2005 solution

2005 solution - ER 102 Spring, 2005 J. Harte Solutions to...

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ER 102 J. Harte Spring, 2005 Solutions to Midterm 1. Taking the human population today to be 6.3 x 10 9 , and the mass of a typical person (very rough average over men, women, children) of 50 kg, we get a total mass of humanity of 3.15 x 10 11 kg. What is the mass of a typical ant. The ants that swarm in my kitchen on rainy days are about a mm in diameter and about 0.5 cm long. Hence their volume is 0.005 cm 3 . Assuming their density is that of water, they have a mass of 0.005 grams. Recognizing that many tropical ants are bigger than Berkeley ants, I will use an average ant mass of 0.01 grams = 10 -5 kg. . Any value between 0.1 and 0.001 was given full credit and only a few points were taken off for outrageously oversized ants. Hence I get 3.15 x 10 11 / 10 -5 ~ 3 x 10 16 ants. 2. i. Denitrification. Donor pool is nitrate; receptor is inorganic N in atmosphere. The rate of denitrification is donor controlled and also controlled by microorganisms. ii. Microbial immobilization. Donor pool is ammonium, and to a lesser extent nitrate, in soil; receptor pool is microorganisms. Rate is both donor and receptor controlled. iii. Plant assimiliation. Donor pool is soil inorganic N, receptor is plants. Rate is both donor and receptor controlled. iv. Nitrification. Donor pool is ammonium in soil; receptor is nitrate. Rate is donor controlled and also microorganism controlled. v. N-mineralization. Donor pool is organic N in soil; receptor is ammonium in soil. Rate is Donor controlled and also controlled by microorganisms. vi. Animal death. Donor is animals; receptor is organic N in soil. Rate is donor controlled. vii.
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2005 solution - ER 102 Spring, 2005 J. Harte Solutions to...

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