AICE Enviro Unit 7

Acid Deposition

is a mix of air pollutants that deposit from the atmosphere as either acidic wet deposition (pH<5.6) or acidic dry deposition

Wet Deposition

occurs when acids are dissolved in precipitation at great distances from the sources of the pollution

ex. snow, hail, or fog

Dry deposition

typically occurs close to the source of emission and causes damage to buildings and structures

ex. dust (fine particles) and gases

Acid Rain

• caused by human activities

• sulfur dioxide & nitrogen dioxide are released after burning fossil fuels

• Wind spreads acidic solutions

• Acid rain enters water systems through runoff that sinks into the ground

Plants/trees affected by acid rain

• harms forests, damaging tree leaves

• robs soils of essential nutrients

• harder for trees to take up water

ways humans can reduce acid rain

• designing cleaner power plant, using fewer fossil fuels.

• reduce number of pollutants that create acid rain

Primary pollutants

• are those that are directly emitted by a factory (coal powered) or automobile

  • ex. sulfur dioxide (SO₂) Nitrogen monoxide (NO) and Nitrogen dioxide (NO₂)

Secondary pollutants

• are the result of primary pollutants reacting with other substances in the atmosphere

  • ex. Sulfuric Acids (H₂SO₄) and Nitric Acids (HNO₃)

Sulfuric Acid Deposition

• Fossil Fuels contain Sulfur compounds

• Combustion of fossil fuels release sulfur dioxide gas

• Sulfur dioxide gas reacts with water and oxygen in the atmosphere to form sulfuric acid

Nitric Acid Deposition

• Nitrogen from the atmosphere reacts with oxygen in the high temperatures of vehicle engines to form nitrogen monoxide gas

• Nitrogen monoxide gas is released into the atmosphere in vehicle emissions

• nitrogen monoxide gas reacts with oxygen and water in the atmosphere to form nitric acid

Impacts of Acid deposition on Aquatic Ecosystems

• Ecological effects of acid rain are most clearly seen in aquatic environments, such as streams, lakes, and marshes where it can be harmful to fish and other wildlife.

  • As it flows through the soil, acidic rainwater can leach aluminum from soil clay particles and then flow into streams and lakes.

  • The more acid that is introduced to the ecosystem, the more
    aluminum is released.

• Some types of plants and animals are better able to tolerate acidic waters and moderate amounts of aluminum.

  • Others, however, are acid-sensitive and will be lost as the
    pH declines.

    • Generally, the young of most species are more sensitive to environmental conditions than adults.

      • At pH 5, most fish eggs cannot hatch.

• At lower pH levels, some adult fish die.

  • Some acidic lakes have no fish.

  • Even if a species of fish or animal can tolerate moderately acidic water, the animals or plants it eats might not.

    Ex: Frogs have a critical pH around 4, but the mayflies they eat are more sensitive and may not survive below pH 5.5.

    
    

Impacts of Acid deposition on Vegetation and crops

High concentrations of dissolved aluminum released from soils often
enter streams and lakes.

• In conjunction with rising acidity in aquatic environments, aluminum
  can damage/destroy fish gills thus impairing fish respiration.

REMEMBER: Acidity = Higher hydrogen ion (H+)
concentration and lower pH.

• Essential nutrients in the soil such as calcium, potassium, and magnesium can be leached from soil as it becomes more acidic. This is detrimental to plant health (both trees and crops). Results in LOWER crop yield!

• Root hairs are damaged which results in less uptake of water from the soil (both trees and crops).

Both direct and indirect effects of acid deposition lead to defoliation (loss of leaves/needles).

• Acid deposition can strip nutrients from trees’ foliage, leaving them with brown or dead needles/leaves.

• When this happens, trees are less able to absorb sunlight to perform photosynthesis. This makes trees weak and less able to withstand freezing temperatures and disease.

Impacts of Acid Deposition on Stone and Brick Buildings

The weathering of rocks by chemicals (such as acids) is called
chemical weathering.

• Acid rain makes chemical weathering happen more quickly.

• As a result, buildings made from rocks/concrete are damaged. The
  type of rock most quickly affected is limestone.

• Limestone buildings and statues (including many with great
  archaeological and historical value) react with acid and simply
  dissolve.

Photochemical Smog

a mixture of air pollutants and particulates, including ground level ozone, that is formed when oxides of nitrogen and volatile organic compounds (VOCs) react in the presence of sunlight

• forms when sunlight drives chemical reactions between primary pollutants and atmospheric compounds, producing a mix of more than 100 different chemicals, tropospheric ozone often being the most abundant.

  • Because photochemical smog also includes NO2, it
    generally appears as a brownish haze.

    
    

Industrial smog

is created primarily by the burning of coal (power plants)

• Soot (particulate matter) and Sulfur Dioxide are produced as a result of combustion of coal

  • This mixture forms smog where reactions of sulfur dioxide, atmospheric oxygen, and water vapor result in sulfuric acid mixed with the smog.

