What is the nitrogen cycle?
The nitrogen cycle is the process by which toxic ammonia (NH3) is converted into nitrites (NO2-), and then into nitrates (NO3-) by the production of beneficial bacteria. In aquatic systems, especially captive environments, the nitrogen cycle must be allowed to complete before inhabitants are introduced; this is referred to as cycling the tank. Once the nitrogen cycle has been established in a new tank, it is a continuous conversion process (hence the word cycle in nitrogen cycle). Because captive environments are typically very tiny compared to natural habitats, this biological cycle will at some point require some assistance in the form of tank maintenance (i.e. gravel vacuuming, water changes, filter changes etc.), which will be discussed later in the article. When an aquatic tank is first setup, the water is clean and void of the necessary bacteria to enact the nitrogen cycle.
Like all living creatures, fish give off waste products (pee and poo). These nitrogenous waste products break down into ammonia (NH3), which is highly toxic to most fishes. In nature, the volume of water per fish is extremely high, and waste products become diluted to low concentrations. In aquariums, however, it can take as little as a few hours for ammonia concentrations to reach toxic levels. How much ammonia is too much? The quick answer is: if a test kit is able to measure it, you’ve got too much (i.e., it’s in a high enough concentrations to stress fish). Consider emergency action (water changes and zeolite clay) to reduce the danger. (A more detailed discussion of ammonia toxicity can be found later in this section.) In aquaria-speak, the “nitrogen cycle” (more precisely, the nitrification cycle) is the biological process that converts ammonia into other, relatively harmless nitrogen compounds. Fortunately, several species of bacteria do this conversion for us.
Nitrogen is the major component of earth’s atmosphere. It enters the food chain by means of nitrogen-fixing bacteria and algae in the soil. This nitrogen which has been ‘fixed’ is now available for plants to absorb. These types of bacteria form a symbiotic relationship with legumes–these types of plants are very useful because the nitrogen fixation enriches the soil and acts as a ‘natural’ fertilizer. The nitrogen-fixing bacteria form nitrates out of the atmospheric nitrogen which can be taken up and dissolved in soil water by the roots of plants. Then, the nitrates are incorporated by the plants to form proteins, which can then be spread through the food chain. When organisms excrete wastes, nitrogen is released into the environment. Also, whenever an organism dies, decomposers break down the corpse into nitrogen in the form of ammonia. This nitrogen can then be used again by nitrifying bacteria to fix nitrogen for the plants. http://library.thinkquest.org/11353/nitrogen.
Like all living creatures, fish give off waste products (pee and poo). These nitrogenous waste products break down into ammonia (NH3), which is highly toxic to most fishes. In nature, the volume of water per fish is extremely high, and waste products become diluted to low concentrations. In aquariums, however, it can take as little as a few hours for ammonia concentrations to reach toxic levels. How much ammonia is too much? The quick answer is: if a test kit is able to measure it, you’ve got too much (i.e., it’s in a high enough concentrations to stress fish). Consider emergency action (water changes and zeolite clay) to reduce the danger. (A more detailed discussion of ammonia toxicity can be found later in this section.) In aquaria-speak, the “nitrogen cycle” (more precisely, the nitrification cycle) is the biological process that converts ammonia into other, relatively harmless nitrogen compounds. Fortunately, several species of bacteria do this conversion for us. Some species co
Page Description: In this science printable, students will interpret a diagram and correct false statements about the role of plants, animals, and bacteria in the nitrogen cycle. Grade Levels: 6 – 12 The full page is available ONLY to subscribers. Sign up today for a free 7-day trial to get access to this page and all of the 20,000 items on TeacherVision.
