N U T R I E N T C Y C L E S A N D E N E R G Y F L O W

Chapter 1

Objectives

In this chapter, you will:

explain that life depends on recycled matter

describe the processes of photosynthesis and cellular respiration

explain how humans can affect the cycles of matter and energy flow in ecosystems

assess the impact of fertilizers on aquatic ecosystems

observe the chemistry of photosynthesis

model acid precipitation

determine the impact of excess fertilizers on plants

How Disturbed is Too Disturbed?

1.1 Sustainability (p.7)

ecosystem: all the interacting parts of a biological community and its environment

sustainable ecosystem:

capable of withstanding pressure

gives support to a variety of organisms

The Mystery of Easter Island

The Mystery of Easter Island

humans inflict catastrophic changes on an ecosystem

greatly affect an ecosystem’s sustainability

Ecosystems and Survival (p.8)

Ecosystems and Survival

All organisms require sustainable ecosystems for survival

Many depend on more than one ecosystem.

Examples:

Ruby-throated hummingbirds

American eel

Parts of an Ecosystem (p.9)

Parts of an Ecosystem

Every ecosystem has 2 parts:

1) Biotic: living parts of an ecosystem

eg. plants, animals, micro-organisms

2) Abiotic: non-living parts

eg. water, oxygen, light, nutrients, soil

Biotic Interactions in an Ecosystem (p.10)

Biotic Interactions in an Ecosystem (p.10)

Biotic Interactions in an Ecosystem

1. Symbiosis: members of 2 different species live together in a close association

2. Predation: one organism consumes another organism for food

3. Competition: two or more organisms compete for the same resource in the same location at the same time

Abiotic Characteristics of an Ecosystem (p.12)

Abiotic Characteristics of an Ecosystem (p.12)

Abiotic Characteristics of an Ecosystem

1. Water: to survive; regulate body temperature, get rid of wastes, marine organisms

2. Oxygen: for life processes; aquatic organisms get oxygen from water

3. Light: for photosynthesis

4. Nutrients: to grow, eg. nitrogen, phosphorus

5. Soil: nutrients for plants, habitat for micro-organisms

Cycling of Matter and Earth’s Spheres (p.13)

Cycling of Matter and Earth’s Spheres (p.13)

Ecological processes:

move matter between biotic and abiotic parts

continuous cycles

• lithosphere: the hard part of Earth’s surface.

• hydrosphere: all of the water found on Earth

• atmosphere: layers of gas above Earth’s surface.

• biosphere: regions of Earth where living organisms exist

Nutrient cycles (p.14)

Nutrients:

chemical essential to living things

cycled through ecosystems

1. The Water Cycle (p.14)

1. The Water Cycle (p.14)

1. The Water Cycle (p.14)

1. sun evaporates water

2. form clouds, then precipitation

3. river system and ground water lead to ocean

4. meanwhile, erodes rocks and picks up other materials

5. absorbed by plants, animals

2. The Carbon Cycle (p.14)

2. The Carbon Cycle (p.14)

2. The Carbon Cycle (p.14)

1. plants use carbon dioxide (CO2) to make sugars

2. organisms break down sugar, release energy and CO2

3. organism die and decomposed

4. remains of organisms converted into fossil fuels

5. humans burn fossil fuels for energy

3. The Nitrogen cycle (p.16)

3. The Nitrogen cycle (p.16)

3. The Nitrogen cycle (p.16)

Terrestrial ecosystem: land-based

Aquatic ecosystem: water-based (fresh or salt water)

3. The Nitrogen cycle (p.16)

In terrestrial ecosystems:

soil bacteria convert nitrogen gas into ammonium

other soil bacteria convert ammonium into nitrate

In aquatic ecosystems:

cyanobacteria convert nitrogen gas into ammonium

Human fertilize soil add ammonium and nitrate to soil

Plants absorb ammonium and nitrate, pass along food chain

Bacteria change nitrate to nitrogen gas

Volcanic eruptions and burn fossil fuel release ammonia containing nitrogen into the air

Excess nitrate and ammonium become part of rocks

4. The Phosphorus Cycle (p.17)

4. The Phosphorus Cycle (p.17)

4. The Phosphorus Cycle (p.17)

Terrestrial ecosystem:

Phosphorus is stored in rocks and sediments as phosphate (lithosphere)

Weathering, rocks small rocks soil

Human fertilizers and detergents release phosphate into soil

Absorbed by plants, move through food chain

Bacteria break down dead organism and waste, release phosphate into soil

Aquatic ecosystem:

Leaching and run-off , phosphate enter aquatic system

Absorbed by plants, move through food chain

Bacteria break down dead organism and waste, release phosphate into water

Phosphate settles to bottom of water bodies

Human Activities and Nutrient Cycles (p.18)

Human Activities and Nutrient Cycles

Human Activities and Nutrient Cycles

Eutrophication:

a process

nutrient levels in aquatic ecosystems increase,

primary producers (algae) increases

oxygen in water decreases

Slow naturally

Fast with human activities:

run-off contains high amounts of agricultural fertilizers (nitrates and phosphates) causes eutrophication

Science and Social Policy (p. 19)

Science and Social Policy (p. 19)

Great Lakes Water Quality Agreement

“restore and maintain the chemical, physical, and biological integrity of the waters of the Great Lakes Basin Ecosystem.”

Signed by Canada and the US

Environmental Farm Plan

Reduce phosphorus in run-off

Anti-pesticide By-laws

Banned non-essential pesticide