# 北美环境工程代写 | Air Pollution

ECI/ATM 149 Homework Assignment #1: Due Friday, 18 January 2019 by 3 pm

Updated: 1/11/2019 4:39 PM

All HW assignments for ECI/ATM 149 must be turned in to the course HW Box located on the 2 nd floor of Ghausi Hall. Remember that, as in every class you take at UCD, all incidents of plagiarism or cheating will be treated seriously and referred to student judicial affairs. You are required to adhere to the principles laid out in the UC Davis Academic Code of Conduct (http://sja.ucdavis.edu/cac.html). You must show your work in quantitative questions for full credit. If you’re work is not organized and legible it may not be graded.

50 points total

1. Briefly explain the difference between a primary pollutant and a secondary pollutant and provide at least one example of each (3 pts).

2. Regional Emissions: Calculate (i) the total number of grams of primary PM 2.5 emitted from passenger cars over the course of an entire year in kg‐PM 2.5 yr ‐1 , and (ii) the number of grams of primary PM 2.5 emitted on average per square meter per year (g‐PM 2.5 m ‐2 yr ‐1 ) in Yolo County from passenger automobiles. (This is termed an emissions flux.) (10 pts)

Given:

• Gasoline properties o Density = 0.72 g cm ‐3 o Carbon content = 0.842 g‐C (g‐fuel) ‐1 = 0.842 grams of carbon per gram of fuel Assume a fleet‐average fuel economy of 24.7 miles gal ‐1 and that all passenger autos operate on gasoline (as opposed to diesel) 1 EF PM2.5 = 0.05 g‐PM 2.5 /kg‐fuel. 2 Yolo county area is 1,024 sq miles.
• There are 121,083 registered autos in Yolo County.
• Assume the average number of miles traveled annually per vehicle is 14,435.
• Assume that Yolo people stay in Yolo (i.e. that all miles driven are in Yolo county).

3. Emissions: The density of “woody biomass” in the Sierra Nevada forests is variable, but a typical value is 100 Mg per hectare.  A typical emission factor of PM 2.5 from a forest fire is 13.1 g‐PM 2.5 per kg fuel. The Camp Fire burned 153,336 acres. 9 If it is assumed that 50% of the biomass was consumed by fire, calculate the total amount of PM 2.5 emitted to the atmosphere from the Camp Fire (in kg). Compare your answer for this one fire to the estimated total PM 2.5 emitted from light‐duty vehicles (aka passenger cars) for CA of 6.7 x 10 6 kg per year. 10 (6 pts)

4. Emissions: Reports from the 2015 VW diesel passenger vehicle scandal indicate that the vehicles emitted up to 35 times more NO x than the relevant US standard of 0.07 g mi ‐1 = 0.043 g km ‐1 in CA. 11 There have been 489,000 diesel passenger cars sold in the US since 2009. There are approximately 250 million cars on the road in the US. If you assume that all of these diesel passenger vehicles emitted exactly 35 times as much NO x as the US standard and that all other vehicles emitted at the standard limit, what would be the actual fleet average (aka weighted average) emission factor in g mi ‐1 ? You can assume that the diesel vehicles are a subset of the entire fleet. (6 pts)

5. Emissions: (a) Use the EPA website and database of the National Emissions Inventory to determine what fraction of total NO x emissions in the entire US in 2014 came from fuel combustion and what fraction came from mobile sources. 12 (b) What are the same fractions for California? (c) For CA, what are the fractions if fires are excluded as a source? (d) What types of sources does the “fuel combustion” category encompass? (9 pts total)

6. NAAQS: (a) How many criteria pollutants are currently regulated by the US EPA and what are they? (b) Use the EPA website to determine and report the largest source sector sub‐category for each of the criteria pollutants on a national level and for California. (Hint #1: As an example of a “source sector subcategory”, for CO on the national level the answer is “on‐road mobile,” being 37.09% of the total. Hint #2: for O 3 you can instead consider sources of volatile organic compounds, or VOCs.) (8 pts)

7. Based on the readings (see course schedule) and/or the links provided on Canvas (see the modules), identify at least one negative health impacts of exposure to O 3 , one negative effect of O 3 on ecosystems and one negative effect of exposure to PM 2.5 . (3 pts)

8. Emissions Sources: Provide an explanation as to why the primary sources of SO 2 and CO are so different (stationary vs. mobile) even though both come mainly from combustion of fossil fuels. (4 pts)

9. According to a recent study (summarized in an article available on Canvas here), outdoor air pollution contributes to 3.5 million premature deaths each year worldwide. What are the three main general sources identified, and list them in their order of importance (most‐to‐least). (Here “main source” refers to the broadest categories, and not the specific subcategories. So not, for example, “local waste disposal” but the broader source of which this is a subset.) (3 pts)

10. If the average carbon content of gasoline is 0.842 g‐C (g‐fuel) ‐1 (from Problem 1), what must be the average chemical formula of the hydrocarbons that make up gasoline if it is assumed that gasoline is entirely composed of non‐cyclic saturated hydrocarbons (i.e. molecules with generic formulas of C x H y )? (4 pts)

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