ENSC 10143 Fall 2022 Study Set 2

What is non attainment?

They do not meet the National Ambient Air Quality Standards (NAAQs)

What are the two types of pollutants? Know how they form and some examples

Primary pollutants - emitted directly into the air. Can come from point sources such as industrial stacks (stationery) or non point sources such as cars (they move) - Secondary pollutatns form in the atmosphere through chemical reactions of primary pollutants, usually involving sunlight. For example, ground level ozone forms when oxides of nitrogen and volatile organic compounds (VOCs) react with sunlight to form O3

What is a point source? A non point source?

point sources such as industrial stacks (stationery) or non point sources such as cars (they move)

What are NAAQS and why do we have them?

Clean air act (1970) requires EPA to set National Ambient Air Quality Standards (NAAQS) for pollutants considered harmful to health and environment

What are the two types of standards (primary and secondary) and how are they different?

primary standards set limits on pollutants in order to protect public health - Secondary standards - public welfare (visibility, crop damage)

What are the 6 pollutants that we have NAAQS for?

There are 6 common air pollutants of concern called principal or criteria pollutants. Nitrogen oxides (NOx)- group of highly reactive gases that contain N and O in varying amounts. Form when fuel burnt at high T. Most colourless though No2 can be seen as reddish brown layer over cities. Nox one of main ingredients in forming ozone and acid rain Sulphur dioxide - formed when fuel containing sulfur is burned (coal). Dissolve in water to form acid. Power plants biggest contributor. SO2 also reacts with chemicals in air to form tiny sulfate particles = fine particle pollution - EPA says this causes 20,000 premature deaths a year Lead - metals manufacturing now major source of lead emissions now petrol is unleaded Particulate matter - small particles and liquid droplets. Can be ash, soil, dust. Impact to health linked to size - 10microns or smaller and they can enter lungs and blood stream CO - formed when C in fuel incompletely burned. Primary component of vehicle emissions. Can also come from industry and forest fires. Ozone - most problematic pollutant in usa for air quality.

What are the differences between the way some NAAQS are measured?

The time period they are measured over

What happens when NAAQs change?

Whenever standards are changed it can cost industry a lot to meet new standards and many areas can fall into non attainment

What are some of the penalties for non attainment?

Penalties for those that do not meet attainment such as suspending federally supported highway and transportation projects

Be able to describe all of the 6 main pollutants, where they come from, what they cause.

Nitrogen oxides (NOx)- group of highly reactive gases that contain N and O in varying amounts. Form when fuel burnt at high T. Most colourless though No2 can be seen as reddish brown layer over cities. Nox one of main ingredients in forming ozone and acid rain
Sulphur dioxide - formed when fuel containing sulfur is burned (coal). Dissolve in water to form acid. Power plants biggest contributor. SO2 also reacts with chemicals in air to form tiny sulfate particles = fine particle pollution - EPA says this causes 20,000 premature deaths a year
Lead - metals manufacturing now major source of lead emissions now petrol is unleaded
Particulate matter - small particles and liquid droplets. Can be ash, soil, dust. Impact to health linked to size - 10microns or smaller and they can enter lungs and blood stream
CO - formed when C in fuel incompletely burned. Primary component of vehicle emissions. Can also come from industry and forest fires.
Ozone - most problematic pollutant in usa for air quality. Is a secondary pollutant. Ozone formation is complex but most happens when NO2 and VOCS react with sunlight. NO2 and VOCs are called ozone precursors - they have to be emitted first.

Where is ozone found?

Both in the troposphere (pollutant) and in the stratosphere (not a pollutant, but actually protects us)

Why is ozone a pollutant?

Primary constituent of smog, dangerous to public health, can damage plants too as they respire

How does ozone form?

Ozone formation is complex but most happens when NO2 and VOCS react with sunlight.

What negative effects does ozone have?

Breathing is harmful at dosage levels of a few molecules per million air molecules. Doesn't just impact health (respiratory), also responsible for ecosystem damage - 500 million in reduced crop population. Ozone damages plants by entering leaf openings called stomata and oxidizing (burning) plant tissue during respiration. This damages the plant leaves and causes reduced survival.

What is the AQI?

