Chapter 5 Notes Environmental Science

Objectives  Describe the short-term and long-term process of the carbon cycle.  Identify one way that humans are affecting the carbon cycle.  List the three stages of the nitrogen cycle.  Describe the role that nitrogen-fixing bacteria play in the nitrogen cycle.  Explain how the excess use of fertilizer can affect the nitrogen and phosphorus cycles.

Open Activity  Describe what you think the cycling of matter means and how does it help us?

Open Activity  Law of Conservation of Energy  Law of Conservation of Matter  Matter and energy cannot be created nor destroyed instead it moves through the environment in different forms

Carbon Cycle  The carbon cycle is the movement of carbon from the nonliving environment into living things and back to the environment.  Carbon is the essential component of proteins, fats, and carbohydrates, which make up all organisms.

Carbon Cycle

The Carbon Cycle  Carbon is a key ingredient of living tissue.  4 types of processes move carbon through its cycle.

1. Biological processes  Photosynthesis, respiration, and decomposition take up and release carbon and oxygen

2. Geochemical processes  Erosion and volcanic activity release carbon dioxide to the atmosphere and oceans.

3. Biogeochemical processes  Decomposition of dead organic matter under pressure turns into coal and petroleum and store carbon underground.

4. Human Activities  Mining, cutting and burning forests, and burning fossil fuels all release carbon dioxide into the air.  Carbon dioxide is a greenhouse gas along with water vapor and other gases.  Greenhouse gases absorb and reradiate infrared energy, warming Earth.

Carbon dioxide in the air

Green plants use carbon dioxide to make their food

Carbon dioxide in the air Green plants use carbon dioxide to make their food Green plants are eaten by animals

Carbon dioxide in the air Green plants use carbon dioxide to make their food Green plants are eaten by animals respiration

carbon dioxide in the air green plants use carbon dioxide to make their food green plants are eaten by animals respiration dead remains of plants and animals decay by fungi and bacteria

The Nitrogen Cycle  The nitrogen cycle is the process in which nitrogen circulates among the air, soil, water, plants, and animals in an ecosystem.  All organisms need nitrogen to build proteins, which are used to build new cells.  Nitrogen makes up 78 percent of the gases in the atmosphere.

The nitrogen cycle  They cannot use the nitrogen in the air  The nitrogen in the air must be changed to nitrates before plants can use it.

The Nitrogen Cycle

The nitrogen cycle  Animals get their nitrogen by eating plants.

The nitrogen cycle  Nitrogen-fixing bacteria living in these nodules change nitrogen in the air into nitrates.

The nitrogen cycle  The nitrogen- fixing bacteria are essential to maintain the fertility of the soil.  Without them… food yields would rapidly fall.

Decomposers and the Nitrogen Cycle  Nitrogen stored within the bodies of living things is returned to the nitrogen cycle once those organisms die.  Decomposers break down decaying plants and animals, as well as plant and animal wastes.  After decomposers return nitrogen to the soil, bacteria transform a small amount of the nitrogen into nitrogen gas, which then returns to the atmosphere to complete the nitrogen cycle.

nitrogen in the air

fertilizers

nitrogen in the air fertilizers waste substances e.g. faeces

nitrogen in the air fertilizers waste substances e.g. faeces lightning

nitrogen in the air fertilizers waste substances e.g. faeces lightning

nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil

nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover

nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover

nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover dead remains of plants and animals

nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover dead remains of plants and animals nitrates in the soil

nitrogen in the air fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover dead remains of plants and animals nitrates in the soil

fertilizers waste substances e.g. faeces lightning Nitrogen-fixing bacteria in the soil Nitrogen-fixing bacteria in the root nodules of clover dead remains of plants and animals nitrates in the soil denitrifying bacteria in the soil break down nitrates

Phosphorus Cycle  Very slow cycle.  Almost all found in the ground.

The Phosphorus Cycle  Phosphorus is an element that is part of many molecules that make up the cells of living organisms.  Plants get the phosphorus they need from soil and water, while animals get their phosphorus by eating plants or other animals that have eaten plants.  The phosphorus cycle is the cyclic movement of phosphorus from the environment to organisms and then back to the environment.

The Phosphorus Cycle

 Phosphorus may enter soil and water when rocks erode. Small amounts of phosphorus dissolve as phosphate, which moves into soil, water, and groundwater.  Plants absorb phosphates in the soil through their roots.  Some phosphorus washes off the land and ends up in water bodies.  Because many phosphate salts are not soluble in water, they sink to the bottom and accumulate as sediment.

Fertilizers and the Nitrogen and Phosphorus Cycles  Fertilizers, which people use to stimulate and maximize plant growth, contain both nitrogen and phosphorus.  Excessive amounts of fertilizer can enter terrestrial and aquatic ecosystems through runoff.

Algal bloom  Excess nitrogen and phosphorus can cause rapid growth of algae.  Excess algae can deplete an aquatic ecosystem of important nutrients such as oxygen, on which fish and other aquatic organisms depend.