Week 8 LG 3.2.3 - Phosphorus Cycle PDF

Subject Code: IS 1 Integrated Science 1 Module Code: 3.0 Investigating the Biosphere II Lesson Code: 3.2.3 Phosphorus Cycle Time Frame:...

Subject Code: IS 1 Integrated Science 1 Module Code: 3.0 Investigating the Biosphere II Lesson Code: 3.2.3 Phosphorus Cycle Time Frame: 30 minutes TA ATA Component Tasks (min) (min) TARGET By the end of this learning guide module, the students should be able to: 1 1. Trace the path of the phosphorus cycle and how they affect living things. 2. Identify the general role of organisms in the phosphorus cycle. 3. Identify the chemical reactions involved in the phosphorus cycle. HOOK From the passage below, answer a short response question for this warmer 3 exercise: Different states of matter (solid, liquid, and gas) have different arrangements of atoms in it. The following figure illustrates this: Figure 1. The three states of matter are shown here. In solids, the particles are tightly squeezed together. In liquids, the particles can move more compared to solids. On the other hand, particles in gasses are spread out. Photo taken from (The University of Waikato Te Whare Wānanga o Waikato, 2007) Based on the first discussion on the introductory lesson of biogeochemical cycles we know that there are four geospheres or compartments that the elements travel during the cycle. These geospheres are composed of predominantly one state of matter. Unlike other nutrients, phosphorus exists as a liquid form in normal temperatures and pressures thus movement is dominantly in the three geospheres except the atmosphere (Lenntech B.V., 2020). Based on this information, describe how fast the movement of phosphorus on Earth: The lithosphere, biosphere, and hydrosphere are mostly solid and liquid matter. So given the atomic arrangement of solids and liquids, the movement of nutrients in these will be very slow compared to the other biogeochemical cycles. IGNITE Before we start, let us define some important concepts that we will discuss in 17 this lesson: Ions are atoms or a molecule that has an electric charge. It is usually written by using a superscript to the sign and magnitude of their charges (chemicool.com, 2017). PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Integrated Science 1 Page 1 of 7  Apatite is a group of phosphate minerals and is an important component of phosphorite (rock mined for its phosphorus content) (King, n.d.). DNA, or deoxyribonucleic acid, is a blueprint material of almost all living organisms. In a person's body, every cell has an identical DNA (National Human Genome Research Institute, 2020). Organic compounds are mainly coming from organic organisms that contain carbon while inorganic compounds are obtained from natural processes and man-made processes (chemical manufacturing of fertilizers) and do not contain carbon (with some exceptions) (BYJU’S, n.d.). A limiting nutrient is when an element/compound (phosphorus for example) is in limited supply, thus controlling the rate of growth of organisms. This is particularly true for aquatic and freshwater ecosystems (Khan Academy, n.d.). Plants are the primary producer in the phosphorus cycle where it is concentrated in its tissues. Sources of Phosphorus in the Geospheres If you answered our hook activity above with the phosphorus cycle being slow then you are correct! Unlike the previous elements (carbon, oxygen, and nitrogen), phosphorus does not exist in our atmosphere. The gases in our atmosphere are freely moving faster than the liquid and gas state. Phosphorus (represented by P in the periodic table of elements) in gas form can never be found in the natural environment in large amounts (Jahnke, 2019). These are naturally occurring in nature as phosphates and represented as an ion with chemical symbol PO4-3. It can be found naturally as apatite minerals. All these compounds coming naturally occurring processes are called inorganic forms of phosphorus. Figure 2. Two apatite fragments. Photo taken from (Pallardy, n.d.) Apatite is also being generated by living organisms as components of bodies like teeth, bones, and scales. After the mentioned organisms die, these elements usually accumulate in sediments and soils. Since all the organisms here on Earth are carbon-based life, these forms of phosphorus contain carbon and are called organic forms of phosphorus. Phosphate is an essential constituent of nucleic acids, DNA (material for the double helix), and RNA. Furthermore, it plays an important role also in the manipulation of chemical energy in cells via the processing of bonds of PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Integrated Science 1 Page 2 of 7  adenosine triphosphate (ATP). Lastly, phosphate is an important component of phospholipids, which are needed in the development of cell membranes and structural body parts of the organism. All of this plays a role in the chemical processes in the biosphere and without phosphorus, organisms cannot exist. The major inorganic source of phosphorus in sediments. Phosphates originate usually in igneous, metamorphic, and sedimentary rocks (Reservoirs - The Phosphorus Cycle, n.d.). This makes phosphorus unavailable to plants since it is locked up in sediments and rocks. The Phosphorus Cycle Like carbon-oxygen and nitrogen-cycles, the phosphorus cycle involves both the biotic and abiotic components. The rate of movement of phosphate is fast in the biosphere (plants and animals) but moves very slowly in the lithosphere (rocks and soil). The cycle starts when phosphate is weathered from rocks and minerals and is carried by gravity or rain to the terrestrial environment. These inorganic phosphates reach the soil and water. Vegetation (plants) absorbs these inorganic phosphates from the soil and then is eaten by animals. Once the animal or plant ingests these phosphates, it is then incorporated into organic molecules such as DNA (Science Learning Hub – Pokapū Akoranga Pūtaiao, 2013). Figure 3. The Phosphorus Cycle Photo taken from (Science Learning Hub – Pokapū Akoranga Pūtaiao, 2013) These animals and plants die as they reach the end of their lifespan. The process of decomposition helps return these organic phosphates to the soil. These organic phosphates are converted back to the inorganic form of phosphorus with the help of bacteria. This process is called mineralization. The phosphorus added in the soil can be transported to oceans or other bodies of water. After some time, these can be deposited into sediments. This soil level phosphorus cycle can be illustrated below: PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Integrated Science 1 Page 3 of 7  Figure 4. Soil-level Phosphorus Cycle Photo taken from (University of Hawai‘i - College of Tropical Agriculture and Human Resources, n.d.) Compared to other biogeochemical cycles the phosphorus cycle is not “perfect”. Instead of returning much of the element to the soil, it ends up in the bottom of bodies of water as runoffs. It takes millions of years for the bottom of the ocean to rise. This is the reason why farmers need to buy fertilizers containing phosphorus to be used in their crops. Chemical Reactions during Transformation in Soil When phosphorus enters the soils via inorganic sources and organic sources, it cycles in the soil through these different processes: Mineralization and Immobilization – When microbes convert organic phosphorus to inorganic phosphorus this is called mineralization. The reverse of this is called immobilization. During immobilization, microorganisms convert inorganic forms to organic phosphate, which are then absorbed by living cells (University of Hawai‘i - College of Tropical Agriculture and Human Resources, n.d.) Adsorption and Desorption – For the Phosphorus in the soil solution to attach to the surface of soil particles a process called adsorption needs to take place. It is a fast and reversible process wherein adsorbed phosphorus can be returned to the soil solution via desorption. Weathering, Precipitation, and Dissolution – Minerals break down over time in a process called weathering. It is a very long process of breaking down apatite to release phosphorus to the environment. On the other hand, precipitation of phosphorus involved reacting with another substance to form a solid. A specific form of weathering is called dissolution. This occurs when phosphate minerals dissolve and return phosphate to the soil solution (Prasad & Chakraborty, 2019). PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Integrated Science 1 Page 4 of 7  Maintaining the Balance in the Phosphorus Cycle Cycling of phosphorus in the three geospheres must be balanced, meaning that the number of nutrients overall in these compartments should be in a healthy balance. Phosphorous, together with nitrogen, is a limiting nutrient. To replenish the lacking phosphorus in the soil, farmers need to put in commercial fertilizers to supply nutrients to their crops. Sometimes over-fertilizing fields can cause leaching of phosphorus to bodies of water. This can cause an imbalance in the cycle and lead to disastrous consequences. For more on the human impacts of this imbalance, further discussion will be done in the succeeding lessons. NAVIGATE Let us test our understanding of this chapter by answering the following 6 questions. You can do this in a below, in a separate piece of paper or on your laptop. 