3.3 CYCLES OF MATTER
Unlike the one way flow of energy, matter is recycled within and between ecosystems. Element , chemical compounds, and other forms of matter are passed form one organism to another and from one part of the biosphere to another through biogeochemical cycles. Matter can cycle through the biosphere because biological systems do not use up matter, they transform it. The process by which water changes from liquid form to gas form is called evaporation. Water can also enter the atmosphere by evaporating from the leaves of plants in the process of transpiration. All of these process can be found in the water cycle.
All the chemical substances that an organism needs to sustain life are its nutrients. Every living organism needs nutrients to build tissues and carry out essential life functions. Like water, nutrients are passed between organisms and the environment through biogeochemical cycles
Carbon is the key ingredient of living tissue, because carbon is and important component of animal skeletons. Carbon is also an important component in the atmosphere and is taken in and given out by plants and animals. Four main types of processes move carbon through its cycle:
- Biological process such as photosynthesis and a few others such as respiration release carbon.
- Geochemical process, such as erosion and volcanic activity release carbon.
- Mixed biogeochemical process, such as the decomposition of dead organisms store carbon under the ground.
- Human activities such as mining release carbon into the atmosphere.
All organisms require nitrogen to make amino acids, which in turn used to build proteins. Such bacteria, which live i the soil and on the roots of plants called legumes, convert nitrogen gas into ammonia in a process known as nitrogen fixation. Other soil bacteria convert nitrates into nitrogen gas in a process called denitrification. This process releases nitrogen into the atmosphere once again.
The phosphorus cycle is essential to living organisms because it form part of important life sustaining DNA and RNA. The phosphorus does not go in the atmosphere but only stay on land and will soon dissolve in the ocean.
Primary productivity is the rate at which organic matter is created by producers. Limiting nutrient is when an ecosystem is limited by a single nutrient that is scarce or cycles slowly. Because of this, many farmers use fertilizers. An algal bloom is when an aquatic ecosystem receives a large input of a limiting nutrient. There are more nutrients available so the population grows more quickly.
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