Each day, the EPA monitors and records concentrations of the major pollutants (ground-level ozone, particle pollution at more than a thousand locations across the country = Air Quality Index Instead of reporting these values to the public in terms of the National Standards the measurements are converted into a separate AQI value for each pollutant which really simplifies the process. Scale of 1-500 where 100 is the federal standard, which is why colour changes to much more warm at that level Above 100 = unhealthy for sensitive groups and as it rises, more groups will be impacted

How is AQI represented?

Color coded chart

What can cause pollutants to be concentrated in certain areas?

geography and meteorology. For example, pollutants may become concentrated in lower lying areas, such as a basin and weather patterns can cause pollutants to be concentrated in areas other than the ones they form in.

How does an inversion form?

Inversions = meteorological phenomena that act like a lid keeping pollutants sitting over central valley communities. Air in contact with ground cools and drains down slopes to collect in low lying basins

Why is CA so polluted?

Unique geography and meteorology causing inversion

How has air quality changed in the last 30 years?

It has gotten better

Which pollutant is the most problematic?

Ozone

Why has there been a decrease?

Control measures thanks to the Clean Air Act: legislation, scrubbers in coal plants, and catalytic converters

How many people/percentage of the population live where pollution values are too high?

approximately 79 million people in USA nationwide (or 23% of the population) live in counties with pollution levels above the NAAQS for ozone. Recent analysis by the World Health Organization (WHO) found that 90% of the global urban population (based on 1,600 cities) are exposed to unsafe air pollution.

How has COVID impacted air pollution?

It got better

How much of the world population live in places where air quality is unhealthy?

Recent analysis by the World Health Organization (WHO) found that 90% of the global urban population (based on 1,600 cities) are exposed to unsafe air pollution.

Which country has the worst problem with air pollution?

India

How bad is New Delhi's air relative to the worst US city?

Three times higher for PM2.5

Why is the air pollution so bad in India?

the fifth most populous city in the world India has seen rapid development in the past two decades, but it has come at the cost of increasing pollution Weak industrial regulation means that factories generally do not follow pollution-control measures. Fine particulates are the biggest problem from coal burning, diesel engines, open fires, and farms using slash and burn agriculture

How many people a year does air pollution kill?

WHO estimates that dirty air kills around 7 million people each year

What is the world's largest environmental health threat?

Air pollution

Which of the NAAQs is considered the most harmful to human health and why?

PM2.5

How does acid deposition occur? What are the two types?

Primarily from the transformation of SO2 and NOx into secondary pollutants such as sulfuric acid (H2SO4) and nitric acid (HNO3). Deposited by: Wet deposition (acid rain) Dry deposition (SOx and NOx particles which are then washed away by rainstorms)

What is pH?

Concentration of H ions (H+)

Understand the pH scale (not linear, which pH is acid etc)

The lower the pH the more acidic it is, higher the more alkaline or basic This is not a linear scale, it is logarithmic so each whole pH number is a difference of 7-10 times more acidic pH 4 ten times more acidic than 5 and 100 times more than 6

What are the results of acid rain and dry deposition?

Acidify surface waters and soil. Damage the surfaces of leaves and needles, reduce a tree's ability to withstand cold, and inhibit plant germination and reproduction. Consequently, tree vitality and regenerative capability are reduced. Aquatic animals (from plankton to fish) are impacted - if it gets too acidic the female cannot spawn, or if she does the eggs do not hatch. Can damage buildings

Where in the USA is there a greater acidification problem and why?

In USA rainfall is most acidic in NE (caused by large number of cities, concentration of power and industrial plants)

What are the effects of acidification on bodies of water? Why?

Aquatic animals (from plankton to fish) are impacted - if it gets too acidic the female cannot spawn, or if she does the eggs do not hatch.

What are the effects of acid rain on forests/soils? Why?

It increases the concentration of aluminum in the soil which interferes with the uptake of nutrients by the trees. Lack of nutrients causes trees to grow more slowly or stop growing altogether. The more visible damage, such as defoliation, may show up later. Trees exposed to acid rain may also have more difficulty withstanding other stresses, such as drought, disease, insect pests, and cold weather.

How are some countries combatting the acidification?

they lime the lakes and soil to help increase buffering capacity but this is expensive. Lime acts like a filter in the upper layer of the forest soil, where it can capture and neutralize future acid deposition. The effect of the added lime penetrates slowly into the soil and persists for a long time in the future. Therefore, the liming of soil can help counter the acidification of surface water in the long term. If added to lakes it can also prevent them from becoming acidifed.

