Transcript File
CYCLING IN NATURE • Ecosystem structure is influenced by the availability of nutrients and energy. • The five main elements plants use include: carbon oxygen hydrogen nitrogen phosphorous. Cycles, Alright! • The elements essential for life tend to move in cycles. • Elements are transferred from the environment, to organisms, then back to the environment. Organisms Environment • Cold and warm ocean currents, clouds, winds, and rainfall are all a part of the global hydrologic cycle. The hydrologic cycle is driven by solar energy. • What are two ways water moves into the atmosphere? • Evaporation- water changes from liquid form to an atmospheric gas. • Transpiration: evaporation of water from leaves of plants. • It remains as water vapor, clouds, and ice crystals until it falls back to earth. How does water fall back to Earth? • Condensation- water cools and forms clouds. • Precipitation- water falls to earth and remains on land for about 10 to 120 days. • Then some of it evaporates or is carried by rivers and streams to the seas where, with evaporation, the cycle begins. • Water is an important way in which nutrients move into and out of ecosystems. As the water goes through the hydrologic cycle, it carries the nutrients with it. Raise your hand if you love the hydrologic cycle!!! Carbon Cycle http://www.youtube.com/watch?v=HrIr3xDh Q0E http://www.youtube.com/watch?v=xFE9oc_pKg • 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. • Carbon exists as gas in the atmosphere- CO2 (carbon dioxide). About half of all the carbon entering the atmosphere each year will move into two large “holding stations” or sinks or reservoirs. • The two places where most of the CO2 is housed are: 1) oceans 2) plant biomass • Each year photosynthesizers capture airborne CO2 and turn it into organic compounds, like food. • 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 Nitrogen cycle http://www.youtube.com/watch?v=ZaFVfHftz pI • 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 (sink or reservoir), but it is in a form that cannot be used by organisms. • 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. Atmospheric Nitrogen Fixation • 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!!! • Nitrogen is returned to the environment when bacteria and fungi break down nitrogencontaining wastes and the remains of plants and animals. • Denitrification: conversion of nitrates into nitrogen gas (N2)