽣命）

• The flow of energy • The physical factors, such as climate, temperature,

precipita on, seasonal distribu on, type of soil

and

so on • The supply of molecules required for its life

func ons •  Bio c（⽣物的） 15/4/8 Introduction to environmental science - Chapter 5 6

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2 Limiting factors

l  Many plants are limited by scarcity of water or specific soil nutrients

l  Animals may be limited by climate or the availability of a specific food

l  For example

n  Snakes and lizards are limited to the warmer parts of

the world

n  The limiting factor for many species of fish is the

amount of dissolved oxygen in the water


3 Life and Earth’s life support systems

l  What is life?

n  The cell is the basic unit of life

n  All forms of life

•  Have highly organized internal structure and organization

•  Have characteristic types of DNA molecules in each cell

•  Can capture and transform matter and energy from their

environment in order to survive, grow and reproduce


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Protein

construction

Generalized structure of a

eukaryotic cell（真核细胞）

The parts and internal structure

of cells in various types of

organisms such as plants and

animals differ somewhat from

this generalized model



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•  Can maintain favorable internal conditions despite

changes in their external environment if not

overwhelmed

•  Arise through reproduction ---- the production of offspring

by one or more parents ---- and in turn are capable of

reproduction

•  Can adapt to external change by mutation ---- random

changes in their DNA molecules ---- and through

combinations of existing genes during reproduction


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l  Earth: a dynamic

plant

n  The atmosphere

n  The hydrosphere

n  The lithosphere

n  The ecosphere


l  Energy flow, matter cycling, and gravity

n  The one way flow of high-quality (usable) energy

n  The cycling of matter required by living

organisms through parts of the ecosphere

n  Gravity


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l  The sun: source of energy for life

n  A middle aged star that lights and warms the

planet



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l  Nutrient cycles

n  Any chemical element or compound an organism must take in to live, grow, or reproduce

n  Macronutrients

•  Carbon, oxygen, hydrogen, nitrogen, phosphorous, sulfur, calcium, magnesium, potassium, and their compounds

n  Micronutrients

•  Iron, copper, zinc, chlorine, and iodine

n  Nutrient cycles (biogeochemical cycles)

•  These nutrient elements and their compounds are continuously cycled from the nonliving environment to living organisms, and back to the nonliving environment



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4 Ecosystem components


Ecosystems rarely have boundaries.


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l  Biodiversity

l  Types of organism

n  Monera（⽆核原⽣物） (bacteria and cyanobacteria（蓝

菌）) are single-celled, prokaryotic（原核⽣物）, microscopic

organisms

n  Protista（原⽣⽣物） (prosists) are mostly single-celled

eukaryotic（真核的） organisms such as diatoms, amoebas

n  Fungi are mostly many-celled eukaryotic organisms such as

mushrooms, mold（真菌）, and yeasts（酵⺟）

n  Plantae (plants)

n  Animalia (animals): invertebrates（⽆脊髓）,

vertebrates（脊髓）


Monera原核⽣物

Protista原⽣⽣物

Fungi真菌

Plantae植物

Animalia动物


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l  Living components of ecosystems

Major components of a freshwater pond system


Major components of an ecosystem in a field


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n  Producers (autotrophs)

•  Can make the organic nutrients they need from

simple inorganic compounds in their environment

n  Consumers (heterotrophs)

•  Herbivores (plant-eaters) are called primary

consumers

•  Carnivores (meat-eaters) are secondary consumers

–  Tertiary (higher-level) consumers feed only on other

carnivores

•  Omnivores eat both plants and animals, such as

pigs, rats, foxes, cockroaches, and humans


•  Detritivores (decomposer and detritus feeder) live off detritus, parts of dead organisms and cast-off fragments and wastes of living organisms


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•  Decomposers digest the complex organic molecules

in detritus into simpler inorganic compounds and

absorb the soluble nutrients

–  These decomposers ---- mostly bacteria and fungi ---- are an

important source of food for worms and insects in the soil

and water

–  Detritus feeders, such as crabs, carpenters ants, termites,

and earthworms, extract nutrients from partly decomposed

organic matter

l  Nonliving parts of ecosystems

n  Sunlight and shade

n  Average temperature and temperature range

n  Average precipitation and its timing

n  Wind


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n  Latitude

n  Altitude

n  Nature of the soil

n  Fire

n  Water currents

n  Amounts of suspended solid material

n  Important chemical factors affecting

ecosystems

•  Supply of water and air in the soil

•  Supply of plant nutrients dissolved in soil moisture

and in water

•  Level of toxic substances dissolved in soil moisture

and in water

•  Salinity of water

•  Level of dissolved oxygen


l  Tolerance ranges of species


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A variety of factors can affect the number of organisms in a population.

