Detroit Architecture, the saxophone and Geochemistry

I’ll start with the good things:
I went to a meeting last week in downtown Detroit. Right smack downtown. In the Buhl building, for those of you who know Detroit. Across from the Buhl Building is the Guardian Building.

view inside:


view when you walk in the main doors:

I love this building. I love walking through the doors and having my breath taken away by the grandeur and beauty of the whole place.



Anyways - So, after enjoying myself in the Detroit that I love, I went to my meeting across the street. As I was walking across Griswold Street, there was a guy, playing saxophone on the corner. He was playing quite well - good jazzy tunes, some classic favorites, some R&B tunes. If I had walked right by him, I probably would have put a dollar in his case.


So, I continue to the 3rd floor for my meeting...and throughout most of the meeting...



we. still. heard. him.




How cool is that? right? I felt urban. I felt sophisticated. Here I was, discussing the future spending of the Great Lake Restoration Initiative Stimulus dollars, and how we could work for future growth...and I'm humming along to a version of "Endless Love". Nice...

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And the other thing I wanted to share with you...my geochem homework...

Show all work. Circle, underline, or box your final numeric answer.
1. Water is supplied to the atmosphere by evaporation from the surface and is removed by precipitation. The total mass of water in the atmosphere is 1.3 x 1016 kg, and the global mean rate of precipitation to the Earth’s surface is 0.2 cm/day. Calculate the residence time of water in the atmosphere.
2. Draw a multibox model of the sources of nitrate to surface waters. Use the nitrate sources provided in class. At a minimum, include boxes for the atmosphere, hydrosphere, biosphere, soils, and lithosphere. You may need 1-2 additional boxes, depending on how you classify sources.
3. A pond (1000 m3) sits above a mine tailings pile which contains PbCO3. A stream with no Pb2+ present in its waters enters the pond with a flow rate of 3500 m3/day. The PbCO3 in the tailings pile dissolves with a rate of kA(Cs – C), where k (0.2 /m2day) is the rate constant, A (1 m2) is the surface area of PbCO3 exposed to the pond waters, and Cs (15 mol/m3) is the saturation concentration of PbCO3. A stream exiting the pond has a flow rate of 3500 m3/day.
a.) Draw a simple one-box model for this scenario.
b.) Calculate the steady-state concentration (C) of Pb2+ in the pond.
c.) How does this concentration compare with the saturation concentration? Is the pond water saturated with Pb2+?
d.) Calculate the residence time of Pb2+ in the pond.
FYI: Recall that for any chemical mass balance, Mass = Volume × Concentration. The general steady-state equation we’ve talked about in class, dm/dt (change in mass with respect to time) = sum of sources – sum of losses, has units of mass/time (mol/day; kg/hour; etc.). As you set up a steady-state equation for this scenario, you’ll need to make sure the units on both sides of the equation are equal.

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Just in case you were wondering....