Name_______________________ Student I.D. ______________ EnvE320 Sample Final Examination

Name_______________________
Student I.D. ______________
EnvE320 Sample Final Examination
Attempt All Questions
Please fill in your answers (either √ if true, or X if false) to the brackets printed on the
right hand side of each problem.
(a) Specific heat of air at constant pressure (Cp) is bigger than the specific
heat of air at constant volume (Cv).
(b) Marine life will still mostly survive even if water contracts instead of
expands when it freezes.
1.5%/sub(c)
BOD is the amount of oxygen required by microorganisms to oxide
problem
wastes anaerobically.
(d) Lakes located in regions geologically dominated by limestone are
vulnerable to acidification.
(e) Among various greenhouse gases, CH4 contributes the most to global
warming because it is present in large quantity in the atmosphere.
(f) Even if without the greenhouse effect, life on earth will still be possible.
Pick only one answer (√) per sub-problem from each of the five choices
given below. Please note that simple calculations may be necessary to
determine the right answer.
(a) Which of the following materials can yield the most groundwater?
(i) Coarse gravel
(ii) Fine sand
(iii) Coarse sand
(iv) Dune sand
(v) Peat
2.5%/sub(b) Overall, which of the following pollutants impairs the water quality of
problem
lakes in North America the most?
(i) Pathogens
(ii) Oxygen-depleting substances
(iii) Nutrients
(iv) Heavy metals
(v) Thermal pollutants
(c) Which of the followings leads to a form of non-point source pollution?
(i) Pipes of industries
(ii) Wastewater treatment plants
(iii) Industrial flumes
(iv) Animal feedlots
(v) Domestic sewage
(d) Between the following water users, which user consumes the most and
returns the least amount of water back to the system?
(i) Agriculture
(ii) Power plants
(iii) Municipal
(iv) Industry
(v) Mines
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2.5%/subproblem
(e) Given that at 0oC and 1 atm pressure, 1 mole of ideal gas has 22.414
liters, what is the volume of ideal gas at 20oC in liters?
(i) 22.1
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(ii) 22.9
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(iv) 24.1
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(v) 25.2
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(f) Which of the following assumptions is not incorporated into Theis’
solution to solving unsteady flow of confined aquifers?
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(i) Homogeneous and isotropic
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(ii) Areally finite
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(iii) Aquifer is of uniform thickness
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(iv) Well is fully penetrating
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(v) Well loss is negligible
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(g) Given the surface temperature of Mars is 218oK, what is the wavelength
in μm at which Mar’s spectral radiance emitted is at the maximum?
(i)
0.5 μm
(ii)
1.5 μm
(iii) 5.2 μm
(iv)
10.1 μm
(v)
13.3 μm
(h) The energy content of coal is 24 KJ/gm, and has 62% of carbon, what is
the amount of CO2 emitted in g/MJ of energy released by burning coal?
(i)
5
(ii)
20
(iii) 50
(iv)
95
(v)
127
(i) Based on the analysis of Carnot engines, what is the highest efficiency
attainable (%) for an engine if the heat source has a temperature of
800oC, while the discharge has a temperature of 35oC?
(i)
31%
(ii)
51%
(iii) 71%
(iv)
81%
(v)
91%
(j) According to IPCC (2007), which of the following factors should
contribute most to the observed increase in globally averaged
temperatures since the mid-twentieth century?
(i) Decrease in sunspots numbers
(ii) Increase in solar radiation
(iii) Orbital variations of earth
(iv) Anthropogenic effects
(v) We are at the interglacial era of the climate cycle
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(k) Due to the planetary albedo of about 0.31, the amount of incoming solar
radiation reflected back to the outer space is:
(i) 57 Wm-2
(ii) 107 Wm-2
(iii) 157 Wm-2
(iv) 207 Wm-2
(v) 257 Wm-2
2.5%/subproblem (l) From the perspective of human perturbations to global carbon cycle
during the 1990s, given that the airborne fraction is only 38%, and the total
carbon emitted to the atmosphere due to fossil fuel, cement and land-use
changes is 8.5 GtC/year, what is the atmospheric net gain in GtC/year?