Sometimes one factor, known as a limiting factor, is more important in regulation population growth than other factors.


5 Energy flow in ecosystems

l  Food chains and food webs


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Greatly simplified food web in the

Antarctic.

There are many participants,

including an array of decomposer

organisms


l  Ecological pyramids


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Energy Input:

1,700,000 kilocalories Incoming solar energy

not harnessed

1,679,190

(98.8%)

Energy 20,810

Transfers (1.2%)

Producers Waste, Metabolic heat,

remains export

4,245 3,368 13,197 Top carnivores 21

Carnivores

Decomposers/detritivores

5,060 Herbivores

383 Herbivores

720

90

383 2,265

272

3,368

Carnivores Producers 20,810

21

Top carnivores

5 16 Decomposers, detritivores

Energy Output

Total Annual Energy Flow 20,810 + 1,679,190

1,700,000 (100%)


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l  Productivity of producers

n  Gross primary productivity

•  The rate at which an ecosystem’s producers capture and

store chemical energy as biomass

n  Net primary productivity

•  The producers must use some of this biomass to stay

alive

Rate at which producers produce

chemical energy

stored in biomass

through

Rate at which producers use

chemical energy

stored in biomass

through aerobic

respiration

Net primary productivity = -

photosynthesis


Estimated average net primary productivity in major life zones and ecosystems.

Values are given in kilocalories of produced per square meter per year


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6 Matter cycling in ecosystems

l  Hydrologic cycle (water cycle)

n  Main processes

•  Evaporation (water à water vapor)

•  Transpiration (soil à leaves à evaporation)

•  Condensation (water vapor à droplets)

•  Precipitation (rain, sleet, hail, and snow)

•  Infiltration (water à soil)

•  Percolation (downward flow)

•  Runoff (downslope)


The water cycle is powered by energy from sun and gravity


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n  How are human activities affecting the water

cycle?

•  Withdraw large quantities fresh water from streams,

lakes, and underground sources.

–  In some heavily populated or heavily irrigated areas,

withdraws has led to groundwater depletion or intrusion of

ocean salt water into underground water supplies


•  Clearing vegetation from land for agriculture, mining,

road and building construction, and other activities

–  Increase runoff

–  Reduce infiltration

–  Increases the risk of flooding

–  Accelerate soil erosion and landslides

•  Modifying water quality

–  Adding nutrients (phosphates and nitrate found in fertilizers)

–  Other pollutants

–  Changing ecological processes that purify water naturally


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l  Carbon cycle

n  Basic block of the carbohydrates, fats, proteins,

and other organic compounds for life

Diffusion between

atmosphere and

ocean

Atmosphere (mainly carbon dioxide)

Volcanic action

Bicarbonate and

carbonate

dissolved in ocean

water

Combustion of

fossil

Terrestrial rocks

Combustion Photo-

synthesis

Aerobic

respiration of wood (for

clearing land,

or for fuel Photo-

synthesis Aerobic

respiration Land food

webs Producers,

consumers,

decomposers,

detritivores

Sedimentation Weatheri

ng Marine food

webs Producers, consumers,

decomposers, detritivores Soil water

(dissolved carbon) Peat,

fossil

fuels

Death & other

sedimentation

Uplifting over

geological time Death, burial,

compaction over geologic time Sedimentation Leaching

runoff Marine sediments, including

formations with fossil fuels


n  Carbon dioxide

•  0.036% of the volume of the troposphere

•  A key component of nature’s thermostat

•  If the carbon cycle removes too much CO2 from the

atmosphere, the atmosphere will cool

•  If the cycle generates too much, the atmosphere will

get warmer

•  Even slight changes in the carbon cycle can affect

climate and ultimately the types of life that can exist

on various parts of the planet


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n  How are human activities affecting the carbon

cycle?

