Other elements and compounds also exist in cycles. Elements pass along food chains when animals eat plants and other animals. Many humans eat protein in the form of meat from other animals. The ocean is an example of a reservoir for water. Reservoirs are components of a geochemical cycle that hold elements or water for a relatively long period of time. Although the water on Earth is billions of years old, individual water molecules are always moving through the water cycle.
It is shown in Figure 1. Like other biogeochemical cycles, there is no beginning or end to the water cycle. It just keeps repeating. During the cycle, water occurs in its three different states: gas water vapor , liquid water , and solid ice. Processes involved in changes of state in the water cycle include evaporation, sublimation, and transpiration.
Figure 1: This diagram of the water cycle shows where water is stored and the processes by which water moves through the cycle, including evaporation, condensation, and precipitation. The sun is the driving force behind the water cycle. It heats oceans, lakes, and other bodies of water, causing water to evaporate from the surface and enter the atmosphere as water vapor.
Water in soil also evaporates easily. In addition, the sun heats ice and snow, causing it to turn directly into water vapor in the process of sublimation. Water also evaporates from the above-ground parts of plants. Transpiration is another process by which plants lose water.
Transpiration occurs when stomata in leaves open to take in carbon dioxide for photosynthesis and lose water to the atmosphere in the process.
The water cycle plays an important role in climate. For molecules of liquid water to change to water vapor, kinetic energy is required, or the energy of movement. As faster-moving molecules evaporate, the remaining molecules have lower average kinetic energy, and the temperature of ocean water thus decreases.
The primary way that oceans slow global warming is by heat uptake which warms ocean water and removes some energy from the atmosphere. Rising air currents carry water vapor from all these sources into the atmosphere. As the water vapor rises higher into the atmosphere or is carried toward the poles by winds, the air becomes cooler. Cooler air cannot hold as much water vapor, so the water vapor condenses into tiny water droplets around particles in the air.
The tiny water droplets form clouds. Air currents cause the tiny water droplets in clouds to collide and merge into larger droplets. When water droplets in clouds become large enough to fall, they become precipitation. Most precipitation falls back into the ocean. Precipitation that falls at high altitudes or near the poles can accumulate as ice caps and glaciers.
These masses of ice can store frozen water for hundreds of years or longer. Rain that falls on land may either soak into the ground, which is called infiltration , or flow over the land as runoff. Snow that falls on land eventually melts, with the exception of snow that accumulates at high altitudes or near the poles. Like rain water, snowmelt can either infiltrate the ground or run off.
Water that infiltrates the ground is called groundwater. Groundwater close to the surface can be taken up by plants. Alternatively, it may flow out of the ground as a spring or slowly seep from the ground into bodies of water such as ponds, lakes, or the ocean. Groundwater can also flow deeper underground. It may eventually reach an aquifer. An aquifer is an underground layer of water-bearing, permeable rock.
Groundwater may be stored in an aquifer for thousands of years. Wells drilled into an aquifer can tap this underground water and pump it to the surface for human use.
Runoff water from rain or snowmelt eventually flows into streams and rivers. The water is then carried to ponds, lakes, or the ocean. From these bodies of water, water molecules can evaporate to form water vapor and continue the cycle.
Finally, decomposition returns phosphate to the soil, as it does other nutrients. Fertilizers contain additional nitrogen and phosphorus. However, excessive use of fertilizer can lead to undesired plant growth in other ecosystems via runoff. Algal blooms are particularly dangerous to local ecosystems, since they can drain vital nutrients from the ecosystem. Algal blooms often occur when excess nitrogen and phosphorus is dumped into water sources. This means that other nutrients are lost, which damages the long-term stability of that ecosystem.
Lastly, plants that adapted to low levels of nitrogen can be put at risk of extinction, as they are not adapted to survive in high-nitrogen ecosystems. Cycles of Nature Matter, as well as energy, moves through an ecosystem and is constantly recycled.