Vehicle contribution

• Most smog pollution in urban areas result largely from automobile exhaust

• Vehicles contribute Ox, SOx, and VOCs to the atmosphere. Some of these pollutants react with sunlight, so photochemical smog pollution tends to be worse in cities with sunny climates. Ex: Los Angeles and Mexico City.

Helps promote photochemical smog

Hot, sunny, windless days in urban areas provide perfect conditions for photochemical smog to form.

• On a typical workday, exhaust from morning traffic releases NO and VOCs into a city’s air.

• Sunlight promotes the production of ground-level (tropospheric) ozone and other secondary pollutants, leading to a midafternoon peak in pollution.

Impacts of Photochemical smog

• Photochemical smog irritates people’s eyes, noses, and throats, and over time can lead to asthma, lung damage, heart problems decreased resistance to infection, and even cancer.

• Photochemical smog can lead to decreased crop yield due to decreased photosynthesis and poor plant health.

• The chemical make-up also deteriorates plastics and rubber.

Strategies to manage air pollution

• Reduction of Fossil Fuel Use

• Reduction of Emissions:

• SOx, NOx, VOCs, and Particulate Matter

• Restriction of Vehicle Use in Urban Areas

• Legislation

Reduction of Fossil Fuel use

• Reduce demand of private car use

  • Mass Transit or Ride Sharing

  • Drive less and walk/bike/bus more

• Reduce consumption of electricity through building design & renewable energy sources

  • small scale green power on city buildings through solar, wind, locale power stations away from urban areas

  • Renewable, non-pollution emitting energy sources (solar, wind, hydro) Alternative (nuclear) energy during transition to renewable energy dependency

• Eat local, eat more plants, less meat - less processing

Reduction of Sulfur Dioxide

• Flue Gas Desulfurization

  • Dry scrubbers

  • wet scrubbers

  • a flue is a smokestack

• Hydrodesulfurization or hydrotreating

  • A catalytic chemical process widely used to remove sulfur compounds from refined petroleum products such as gasoline or petrol, jet fuel, diesel fuel, and fuel oils

Why reduce Sulfur Dioxide

One purpose for removing the sulfur is to reduce the sulfur dioxide emissions resulting from using those fuels in automotive vehicles, aircraft, railroad locomotives, ships, or oil burning power plants, residential and industrial furnaces, and other forms of fuel combustion.

Reduction of Nitrogen Oxide emissions

• Catalytic Converters have been around since 1975.

  • This device converts harmful pollutants such as carbon
    monoxide and oxides of nitrogen from a combustion engine’s
    exhaust into less harmful molecules like CO2, water, and nitrogen.

Sources of Volatile Organic Compound

• Household products

  • paints, paint strippers and other solvents

  • wood preservatives

  • aerosol sprays

  • cleansers and disinfectants

  • moth repellents and air fresheners

  • stored fuels and automotive products

  • hobby supplies

  • dry-cleaned clothing

  • pesticide

Reducing Volatile Organic Compounds

• increase ventilation when using products that emit VOCs

• Meet or exceed any label precautions (including proper disposal)

• Do not store opened contained of unused paints and similar materials within the school

• Formaldehyde, one of the best-known VOCs, is one of the few indoor air pollutants that can be readily measured.

Reduction of Particulate Matter

• Electrostatic Precipitators

  • Particles are electrostatically charged in the gas stream.

  • Charged particles stick to collection plates.

  • Clean air exits through a stack to the atmosphere.

  • Plates are shaken by mechanical rappers to remove particles.

  • Particles fall into a hopper and are moved for disposal or recycling.

Restriction of vehicle use in Urban areas

Legislation

• local and national government can encourage individuals through educational campaigns and economic incentives

  • energy efficiency in homes

  • reduction of carbon footprints

  • reduce, reuse, recycle

  • replacement of chemical fertilizers with organic fertilizers

Geneva Convention on Long Range Transboundary Pollution 1979

controlling and reducing air pollution across borders by internation corporation

Montreal Protocol 1987

ban and controlled use of CFCs to slow down ozone depletion.

has been the most successful international agreement in reducing/eliminating the production and use of ozone depleting substances.

• Once the protocol was signed the regulation went into effect, causing surface levels of ozone depleting substances to go down 

• The Ozone hole is becoming smaller because of decline in Chlorine released from Chlorofluorocarbons  

• Substances get high up in the stratosphere and the chlorine gets released from the chlorofluorocarbons, which is what destroys the ozone.  

• Hydrogen chloride in the atmosphere measured over time shows that the HCl, reactive chlorine that destroys the ozone, the levels are going down inside the Antarctic ozone hole.  

