Did you know that all elements are recycled over and over again on Earth? In this lesson, we’ll learn about the biogeochemical cycle and explore the cycle of phosphorus as an example. Test your new knowledge at the end with a quiz.
Definition of Biogeochemical Cycle
Have you wondered what living organisms are made of? The building blocks that make up organisms include elements such as hydrogen, oxygen, carbon, nitrogen, phosphorus, and sulfur. Elements are the key ingredients that make up cells, DNA, proteins, hair, and skin.
If you were to break apart the human body you would find it is comprised mostly of the element oxygen.A biogeochemical cycle is defined as the movement of elements, like those mentioned just a moment ago, through organisms and the environment. A way to remember this is to break apart the word ‘biogeochemical’ into pieces. The first part of the word, bio, involves biological organisms, like bacteria, plants, and animals. The next part of the word, geo, involves geological processes, like weathering of rocks.
The last part of the word indicates chemical processes, such as the formation of molecules.
The Currency of the Earth
In society, people earn money in order to get some desired item like food or gas for their car. When you earn a paycheck, let’s say you go to the grocery store and buy some food. This money you spend then pays an employee for her hard work. The employee then uses this money to buy some food for her family. This money cycles over and over and is not lost.You can think of elements like carbon, nitrogen, phosphorus, and potassium as the currency of all ecosystems on Earth.
There is only so much available; it keeps circulating from one organism to another; and every organism is working hard to gather it so they can use it for a desired result. In the case of a living organism, this desired result might be the growth or strengthening of a certain part of the organism.
Nature Recycles Phosphorous
Not all elements have the same biogeochemical cycle. Some biogeochemical cycles are simple, while others are quite complex. Let’s take a look at the simple biogeochemical cycle phosphorus takes.
Phosphorus is trapped in sedimentary rocks. When exposed to water, phosphorus can be released in the form of phosphate ions. When phosphate ions wash away, they soak into the soil. Plants are starving for phosphate, so their roots gobble it up and incorporate it into their tissues.When an animal eats the plant, the phosphate transfers to the animal’s tissue. When the animal dies, decomposing bacteria cycle the phosphate back into the soil.
The phosphate can either be gobbled up by plants again or stay in the soil. If the soil conditions are right, any phosphate remaining in the soil can slowly reform back into rocks. You help recycle phosphorus, too! For example, a plant like spinach is full of elements like phosphorus. When you eat it, your body incorporates this element to form strong bones and teeth.
Human activities can impact the biogeochemical cycle of many elements.
One example is the mining of phosphorus, which is used to manufacture synthetic fertilizers for crops. When fertilizers are applied to land, some of them can wash into waterways. This application of fertilizers can actually speed up the phosphorus cycle. Too much phosphorus can deplete oxygen from the water, causing the death of large numbers of fish.
Elements cycle through a complex process involving living biological organisms, geological processes, and chemical processes.
This is known as a biogeochemical cycle. One example of a biogeochemical cycle that we looked at is that of phosphorus. Phosphorus is trapped inside sedimentary rocks. If these rocks are exposed to water, phosphate ions can wash away and soak into the soil. Phosphate is then available for plants and can move through the food chain to animals. It can be cycled back into the soil by decomposing bacteria.
You are part of the phosphorus cycle, too! When you eat plants, like spinach, you utilize phosphorus and incorporate it into your body. Humans have sped up the phosphorous cycle by using fertilizers, which run off into the waterways and kill fish.
Biogeochemical Cycle Definition & Example
- Biogeochemical cycle: the movement of elements through organisms and the environment
- The Biogeochemical Cycle of Phosphorous
- 1. Trapped in sedimentary rocks
When exposed to water, phosphate ions release
- 3. Phosphate ions soak into the soil
- 4. Plants utilize the phosphate in the soil to build plant tissue
- 5. Animals eat plants and the phosphate helps build animal tissue
- 6. Animals die and bacteria returns the phosphate to the soil
When this lesson is over, students should feel ready to:
- Define biogeochemical cycle
- Illustrate an example of a biogeochemical cycle
- Discuss the impact of humans on biogeochemical cycles