What is the difference between tropospheric and stratospheric ozone?

In previous lectures we discussed low level ozone aka tropospheric ozone, which is a low-level human formed pollutant. Formed as a secondary pollutant from primary air pollutants due to reactions with sunlight.

Know what and where the troposphere and stratosphere are.

Troposphere - closest to earth's surface, stratosphere - above troposphere

What is the ozone layer?

The ozone layer, or stratospheric ozone, contains about 90% of all atmospheric ozone

Why is the ozone layer important?

acts as the primary radiation shield for the earth's surface

Why is UV radiation a problem?

UV radiation is destructive to genetic cellular material in all organisms so it is biologically harmful if let through - so both ozones are concerning to us but in different ways

What exactly is the ozone layer? Know the facts about it (where its maximum is, where it is located in altitude)

While we call it a layer, that is a somewhat confusing term as it is dispersed over 20km of altitude. Even at its highest pressure it is 30 milliPascals. Air pressure at sea level is over 100 million millipascals. O and N are far more abundant. It's max is between 20—25 km. Know the figure on slide 4!

How does ozone form?

Ozone is formed naturally in the middle to upper stratosphere of the tropics. - Sun provides enough extreme ultraviolet radiation (EUV) to split O2 into 2 separate atoms, this is called photolyzed - Then the O atoms undergo a binding collision with O2 to form ozone

What is photolyzation?

splitting two bonded atoms apart, e.g. O2 to O and O

What does ozone do?

spends most of its life absorbing UV radiation. - The ozone molecule absorbs UV and that breaks it up into O2 and O and the cycle begins again - It is very effective at screening UV AND results in no net loss of ozone as it is continually recycled in this process. -

Know the ozone cycle and how it proceeds

See the figure in the lecture that goes over this

Why does temperature increase in the stratosphere?

The absorption of UV radiation does cause a slight warming in the stratosphere

What is a Dobson unit?

- 1 Dobson unit is 0.01mm thick. So 1 dime is 100 DU.

Who was Dobson?

The amount of ozone is measured in Dobson Units (DU) after one of the first scientists to investigate it. He designed the instrument used to measure ozone

What is the average thickness of the ozone?

If we compress all the ozone in the stratosphere together it would only be about 300DU thick on average

What is ozone thickness also a measure of?

The thickness of ozone is essentially a measurement of how much UV makes it to the surface of the earth aka uv exposure received. Less ozone, more uv, faster sunburn

Where is ozone primarily made?

Ozone is typically only 260DU in the tropics and higher elsewhere (not talking about depleted layers). - It is made in the tropics but transported by atmospheric circulation to the poles and to the lower stratosphere of the high latitudes.

Why is ozone not highest where it is made?

It is made in the tropics but transported by atmospheric circulation to the poles and to the lower stratosphere of the high latitudes.

What is a selective gas?

Selective gases absorb and emit radiation only at certain wavelengths

What does ozone absorb?

Ozone is selective in that it absorbs in the UV - primarily UV-C (most dangerous) and some UV-B, UV-A is partially absorbed - Without this process life would not exist on this planet

Know the ozone destruction cycle

Initial step in depletion is due to release of gases containing Cl and bromine (focus on cl since book does) theses are know as Ozone depleting substances(ODS) or source gases - Primary thing responsible are called CFCs - chloroflurocarbons which were developed as a non toxic alternative to dangerous sustances such as ammonia for use in spray can propellants. Refridgeration etc - So CFCs are released and converted into reactive halogen gases by UV radiation from the sun - at this stage chlorine nitrate and hydrogen chloride are the two most abundant. We call them reservoir gases as they do not react directly with ozone but do provide a Cl reservoir for its destruction. - These gases are transported to the poles. The gases are changed into highly reactive chlorine - a process we will discuss as this lecture proceeds - The Cl reacts with ozone to form chlorine monoxide and O2 - Chloride monoxide is also highly reactive and it reacts with molecular oxygen to produce more Cl and O2 - Cycle then starts over again - The chlorine is acting as a catalyst because ClO and Cl keep being reformed, one CL atom can participate in many many cycles.

What are CFCs?

