Educational Model: The Carbon Biogeochemical Cycle Under Present-Day Earth Conditions

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. The model makes it possible to identify the main stages of the carbon biogeochemical cycle. The theoretical material related to the model is presented in the section Biogeochemical Carbon Cycle in the manual "Ecology: Biology of Interactions." The scheme in the working area of the screen presents the main carbon pools, indicated by ovals and rectangles. Note that the position of pools in ovals corresponds to the oxidation-reduction scale located beneath the scheme. This makes it possible to determine the state of carbon within these pools. Rectangles indicate carbon pools in living organisms and detritus. They cannot be directly correlated with the scale, because carbon in them has different oxidation states. Arrows connecting the pools represent flows of transformation of carbon atoms. You will be presented with a set of “cards” showing individual stages of carbon 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 of work—after correctly completing the task with the “cards”—you will need to numerically evaluate the intensity of carbon 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 carbon biogeochemical cycle. Move the proposed 8 cards, which schematically show processes of carbon-atom transfer, to the corresponding arrows in the scheme. 2. Construct possible pathways of carbon-atom transfer from marine sedimentary rocks (limestone) into detritus. Pay attention to changes in the oxidation state of carbon atoms. Stage II 3. Examine the flow intensities labeled in the scheme for some stages of the cycle. The numbers near arrows indicate the amount of carbon moved along these pathways in millions of billions of grams (10^15 g) per year. Calculate the intensity of the flow next to the empty field. Enter the correct answer in this field from the keyboard, then click the “Check” button.