Please show work/drawings of box models

1. Dead organic matter can be very crudely divided into two categories: labile (or "the fast pool") and recalcitrant (or "the slow pool"). Labile organic matter decomposes rapidly, while recalcitrant compounds are more resistant to decay. Consider the following model of the passage of organic carbon through the soil of the world's terrestrial ecosystems: a. What are the steady state stocks of carbon in the two pools? (5, 5 pts.) b. What is the residence time of soil carbon in the entire soil. (5 pts.) c. In reality, carbon atoms in soil organic matter in each of these conceptual pools are mixed together. If it were possible to track the transit times of all carbon atoms in the soil at any one time, with the shares in the labile and recalcitrant pools as above, what would be the average of these individual transit times? (5 pts.) d. Now, instead of calculating the average transit time for the carbon atoms in the soil organic matter at any given time, calculate the average transit time of all the carbon atoms entering the soil. ( 5 pts.) e. Which answer (c. or d.) is identical to your answer in b. above (what we call the soil carbon residence time)? The value calculated for d. is an average of transit times weighted by incoming flow, while that for c. is an average of transit times weighted by the equilibrium stock. Why do we usually want to know the flow-weighted average rather than the stockweighted average? Can you think of an environmental problem in which it would be useful to know the stock-weighted average? (9 pts.)