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(i) 2.1 GtC/yr
(ii) 2.8 GtC/yr
(iii) 3.2 GtC/yr
(iv) 3.9 GtC/yr
(v) 4.4 GtC/yr
(2)
(a) A black German shepherd of body surface area 1.5 m2, an average body
7%
temperature of 35oC, is out in an open environment at -5oC. Assuming this dog is
a perfect blackbody, find its heat loss by radiation in watts.
7%
7%
12%
(b) A BOD test is run using 100mL of treated wastewater mixed with 200mL of pure
water. The initial DO of the mix is 9 mg/L. After 5 days, the DO is 4 mg/L.
After a long period of time, the DO is 2 mg/L, and it no longer seems to be
dropping. Assuming nitrification has been inhibited so that the only BOD being
measured is carbonaceous, what is the BOD5 of the wastewater, and the reaction
rate constant k (day-1)?
(c) Given that the current nitrous oxide (N2O) concentration is 320 ppb, estimate the
total mass of N2O globally, given that the total mass of the atmosphere is about
5.12 x 1018 kg, & average air density is 1.2918 kg/m3.
(3) The Calgary City is located along a scenic stretch of the Bow River and the city is
seeking a waiver from the Alberta Government to permit it to discharge its treated
wasterwater into the Bow River. The regulators will give permission for the discharge if
Calgary can show that the minimum dissolved oxygen (DO) maintain a minimum level of
3 mg/L to ensure the survival of its fish population in the river. Given the following
wastewater quality information, estimate the minimum downstream DO (DOmin)
concentration in mg/L to determine whether or not Calgary have to upgrade its
wastewater treatment facility. First estimate tc, time to the critical point, and then DOmin.
Parameter
Waste water discharge rate (Qw)
Minimum river discharge (Qr)
DO content in the wastewater (DOw)
DO content in the upstream river (DOr)
DO saturation concentration at 20oC
BOD concentration of wastewater, BODw
BOD concentration in upstream river, BODr
BOD decay constant, kd
Re-aeration constant for the river, kr
12%
8%
8%
Quantity
5 m3/sec
100 m3/sec
0.3 mg/L
7 mg/L
9 mg/L
168 mg/L
0 mg/L
0.2 day-1
0.4 day-1
(4) Given the following time-drawdown curve recorded in an observation well located (r)
118m away from the test well operated at a pumping rate of Q = 0.008 m3/sec plotted on
the 3 x 5 log-log paper attached, the well function W(u) (overhead transparency)
provided, and Theis equation, estimate the transmissivity T (m2/day) and the storage
coefficient Sc, by matching the plots of W(u) versus 1/u, and s versus t, at some
convenient points for W(u) and 1/u. Mark on the W(u) overhead transparency and the
time-drawdown curve the matching points used to derive your answers. Be sure to hand
in both the W(u) overhead transparency and the time-drawdown curve. The timedrawdown curve has already been plotted on the log-log paper.
(5) (a) For most greenhouse gases, injection of 1 kg into the atmosphere decays
exponentially with time (but not CO2). What is the GWP of 100years for HFC-134a
100
Fg
given that
= 4129, τ = 14 yrs, and  RCO2 (t )dt  43.1 yrs ?
FCO2
0
(b) A lake with 100 x 106 m2 of surface area for which the only source of phosphorus is
the effluent from a wastewater treatment plant. The effluent flow rate is 0.4 m3/s, and its
phosphorus concentration is 10 mg/L. The lake is also fed by a stream having 20 m3/s of
flow with no phosphorus. If the phosphorus settling rate is about 10m/yr, estimate the
average phosphorus concentration in the lake. What level of phosphorus removal at the
treatment plant would be required to keep the average lake concentration below 0.010
mg/L?