CYCLES OF MATTER NATURAL WORLD

Objectives Describe how matter cycles between the living and nonliving parts of an ecosystem. Explain why nutrients are important in living systems. Describe how the availability of nutrients affects the productivity of ecosystems.

Vocabulary Biogeochemical Cycle Evaporation Transpiration Nutrients Nitrogen Fixation Denitrification Primary Productivity Limiting Nutrient Algal Bloom

Recycling in the Biosphere Unlike the one-way flow of energy, matter is recycled within and between ecosystems. Matter can be recycled, because biological systems do not use up matter, they only change it from one form to another.

The Water Cycle The water cycle involves the movement of water between the ocean, atmosphere, and land. Evaporation is process by which water changes from liquid form to atmospheric gas. Transpiration is the process of water entering the atmosphere by evaporating from the leaves of plants.

The Water Cycle Most of the water on Earth is held in the ocean. The sun causes the water to evaporate. As the water vapor cools it condenses into droplets. When the droplets become large enough they return to the Earth’s surface. On land, much of the precipitation runs along the surface until it enters a river or stream that carries the runoff back to an ocean or lake. Water can enter plants through their roots. The water cycle begins all over again.

Nutrient Cycles Nutrients include all the chemical substances that an organism requires to live. Every organism needs nutrients to grow and carry out essential life functions. Like water nutrients are passed between organisms through cycles. The three nutrient cycles that play especially prominent roles in the biosphere are the carbon cycle, the nitrogen cycle, and the phosphorus cycle.

The Carbon Cycle Carbon is the key ingredient in all living organisms. Carbon is also found in the oceans, in the air, and in certain types of rocks. Scientists believe the Earth contains approximately 49,000 gigatons of carbon. However, less than 1 percent actively circulates within the biosphere. 71% is in the oceans, 22% in fossils, 3% in dead organic matter, and 3% in terrestrial ecosystems.

Carbon Cycle There are four different kinds of processes involved in the carbon cycle… Biological Geochemical Biogeochemical Human Impact

Biological Processes Carbon in the atmosphere is carbon dioxide. Plants take in carbon dioxide and use the carbon to build carbohydrates during photosynthesis. The carbohydrates are passed along the food web to the consumers. The carbohydrates are broken down by animals during respiration and returned to the atmosphere as carbon dioxide.

Geochemical Processes Carbon Dioxide gas is released into the atmosphere by erupting volcanoes.

Biogeochemical Processes These are caused by the burial of carbon-rich remains of organisms and their conversion into coal and petroleum (fossil fuels) by the pressure of the overlying earth.

Human Impact Humans affect the carbon cycle by mining, burning fossil fuels, and destroying forests.

Carbon Cycle CO 2 in Atmosphere CO 2 in Ocean

STOP HERE End of cycles day one

Nitrogen Cycle All organisms require nitrogen to make amino acids, which in turn are used to build proteins. Nitrogen gas (N 2 ) makes up 78% of our atmosphere. Nitrogen-containing substances such as ammonia (NH 3 ), nitrates (NO 3- ), and nitrites (NO 2- ) are found in dead and decaying organic matter. Humans add nitrogen to the biosphere in the form of nitrate - a major component of plant fertilizers.

Nitrogen Cycle Only certain types of nitrogen-fixing bacteria can use the gasseous form of nitrogen (N 2 ). Nitrogen Fixation is when nitrogen-fixing bacteria convert atmospheric nitrogen into ammonia. Nitrogen-fixing bacteria live in the soil, and on the roots of plants called legumes (bean plants).

Nitrogen Cycle Producers can use the nitrogen in the soil to make proteins. Consumers eat the producers and reuse the nitrogen to make their own proteins. When organisms die decomposers return nitrogen to the soil as ammonia. Some of the ammonia will be taken up again by producers. Denitrification, other soil bacteria will convert the nitrates into nitrogen gas (N 2 ) returning it to the atmosphere.

Nitrogen Cycle N 2 in Atmosphere NH 3 NO 3- and NO 2-

Phosphorus Cycle Phosphorus is essential to living organisms because it forms part of important life-sustaining molecules DNA and RNA. Inorganic phosphate makes up the the backbone of DNA and RNA, the molecules of heredity.

Phosphorus Cycle Phosphorus does not enter the atmosphere. It remains mostly in the rocks, soil and the ocean as its inorganic form (P i ).

Phosphorus Cycle When plants absorb phosphate from the soil or from water, the plants bind the phosphate into organic compounds. Organic phosphate travels through the food web. Organic compounds are defined as compounds that contain carbon.

Nutrient Limitation Primary Productivity is the rate at which organic matter is created by producers. A Limiting Nutrient when a nutrient is in short supply and it limits the growth of the ecosystem. Algal Bloom when an aquatic ecosystem receives a large input of a limiting nutrient it results in a rapid growth of algae.