•  Clearing tree and other plants that absorb CO2

through photosynthesis

•  Adding large amounts of CO2 by burning fossil fuels

and wood


Carbon dioxide in the

atmosphere

rapid rise from human

activities


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Regional pattern of warming over last 50 years


永久冻⼟泥炭沼⼈类活动包合物海洋植被

植被破坏

导致

CO2吸收能⼒下降

永久冻⼟融化将导致其蕴含的 CO2被释放出来

海绵质⼟壤⼀旦干涸有机质被细菌分解将释放CO2

燃烧化⽯燃料排放⼤量 CO2

在⽔温升⾼作⽤下，海底 CH4

⼤量释放

⽔温升⾼溶解的放出来

，， CO2释

l  温室效应严重威胁着整个⼈类。据预计，海平⾯将升⾼，许多⼈⼝稠密的地区（如孟加拉国、中国沿海地带以及太平洋和印度洋上的多数岛屿）都将被⽔淹没

l  ⽓温的升⾼也将对农业和⽣态系统带来严重影响。据预计，1990-2010年，亚洲和太平洋地区的能源消费将增加⼀倍，拉丁美洲的能源消费将增加50-70%


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Global warming as entertainment …

2004


l  Nitrogen cycle

n  Nitrogen is the atmosphere ’s abundant element, which chemically unreactive nitrogen gas making up 78% of the volume of the troposphere

n  N can not be absorbed and used directly as a 2

nutrient by multicellular plants or animals

n  Atmospheric electrical discharges in the form of lightning and certain bacteria in the soil and aquatic systems convert nitrogen gas into compounds that can enter food webs as part of nitrogen cycle


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l  Nitrogen cycle: bacteria in action


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n  How are human activities affecting the nitrogen cycle?

•  Adding large amounts of nitric oxide (NO) into the atmosphere

when we burn any fuel

–  NO2àHNO3

–  Damage and weaken trees

–  Upset aquatic ecosystems

–  Corrode metals

–  Damage marble, stone and other building materials

•  Adding nitrous oxide (N2O) to the atmosphere through the

action of anaerobic bacteria on livestock wastes and

commercial inorganic fertilizers applied to the soil

–  Help warm the atmosphere

–  Contribute to depletion of the earth’s ozone shield


n  Removing nitrogen from topsoil

•  Harvest nitrogen-rich crops

•  Irrigate crops

•  Burn or clear grassland and forest before planting crops

n  Adding nitrogen compounds to aquatic ecosystems

in agricultural runoff and discharge of municipal

sewages

•  Stimulates rapid growth of photosynthesizing algae and

other aquatic plants

•  The subsequent breakdown of dead algae by aerobic

decomposers can

–  Deplete the water of dissolved oxygen

–  Disrupt aquatic systems by killing some types of fish and other

oxygen using organisms


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n  Accelerating the deposition of acidic nitrogen

compound (such as NO2 and HNO3) from the

atmosphere onto terrestrial ecosystems

•  Stimulate the growth of weedy plant species, which

can outgrow and perhaps eliminate other plant

species


l  Phosphorus cycle


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n  How are human activities affecting the

phosphorus cycle?

•  Mining large quantities of phosphate rock for use in

commercial inorganic fertilizers and detergents

•  Reducing the available phosphate in tropical forests

by removing trees

•  Adding excess phosphate to aquatic system in

–  Runoff of animal wastes from livestock feedlots

–  Runoff of commercial phosphate fertilizers from cropland

–  Discharge of municipal sewage


l  Sulfur cycle

n  How are human activities

affecting the sulfur cycle?

•  Burning sulfur-containing

coal and oil to produce

electric power, producing

about

human

dioxide

two-thirds of the

inputs of sulfur

•  Refining sulfur-containing

petroleum to make gasoline,

heating oil, and other useful

products

•  Using smelting to convert

sulfur compounds of metallic

minerals into metals such as

copper, lead, and zinc


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7 Roles of species in ecosystems

l  Types of species in ecosystems

n  Native species

n  Immigrant, or alien species

n  Indicator species

•  Which serve as early warnings that a community or an

ecosystem is being damaged.

n  Keystone species

•  Affect many other organisms in an ecosystem


l  Niche（⽣境）

n  The ecological niche, or simply niche of a

species is its total way of life or its role in an

ecosystem

n  Specialist species

•  They may be able to live in only one type of habitat,

tolerate only a narrow range of climatic and other

environmental conditions or use only one or a few

types of food

n  Generalist species

•  Have broad niches


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8 Interactions between species

l  Ways species interact

n  Interspecific competition（中间竞争）

n  Predation（掠夺）

n  Parasitism（寄⽣）

n  Mutualism（互利共⽣）

n  Commensalism（共栖）


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谢谢！

THANK YOU FOR YOUR ATTENTION


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introduction to environmental science · 1 ecological concepts l the science of ecology n the study...

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