Nitrogen, water, oxygen and carbon are cycled globally. The Carbon Cycle The carbon cycle is the movement of carbon from the nonliving environment into living things and back Carbon is the essential component. Recycling Matter All things living are made of matter Total amount of matter on Earth is limited, so it must be recycled again.
Cycles of Matter. Recycling in the Biosphere Energy and matter move through the biosphere very differently. Unlike the one-way flow of energy, matter. Cycles of Matter In an Hour or Less!!!!. Nutrient Cycles Miss Schwippert. The overall effect is that carbon is constantly recycled in the dynamic processes taking place in the atmosphere, at the surface and in the crust of the earth.
For example, the combustion of wood transfers carbon dioxide to the atmosphere. The carbon dioxide is taken in by plants and converted to nutrients for growth and sustenance. Animals eat the plants for food and exhale carbon dioxide into the atmosphere when they breathe. Atmospheric carbon dioxide dissolves in the ocean where it eventually precipitates as carbonate in sediments.
The ocean sediments are sub ducted by the actions of plate tectonics , melted and then returned to the surface during volcanic activity. Carbon dioxide gas is released into the atmosphere during volcanic eruptions. Some of the carbon atoms in your body today may long ago have resided in a dinosaur's body, or perhaps were once buried deep in the earth's crust as carbonate rock minerals. The main carbon cycling processes involving living organisms are photosynthesis and respiration.
These processes are actually reciprocal to one another with regard to the cycling of carbon: photosynthesis removes carbon dioxide from the atmosphere and respiration returns it.
A significant disruption of one process can therefore affect the amount of carbon dioxide in the atmosphere. During a process called photosynthesis , raw materials are used to manufacture sugar. Photosynthesis occurs in the presence of chlorophyll , a green plant pigment that helps the plant utilize the energy from sunlight to drive the process. Although the overall process involves a series of reactions, the net reaction can be represented by the following:.
The sugar provides a source of energy for other plant processes and is also used for synthesizing materials necessary for plant growth and maintenance. The net effect with regard to carbon is that it is removed from the atmosphere and incorporated into the plant as organic materials. The reciprocal process of photosynthesis is called respiration.
The net result of this process is that sugar is broken down by oxygen into carbon dioxide and water. The net reaction is:. This process occurs not only in plants, but also in humans and animals. Unlike photosynthesis, respiration can occur during both the day and night. During respiration, carbon is removed from organic materials and expelled into the atmosphere as carbon dioxide. Another process by which organic material is recycled is the decomposition of dead plants and animals.
During this process, bacteria break down the complex organic compounds. Carbon is released into the soil or water as inorganic material or into the atmosphere as gases. Decomposed plant material is sometimes buried and compressed between layers of sediments. After millions of years fossil fuels such coal and oil are formed. When fossil fuels are burned, the carbon is returned to the atmosphere as carbon dioxide.
The carbon cycle is very important to the existence of life on earth. The daily maintenance of living organisms depends on the ready availability of different forms of carbon. Fossil fuels provide an important source of energy for humans, as well as the raw materials used for manufacturing plastics and other industrially important organic compounds.
The component processes of the carbon cycle have provided living things with the necessary sources of carbon for hundreds of millions of years. If not for the recycling processes, carbon might long ago have become completely sequestered in crustal rocks and sediments, and life would no longer exist.
Human activity threatens to disrupt the natural cycle of carbon. Two important ways by which humans have affected the carbon cycle, especially in recent history, are: 1 the release of carbon dioxide into the atmosphere during the burning of fossil fuels, and 2 the clearing of trees and other plants deforestation that absorb carbon dioxide from the atmosphere during photosynthesis.
The net effect of these actions is to increase the concentration of carbon dioxide in the atmosphere. It is estimated that global atmospheric carbon dioxide is increasing by about 0.
Carbon dioxide is a greenhouse gas i. The heat is instead absorbed by the atmosphere. Many scientists believe that the increased carbon dioxide concentration in the atmosphere is resulting in global warming. This global warming may in turn cause significant changes in global weather, which could negatively affect all life on earth.
However, increased photosynthesis resulting from the increase in the concentration of carbon dioxide may somewhat counteract the effects.
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