OCN400 - Problem Set #4 Jim MurrayAutumn 2001 (11/15/01)Carbonate Chemistry1) Assuming you know the following, solve for the concentration of CO32- in surfaceseawater by an online approach. Go the website at http://cdiac.esd.ornl.gov/ftp/co2sysand download the program co2sys.exe. To do this just follow the instructions given. Thiswill give you a state of the art program by Lewis and Wallace with Dept. of Energy(DOE) funding for performing CO2 system calculations. Do the calculations for questions1a and 1b using this program and compare the answers with what you got in Problem Set#3.When running the program it will ask you questions about your problem. To beconsistent, everyone in OCN421 should use when asked : single-input mode, Peng et alconstants, PCO2, the Dickson value for KSO4, and the NBS pH scale. Use S=35 , 25°Cand 0m.a) Assume Total CO2 = 2.0 x 10-3 mol kg-1. Determine the concentration ofCO32- at pH 8.0.. b) Assume total CO2 = 2.0 x 10-3 mol kg-1 in equilibrium with the atmosphere(PCO2 = 10-3.5) what is the CO32- concentration?2) How will fossil fuel CO2 change the pH of the ocean?Scientists project that PCO2 will eventually triple from its pre-industrial value of 280 ppmto at least 850 ppm. Assume alkalinity stays constant at 2.300 x 10-3 eq l-1.Assume K1’ = 10-6.0 and K2’ = 10-9.1a. What will be the initial (at 280ppm) and final (at 850ppm) pH for this model?d. What are the pros and cons regarding the asumption that the alkalinity stays constant?c. How would you set up the problem to solve for the pH assuming that CaCO3(s) was atequilibrium with seawater while PCO2 was increasing? Don't do any calculations here butsee if you write what equation(s) you would use.Box Models: Particulate carbon flux3) Using the box model you have worked on in the previous problem sets assume thefollowing values for total CO2 (e.g. C) and alkalinity (e.g. A) in the surface and deepocean. Assume Vmix = 300 cm y-1.Cs = 1932 µmol kg-1As = 2277 µmol kg-1Cd = 2256 µmol kg-1Ad = 2374 µmol kg-1a) Calculate the magnitude of the total carbon flux from the surface ocean (e.g. B) and thefraction of B preserved in sediments ( f ) for two cases:Case 1: neglect river inputCase 2: include river input with Cr = 960 µmol kg-1 and Vr = 4.6 x 1019 cm3 y-1.Explain if the answers make sense.b) Use an alkalinity balance for the surface box to calculate the relative contributions ofCaCO3 and organic C to the total carbon flux (B). Assume Ar = Cr. How does youranswer compare with the ratio of CaCO3 to organic C in deep ocean sediment trapsamples (see lecture notes)?c) If Vmix was 50% faster during the last glacial maximum, as has been proposed, whatwould be the new values of B and
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