Educational Model: Energy Sources for Biogeochemical Cycles Using the Phosphorus Cycle as an Example
Working with the model makes it possible to identify the main stages of the phosphorus cycle, as well as the main energy sources both for this cycle and for the biogeochemical cycles of all substances.
Part of the IUMC (Innovative Educational and Methodological Complex) “Ecology: Constructing the Biosphere,” developed in 2008 by D. A. Shabanov, A. G. Kozlenko, and M. A. Kravchenko by order of the NTFP (National Training Foundation) of the Russian Federation (more about this project is in the article "Innovation and Reality"; the reasons why this complex is not used are briefly described in the column "Textbooks: Straight into the Day After Tomorrow"). This model is posted here for educational use. Working with the model makes it possible to identify the main stages of the phosphorus cycle, as well as the main energy sources both for it and for the biogeochemical cycles of all substances. The theoretical material related to the model is presented in the section Sources of Energy for Biogeochemical Cycles in the manual "Ecology: Biology of Interactions." At the first stage of the model, the working area of the screen shows a scheme of the global phosphorus cycle: pools of this element with flow-arrows connecting them. A dashed arrow shows the movement of sedimentary rocks formed on the ocean floor. Due to plate tectonics and other processes, they may rise above sea level and become involved again in the cycle of transformations. You will be presented with a set of “cards” showing individual stages of phosphorus transformation in the cycle. While completing the task, you need to place each card on the corresponding arrow in the scheme. To do this, select a card from the set by its number, find the arrow (flow) in the scheme corresponding to that card, and click this arrow with the cursor; the card number will appear in a circle on that arrow. At the second stage, you need to evaluate the significance of different processes supplying energy for the normal functioning of the phosphorus biogeochemical cycle (BGC cycle), and the consequences of excluding one of these processes. Pale arrows in the displayed animations indicate a substantial decrease in the intensity of the corresponding flows. Instructions for working with the model are located at the very bottom of its window; if these instructions do not fit in the box, they can be scrolled up and down using the arrows on the right. Some tasks that can be solved while working with the model: Stage I 1. Examine the scheme of the phosphorus biogeochemical cycle. Distribute the proposed set of “cards” to the corresponding places in the scheme. 2. Describe the differences in re-entry into the biogeochemical transformation cycle of sedimentary rocks formed in inland waters versus those formed in the ocean. Stage II 3. Using the phosphorus BGC cycle as an example, determine the outcomes of processes that supply energy for biogeochemical cycles. After observing specific disturbances of the phosphorus cycle, determine which energy-supplying process ceased to operate.