1. Why is phosphorus a very important element in an organism’s biological activity? Phosphorus present in phosphates is an essential constituent of the double helix of our DNA. It is also important for the processing energy in our cells in the form of ATP. Lastly, it is needed in the development of cell membranes and structural body parts of organisms. 2. How are phosphates combined into the organic molecules in plants and animals? Through the process of absorption and immobilization, the organic phosphates are taken up by plants from water and are stored in plant tissues and are consumed by animals.__________ What is the difference of the phosphorus cycle to the other cycles mentioned before? _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ The atmosphere is not involved. PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Integrated Science 1 Page 5 of 7  3. Place the word fast in the blanks where the phase of the phosphorus cycle is fast and put slow where the phase is slow. Photo taken from (Beth, n.d.) KNOT To summarize the lesson: 3 The phosphorus cycle is different from the other biogeochemical cycle because it is not in large amounts in the atmosphere. Phosphorus exists naturally as phosphates. The phosphorus present in this mineral is hard to break down thus the process of weathering takes a long time. Phosphorus is very important in the biosphere as it is the main ingredient in the development and function of cells. Phosphorus is a limiting nutrient, especially in aquatic systems. Phosphorus present in soils cannot be used entirely by plants. It needs to be converted to a usable form. This is then returned to the soil and converted to inorganic form. PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Integrated Science 1 Page 6 of 7 References Beth, K. (n.d.). Simple Phosphorus Cycle Diagram | Carbon cycle, Cycle, Microbiology. Retrieved August 6, 2020, from https://www.pinterest.ph/pin/364087951102755737/ BYJU’S. (n.d.). Difference Between Organic and Inorganic Compounds Key Differences. Retrieved August 3, 2020, from https://byjus.com/chemistry/difference-between-organic-and-inorganic- compounds/ chemicool.com. (2017). Definition of ion - Chemistry Dictionary. https://www.chemicool.com/definition/ion.html Jahnke, R. A. (2019). Occurrence of Phosphorus. In Earth System Science Froom Biogeochemical Cycles to Global Change (pp. 316–376). Elsevier Academic Press. https://doi.org/10.1002/9781118786352.wbieg1087.pub2 Khan Academy. (n.d.). The phosphorus cycle. Retrieved April 24, 2019, from https://www.khanacademy.org/science/biology/ecology/biogeochemical-cycles/a/the- phosphorous-cycle King, H. M. (n.d.). Apatite: Its uses as a mineral and gemstone. 2005. Retrieved August 2, 2020, from https://geology.com/minerals/apatite.shtml Lenntech B.V. (2020). Phosphorus cycle. https://www.lenntech.com/phosphorus-cycle.htm National Human Genome Research Institute. (2020). What is DNA? - Genetics Home Reference - NIH. https://ghr.nlm.nih.gov/primer/basics/dna Pallardy, R. (n.d.). Apatite. Encyclopædia Britannica, Inc. Retrieved August 3, 2020, from https://www.britannica.com/science/apatite Prasad, R., & Chakraborty, D. (2019). Phosphorus Basics: Understanding Phosphorus Forms and Their Cycling in the Soil - Alabama Cooperative Extension System. https://www.aces.edu/blog/topics/crop-production/understanding-phosphorus-forms-and-their- cycling-in-the-soil/?cn-reloaded=1 Reservoirs - The Phosphorus Cycle. (n.d.). Retrieved August 3, 2020, from http://phosphoruscycles.weebly.com/reservoirs.html Science Learning Hub – Pokapū Akoranga Pūtaiao. (2013). The Phosphorus Cycle. https://www.sciencelearn.org.nz/resources/961-the-phosphorus-cycle The University of Waikato Te Whare Wānanga o Waikato. (2007). States of matter — Science Learning Hub. https://www.sciencelearn.org.nz/resources/1499-states-of-matter University of Hawai‘i - College of Tropical Agriculture and Human Resources. (n.d.). Soil Management. Retrieved August 6, 2020, from https://www.ctahr.hawaii.edu/mauisoil/c_nutrients02.aspx Prepared by Reviewed by Reviewed and approved by LUIS JULIUS G. BRAGAIS SUZETTE A. PALICTE ALICE C. MANUEL Special Science Teacher I Special Science Teacher IV Special Science Teacher IV Bicol Region Campus Southern Mindanao Campus Cagayan Valley Campus PHILIPPINE SCIENCE HIGH SCHOOL SYSTEM Integrated Science 1 Page 7 of 7