OCN421 – Problem Set #3 Jim MurrayAutumn 20011. During a recent cruise to the equatorial Pacific (at 0°, 140 °W in September 1992)new production was measured, using the NO3 uptake technique, to be 2.89 mmol Nm-2 d-1 while particulate organic carbon export was measured using drifting sedimenttraps to be 10.0 mmol C m-2 d-1.a. Were new and particulate export fluxes in balance on a carbon basis? AssumeRedfield ratios hold for uptake and particulate export material.b. If not, what might be the explanation?2. Use Broecker’s two-box model (e.g. see lecture chapter 10) and the concentrationslisted below to answer the following questions.Mean river and ocean concentrations in moles m-3.Constituent CriverCsurfCdeepP 0.0013 0.02 x 10-30.0023NO30.030 0.03 x 10-30.030DIC 1.2 1.95 2.30Ca 0.36 10.20 10.30a. Calculate the particulate carbon flux to the deep sea. Compare this value tothe fossil fuel CO2 production rate of 5.4 Gt yr-1 (5.4 x 1015 g yr-1). Whatfraction of the carbon in the particulate carbon flux originates from rivers?b. Calculate the P:N:C:Ca ratio of the particulate matter leaving the surfaceocean. How does you value compare with that of Broecker and Peng (1982)?[Lecture Chapter 8, Table 8-5; P:N:C:Ca = 1:15:131:26]c. If surface seawater oxygen concentration is equal to the value at saturationwith the atmosphere at a temperature of 0 °C and seawater salinity of 35,which is 3.5 x 10-4 moles kg-1, predict the oxygen concentration of the deepocean layer. What is the AOU? Compare the result with observations.3. You have measured O2 concentrations in the surface ocean over the course of a monthduring the summer. Average temperature and salinity were 25 °C and 35,respectively, for the period of observation. Average O2 concentration was 240µmoles kg-1. The concentration appeared to be at steady state.a. Draw a box-model for the mass balance of O2 in the surface layer. Indicatethe primary sources and sinks. Assume that vertical mixing processes werenegligible during the period of your study. Be sure to include gas exchange,bubble injection and biological production in your model.b. Calculate the air-sea gas exchange using the stagnant boundary layer model.Assume that DO2 = 1.7 x 10-5 cm2s-1 and z (the stagnant boundary layerthickness) = 30 µm. The saturation concentration of O2 for the conditions ofyour study is 220 µmoles kg-1.c. Determine the magnitude of the biological oxygen signal, assuming thatbubble input was negligible.d. What is the equivalent carbon production in molC m-2 yr-1 based on thisbiological oxygen signal (assume that 1 kg ~ 1 L)? How does it compare tototal primary productivity estimates in the world’s oceans? New primaryproductivity? Which of these fluxes should your estimates agree with andwhy?4. Assuming you know the value of total CO2 and pH in surface seawater, solve for theconcentration of CO32- by two approaches.a. Draw a distribution diagram on graph paper for the carbonate species inseawater for Total CO2 = 2.0 x 10-3 mol kg-1. Use apparent seawaterconstants (e.g. K’) from Chapter 12. Label the lines for H2CO3, HCO3-,CO32-, H+ and OH-. Determine from the graph the concentration of CO32- atpH 8.0.b. Derive an algebraic equation to solve for the concentration of CO32- fromknowing the Total CO2 and pH. Solve the concentration of CO32- for TotalCO2 = 2.0 x 10-3 mol kg-1 and pH =