CFCs - chloroflurocarbons

Who first proposed the CFC link with ozone?

The link between CFCs and ozone depletion was first suggested by Rowland and Molina and UC-Irvine in 1974. Fiercely rejected by chemical industry. 1995 received Nobel Prize - first to go to Environmental Science

What is a reservoir gas? Know the two main reservoir gases.

chlorine nitrate and hydrogen chloride. We call them reservoir gases as they do not react directly with ozone but do provide a Cl reservoir for its destruction.

Why is Cl important for ozone destruction?

it reacts with ozone and destroys it in the process

How do CFCs result in reservoir gases?

So CFCs are released and converted into reactive halogen gases by UV radiation from the sun

How does chlorine destroy ozone?

The Cl reacts with ozone to form chlorine monoxide and O2 - Chloride monoxide is also highly reactive and it reacts with molecular oxygen to produce more Cl and O2 - Cycle then starts over again

Why is a Cl a catalyst?

The chlorine is acting as a catalyst because ClO and Cl keep being reformed, one CL atom can participate in many many cycles.

Understand the formation of the ozone hole above the South Pole

ODS like CFCs are broken down into a number of reactive halogen gases in the atmosphere as this figure shows - The worst of these is ClO (chlorine monoxide) (and Cl atoms) but in the lower latitudes only a small amount of them exists - Over higher latitudes the situation is different. We can see the abundance of HCl (hydrogen chloride) and chlorine nitrate (ClONO2) that are present - these come into play in the polar climate. In Mid march winter arrives in antarctica and are vortex of very cold air forms above the continent and it isolates the air there in the middle and lower polar stratosphere from the rest of the earth - This means that transport in and out of the vortex doesn't really happen. When temperatures drop below -78C as they do in the Antarctic winter, nitric acid and other sulfur containing gases condense with water vapor to form polar stratospheric clouds, as seen here - The chlorine reservoir species we have been discussing - the hydrogen chloride and chlorine nitrate collect on these clouds and they react with them. Molecular clorine (Cl2) leaves the PSC and HNO3 remains - These reactions are called dark reactions as they only occur during 24 hours of darkness in polar winter

When does the ozone hole form above the South Pole? Understand and know the cycle that I walk you through.

August - november. As soon as sun starts to rise after winter until polar vortex ends. Worst three weeks are end of september to mid October.

How is the ozone hole defined?

Hole defined to be region below 220 Dobson units located south of 40degrees south

Why was the 2019 hole the smallest?

thanks to abnormal weather patterns in the upper atmosphere over Antarctica that dramatically limited ozone depletion in September and October.

How big has the ozone hole grown to?

around the size of N America

What is the polar vortex and why does it form?

Mid march winter arrives in antarctica and are vortex of very cold air forms above the continent and it isolates the air there in the middle and lower polar stratosphere from the rest of the earth - This means that transport in and out of the vortex doesn't really happen.

What are PSCs and how and why do they form?

polar stratospheric clouds. When temperatures drop below -78C as they do in the Antarctic winter, nitric acid and other sulfur containing gases condense with water vapor to form polar stratospheric clouds

Why are they key for ozone destruction?

The chlorine reservoir species we have been discussing - the hydrogen chloride and chlorine nitrate collect on these clouds and they react with them

What is a dark reaction? What is an example of this?

HCl + ClONO2 → Cl2 + HNO3 Molecular clorine (Cl2) leaves the PSC and HNO3 remains - These reactions are called dark reactions as they only occur during 24 hours of darkness in polar winter

How do we create free chlorine over the South Pole?

First we have the reservoir gases present in the stratosphere which is cut off due to the polar vortex - we get below -78C and PSCs form from nitric acid and other sulfur containing gases condensing. Then the hydrogen chloride and chlorine nitrate (reservoir gases) collect on the PSCs - They react to form molecular chlorine and nitric acid. The nitric acid stays on the PSCs and the molecular chlorine collects in the stratosphere. As the sunlight returns to the polar region, the molecular chlorine is broken apart into free chlorine (photolyzed) by UV light - This creates a lot of free Cl which can react with Ozone and deplete it rapidly. The low temp is why we do not have a similiar big hole above the artic - that T is not reached for a long enough period of time

Why does the ozone hole form when it does?

because this is when a lot of free Cl is produced as the sunlight breaks apart molecular chlorine. Antarctica does not get any sun over the winter, so this process starts when it returns. The free Cl remains there until the polar voretx stops

What is the Montreal Protocol? What did it do?

