The Biosphere- Chapter 8

The BIOSPHERE is the layer around the Earth containing all living organisms. To survive, these living organisms need large amounts of carbon, oxygen, nitrogen, phosphorus and sulfur. These elements are continuously circulated in BIOGEOCHEMICAL CYCLES.

BIOGEOCHEMICAL CYCLES (do not copy) Look at the word biogeochemical and see if you can figure out what these cycles are all about. Bio means "life" Geo means "earth" Chemical means "relating to chemistry"

Biogeochemical Cycles (do not copy) The carbon cycle is a biogeochemical cycle involves all the exchanges of carbon on Earth. The nitrogen cycle is a biogeochemical cycle involves all the exchanges of nitrogen on Earth. (466) The phosphorous cycle is a biogeochemical cycle involving all the exchanges of phosphorous on Earth..

Carbon Cycle (do not copy) Carbon is an element found in nature. It's in the graphite that make up the "lead" of your pencil. It's found in the shiniest diamonds and in the gasoline we use to run our cars. It's one of the most important elements found on earth. Carbon is also found in all living organisms. In fact, living things are full of carbon!

The Carbon Cycle

Carbon Cycle During photosynthesis, plants take in CO2 and water to make carbohydrates. Some of these carbohydrates are stored in the tissues of the plant. When plants are eaten by animals, digestion releases the stored carbon and other nutrients into the animal's system.

Carbon Cycle As the animal breathes out (exhales), CO2 is released into the air (atmosphere) and the cycle can begin again. This is known as respiration. Respiration is not the only way carbon makes it into the air (atmosphere). Carbon and/or CO2 is also released when dead plants and animals are decomposed and when fossil fuels are burned. Forest fires also release CO2into the atmosphere.

The Carbon Cycle Carbon moves in through the atmosphere and oceans, through organisms, and then back to the environment as dead organisms deteriorate. Carbon enters the atmosphere through respiration, fossil fuel burning, and volcanic eruptions, which release carbon from rocks deep in the earth’s crust.

The Carbon Cycle In aquatic food webs, carbon is turned into the shells and other hard parts of marine organisms. When the shelled organisms die, they sink to they bottom where they can remain buried for millions of years. This carbon may slowly be converted into “fossil fuel”: gas, petroleum coal

Human Activity is Changing the Carbon Cycle By burning fossil fuels, (coal, oil and gas) humans are changing the amount of carbon in our atmosphere. The concentration of CO2 in the atmosphere is much higher than it has been in the past and this is leading to GLOBAL WARMING. Deforestation is also increasing the concentration of CO2 in the atmosphere. (trees are no longer able to transform CO2 into O2.

The Nitrogen Cycle

The Nitrogen Cycle Of all of the nutrients influencing the growth of land plants, nitrogen is often in the shortest supply.   The atmosphere is the largest supply of nitrogen, but it is in a form that cannot be used by organisms.

The Nitrogen Cycle Nitrogen Fixation: process of converting nitrogen gas (N2) into ammonia (NH3) Bacteria that are found in the soil and on the roots of legumes undergo this process.

The Nitrogen Cycle !!! The Nitrogen Cycle Yipee!!! Nitrogen fixing bacteria can convert N2 into forms that can be used in ecosystems. The N2 is turned into ammonia NH3 by the bacteria. The ammonia is then used in the production of proteins by plants.  N2  NH3 (nitrogen fixation!) Plants use the nitrogen in their tissues, the nitrogen is then transferred to animals when they consume the plant. !!! The Nitrogen Cycle Yipee!!!

The Nitrogen Cycle Nitrogen is returned to the environment when bacteria and fungi break down nitrogen-containing wastes and the remains of plants and animals. Denitrification: conversion of nitrates into nitrogen gas (N2)

NITROGEN CYCLE(404) Nitrogen is the most common gas found in the earth's atmosphere. It is necessary for plant growth. Read page 258-259 In nitrogen fixation, bacteria found in the soil change nitrogen into substances that other organisms can use. When the fixing process is finished, free nitrogen is converted into nitrates, nitrites, and ammonia. (Humans also add nitrogen to the soil as fertilizer.)

NITROGEN CYCLE These substances can be used by plants. As the plants become food, the nitrogen can be used by animals. Animals eat plants containing usable nitrogen. That nitrogen returns to the soil as organic material (animal waste, decaying plants and animals) is decomposed by bacteria and other decomposers.

Nutrient Cycles and Acid Rain Acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. These substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain

Volcanoes and acid rain Volcanoes are a natural source of acid.

Phosphorus Cycle (466) Phosphorus is a very important component of DNA. Many animals need phosphorus to form their shells, bones and teeth. Phosphorus in the form of PO43- is being exchanged between the lithosphere, hydrosphere and living things.

Read p.260-261 Humans are changing the amount of phosphorus on the planet. Phosphate rich fertilizers and phosphate soaps are examples of what is harming the planet. Too much Phosphorus in our rivers and lakes leads to overpopulation of algae which leads to eutrophication (O2 concentrations go down).