CH217

Practice Exams and Homework calculations: O2 solubility and P flux HW, Great Pond P flux

Ch142 Final 2000, CH217 Final 2008

Homework:  (Due 4/7/2013)  Great Pond has an average depth of 6.4 meters, a surface area of 3452 ha and a shoreline length of 74.2 km.   The residence time of water in the lake is 2.3 years.  Assume the outflow of water over the Great Pond Storage Dam has a phosphorus concentration of 8 ppb (as P), and the inflow water (streams and rain) has phosphorus concentration of 4 ppb.   The average annual sediment flux of phosphorus is 5 milligrams (as P) per meter squared.   If the lake is 30% developed with an average shorefront lot length of 100 meters, what is the annual flux of P per lot?

If the average P in the lake has increased 0.3 ppb per decade for the last 50 years, what was the anthropogenic flux from each lot 50 years ago?

If the number of developed lots increases by 40% over the next two decades, what will be the new steady state P concentration in the lake in twenty years?  Assume the same anthropogenic P flux per lot as today.

Which of the assumptions in this problem is the worst?

Resources:   An Excellent Overview of Redox Chemistry,  CH217-Redox.1.2012,  Nutrient Data

Reading: Chapter 8.

Homework:  Due 4/30/2013

Consider a lake of infinite horizontal dimension, a depth of 20 meters, and a thermocline at 10 meters.  The epilimnetic temperature is 25 ^oC.    The hypolimnetic temperature is 6^oC.   Both layers are well mixed vertically.  The alkalinity of the lake is 0.10 mM.   The hypolimnion volume is 10% of the epilimnetic volume. Draw a sketch of the lake and use it to answer the questions below.

1) Calculate the equilibrium concentration of oxygen at depths of 5 and 15 meters in units of ppm and moles/liter.

2) Lakes in Maine tend to bloom when the dissolved phosphorus in the springtime is above 12 ppb (as P).   Assume that all of 12 ppb P is converted to biomass in the epilimnion.  What fraction of the epilimnetic biomass is required to reduce the oxygen in the deep water to below 1 ppm?

3) If bacterial oxidation of the deep biomass is complete, what is the phosphourus concentration in the deep water just before the fall overturn?

4) Qualitatively, will the pH of the deep water increase or decrease over the course of the summer?

Resources:  CH217-Geochem2-2012, Carbonate Constants 2012, Belgrade Lakes Project

Review for the second exam - CH217 Exam II 2010

Reading:   Chapter 8.

Homework:   We are beginning a series of homework assignments calculating the physical and chemical properties of water.   Please create ONE Workbook with multple worksheets, one for each assignment.  You will be able to use your workbook for the next exam.  This week you will create two worksheets.

1) Calculate the density of water as a function to temperature and salinity.   Plot the density as a function of temperature for four different salinities (0 to 35 o/oo).   At what salinity will cold water no longer have a density maximum?  Assume that you have two 1 meter cube blocks of water sitting on top of each other.   The top block is 25 0C and the bottom block is 15 oC.   How much mechanical energy would be required to move the bottom block to the surface?

2) Calculate the solubility of oxygen in mg/L and micro mole/L as a function of temperature and salinity.  Plot the solubility of oxygen as a function of temperature for four different salinities (3 to 35 o/00).

Hand in each worksheet printed on a single page of paper.  Due 4/23/2013 HW Key:  density of water

Resources:  CH217-Geochem1-2013 CH217O2 solubility, density of water, density at high salinity, test your equations (view source for the code), solubility of oxygen.

Reading:  Chapters 6 and 7 from the text.

Homework: 7: 24, 25, 27, 29, 30, 34  due 4/18/2013

Resources:  http://www.epa.gov/airtrends/index.html

http://www.dec.ny.gov/pubs/43763.html

http://www.epa.gov/region1/eco/acidrain/future.html

Second Exam: 4/25/2013

Reading: Chapter 3, IPCC Reports

Homework: 1) Calculate the average global temperature of the earth if it were 20% closer and 20% further away from the sun.   2) How would this average global temperature change with increasing CO2?  3) Why is the global warming potential of some gases many times higher than the GWP of CO2?  - due 4/9/2013.

Resources:  CH217 Climate Change 2012, Global Warming Potentials

Reading: Chapter 6  and  A.E. Perring, T.H. Bertram, D.K. Farmer, P.J. Wooldridge, J. Dibb, N.J. Blake, D.R. Blake, H.B. Singh, H. Fuelberg, G. Diskin, G. Sachse, R.C. Cohen, Alkyl nitrate production and persistence in the Mexico City Plume, Atmos. Chem. Phys. Discuss., 2009. [ Read the paper]

http://www.epa.gov/ord/htm/CAAA-2002-report-2col-rev-4.pdf

Homework:  Using the link (http://aura.gsfc.nasa.gov/science/feature-022207.html) as a starting point, sketch the concentrations of HNO3, HCl, CLO, and O3 in the Antarctic stratosphere during the winter of 2006.  On your figure list the most significant reactions that drive the observed concentrations.    What do you predict for the residence times of each of these species?   due – 3/21/2013

Resources:   spol_98low, Excellent Ozone Movies, EPA Ozone,  CH217-Smog-2012,  CH217 Acid Rain 2012

Reading: chapter 5

Homework: 5: 6, 9, 13, 16, 26, 34, 42, 49 – due 3/12/2013

Updated Hour Exam Date – 3/14/2013, Practice Exam:  CH217 First Exam 2012

biomass fuel Homework key, Quiz II key

Lecture:   CH217-L4.Atms1 2013

Homework: 2: 1, 4, 25, 27, 39   – Quiz 3/7/2013

Reading:

Chapter 2 and 4

Homework:  3: 1, 4, 25, 27, 39, 51  - Quiz 3/5

Resources:  CH217-L2.atmospere 2012

Reading:  Dark Energy, Chapter 1, 3

Homework: biomass fuel Homework - due 2/26/2013

Resources:  Alternative Fuels, Gus Libby Energy 2012, CH217-L1-big-bang-2012, atmosphere calks, Harvesting Biomass, Typical Heating Plant, Newspaper Article on Sustainable Harvesting