Montreal protocol - restricted CFC production - international agreement in 1987 - 27 nations signed this protocol and agreed to a 50% reduction in CFCs by 1999 - It has been subsequently refined several times when it was realized 50% would not be sufficient and other substances should be added in addition to CFCs - 1990 London amendments had 80 nations sign called for phase out of most damaging ODS by 2000 in developed nations and 2010 for developing nations - 1992 - Copenhagen amendment - complete phase out of cfcs ind eveloped nations by 1996 and reduction or phase out of HCFCs (less destructive replacement) by 2030 - 6 amendments since then - Some argue montreal protocol has been the single most significant international agreement

What was the London amendment?

1990 London amendments had 80 nations sign called for phase out of most damaging ODS by 2000 in developed nations and 2010 for developing nations

What was the Copenhagen amendment?

1992 - Copenhagen amendment - complete phase out of cfcs ind eveloped nations by 1996 and reduction or phase out of HCFCs (less destructive replacement) by 2030

Why has there not been a quicker recovery to the ozone hole?

We have seen some recovery, but problem is that the CFC molecules have atmospheric lifetimes from decades to century so it takes a long time for them to disappear

What is global warming?

average global surface temperature increase largely from human emissions of greenhouse gases

What is climate change?

how the climate changes through time. Includes global warming and everything else that increasing greenhouse has amounts will affect (precipitation, sea-level, etc.)

What is the greenhouse effect?

process that occurs when gases in Earth's atmosphere trap the Sun's heat.

What is the abundance of CO2 in our atmosphere?

0.04165% or 416.5ppm

What is the overall composition of our atmosphere?

N=78%, O=21%

Why is CO2 important in terms of global warming?

It is a greenhouse gas - warms up the atmosphere

What is the energy balance formula? Know what each term means. Understand how it works

∆S= I- O change in energy stored in the earths atmosphere (∂S) is equal to how much energy is put in from the sun and how much energy leaves. This is called the energy balance

What objects emit EM radiation?

Any object warmer than 0degrees K gives off electromagnetic radiation

How is the energy of EM radiation carried?

Energy of electromagnetic radiation is carried by photons

What is the relationship between wavelength and energy?

inversely proportional, Smaller wavelength, higher energy.

What happens to the incoming solar radiation once it reaches Earth? You should be able to label this figure (slide 12)

As solar radiation passes through the atmosphere, about 30% is reflected off clouds and the earths surface itself - reflected). - About 19% of the radiation from the Sun gets absorbed by the atmosphere - The rest (51%) strikes the Earth's surface and warms it. - - So what happens to that 51% after it heats the Earth? - Some is transported into atmosphere by convection currents (warm rising air), some just leaves directly from surface, some is transported in water vapor and is released when it condenses - Where do greenhouse gases figure into this?

What is albedo?

The albedo of the surface tells you how reflective a surface is. The ratio of the solar radiation reflected by a surface to the total incoming solar radiation (how much lands on the surface and how much of that is

What is the difference between the energy released by the Sun and the Earth?

shortwave (incoming) and longwave (terrestrial/outgoing)

What is a selective gas?

It absorbs only certain wavelengths

How does the greenhouse effect work?

The radiation coming in is mostly absorbed at the surface. - CO2 absorbs only radiation in the longwave region. What does this mean? - Solar energy passes through CO2 on its way to the ground because it isn't the right wavelength to be absorbed, it's invisible to it. - However, the heat the earth radiates back to space DOES get absorbed by CO2 and that stops the heat from leaving the earth and warms our atmosphere.

Where does CO2 absorb energy from in the EM spectrum?

longwave

Why does CO2 not absorb incoming solar radiation?

because it isn't the right wavelength to be absorbed - carbon dioxide is a selective gas

Why are greenhouse gases important?

greenhouse gases are very important because without them it would be about -18 degrees C at the surface. The gases warm it by 33 degrees!

Why is Venus so hot?

Venus has far more greenhouses gases and a surface temp hot enough to melt lead - It absorbs LESS radiation but heats up more because of how much CO2 is in its atmosphere