Educational Model: The Sulfur 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 provides an understanding of sulfur movement during the corresponding biogeochemical cycle. The theoretical material related to the model is presented in the section Biogeochemical Sulfur Cycle in the manual "Ecology: Biology of Interactions." The scheme in the working area of the screen presents the main sulfur 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 sulfur within these pools. Rectangles indicate pools that cannot be directly correlated with the scale, because sulfur in them has different oxidation states. Arrows connecting the pools represent flows of transformation of sulfur atoms. You will be presented with a set of “cards” showing individual stages of sulfur 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. 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: 1. Place the proposed set of “cards” in the corresponding positions of the scheme. 2. Construct transformation pathways in which sulfur passes from oxidized to reduced form.