• Ozone levels can vary depending on temperature 

• If warm not as much ozone depletion, if cold more ozone depletion 

• Microwave Limb Sounder (MLS) shows data that ozone depletion has declined

Rio Earth Summit 1992

Agreement Agenda 21 passed with aim to cut environmental pollution and conserve and wildlife habitats

Kyoto Protocol

signed by over 100 countries to cut carbon dioxide emissions by 5%, compared with 1990 levels. Each HIC was allotted a target on emission reductions. Some LICs, such as China, were given no targets and were allowed to increase emissions

Gothenburg Protocol

Aimed to reduce pollutants and levels of acid rain and tropospheric ozone

Copenhagen Conference 2009

HICs and some LICs agreed to limit on greenhouse gas emissions. To assist LICs with the reduction, $30 billion was offered as aid by HICs, increasing to $100 billion by 2020. However, was not legally binding

Paris Climate Conference 2015

195 countries agreed to limit rise in global temperature to 2C. European Union will cut carbon dioxide emissions by 40% in 2030, the US by 28% by 2025, and China agreed their emissions will peak in 2030. Countries will meet every 5 years to discuss progress.

Polluter Pays Principle

The 'polluter pays' principle is the commonly accepted practice that those who produce pollution should bear the costs of managing it in order to prevent damage to human health or the environment.

Air Quality in the U.S.

1. leads to health problems, particle pollution can infiltrate blood and cause heart attacks and strokes.  

2. Impacts economy, roughly costing three percent of its GDP in damages or $617 billion 

3. It can cause people to cough, wheeze, and have shortness of breath.  

Ozone Depletion

Step 1: Chlorofluorocarbons (CFCs) from aerosols and refrigerants are unreactive compounds and are not broken down in the troposphere.
Step 2: CFCs move into the stratosphere and break down in the presence of ultraviolet light to release a chlorine atom.
Step 3: Rapid reactions between chlorine atoms and ozone breaks down ozone (O3) into oxygen (O2), causing ozone depletion.

Step 4: Chlorine atoms remain in the stratosphere and can continue to destroy ozone.

Measuring Ozone

Ozone concentration is measured using the Dobson Unit.

An ozone hole is an area where the average concentration of ozone is below 100 Dobson Units.

• The sun emits large amounts electromagnetic radiation in all directions  

• Visible light is the small fraction of this radiation the human eye can see 

• Below visible light is ultraviolet which is divided into UVA UVB and UVC 

• Ozone layer protects the Earth from these bands 

• UVA is not blocked by the ozone layer, accounting for 97% of the solar Uv energy reaching near the surface 

• UVB is absorbed by the ozone layer, accounting for remaining 5% 

• UVC is the most damaging UV radiation, is completely absorbed by the ozone in the upper atmosphere, no measurable amount reaches the Earth’s surface.  

Antarctica Ozone Depletion

Factors include: temperature, polar vortex, and polar stratospheric clouds (PSCs).

• Polar Stratospheric clouds, man made CFCs, and intensive heat from the sun decimates huge portions of the ozone layer.  

• The ozone layer is important because it blocks harmful UV radiation from the sun.  

• CFCs are exposed to ultraviolet radiation in the stratosphere, due to chlorine in CFCS 

• Montreal Protocol made to decrease CFCs 

• Many research stations are in the arctic to measure the cleanest air on earth and monitor the ozone layer through high resolution data 

• In dark winter patterns stabilize around Antarctica preventing warm air from mixing in, creating the Antarctic Polar Vortex 

Impacts of increased UV Radiation

Deterioration of the ozone layer results in an increase in harmful UV Radiation reaching the Earth’s surface

• cataracts and skin cancer

• decreased crop yield

• decreased biodiversity of terrestrial (forests) and aquatic (plankton) ecosystems

• Degradation of materials used in clothing and construction

Impacts of Alternatives to Ozone Depleting substances

Alternatives to CFCs:

• Hydrofluorocarbons HFCs are greenhouse gases (GHGs) commonly used by federal agencies in a wide variety of applications, including refrigeration, air- conditioning (AC), building insulation, fire extinguishing systems, and aerosols. HFCs have high global warming potential (GWP), raising concern about their impacts as they become increasingly used as replacements for ozone-depleting substances (ODS), and as economic growth spurs demand for new equipment, especially in the refrigeration/AC sector.

• Fluorinated Gases (F-GHGs) include the most potent and longest lasting greenhouse gases emitted by human activities. These are emitted as a byproduct of aluminum production and electronics manufacturing.

Rowland and Molina

• Initially the main hypothesis was not accepted b/c some of the auxiliary hypotheses were not supported by experimental evidence. 

• The hypothesis led to further research and data collection by other scientists, which confirmed that CFCs are ozone depleting. 

Ultra-Low Emission

Ultra-Low Emission Zones encourage use of electric vehicles; fines for non-compliance; reduction in vehicle emissions; improves air quality / air is cleaner; especially in areas of high population;