Chemistry of the Environment 3.2 Atmospheric Chemistry PDF

11/26/2024 MODULE 3 ENG 201 Intended Learning Outcomes - ILOs...

11/26/2024 MODULE 3 ENG 201 Intended Learning Outcomes - ILOs Explain the composition of the CHEMISTRY of the atmosphere. ENVIRONMENT Discuss major air pollutants and 3.2 Atmospheric Chemistry their sources. FACULTY OF ENGINEERING Discuss greenhouse gases and UNIV E RS IT Y OF S ANTO TOM AS the greenhouse effect. M ANIL A, P HIL IP P INE S UST FACULTY OF ENGINEERING 1 2 Why Should Engineers Care About Atmospheric Chemistry? Composition of Earth’s atmosphere Air Pollution Control: Designing systems to reduce air pollution by volume requires knowledge of the chemical reactions involved in pollutant By volume, the dry air in Earth’s formation and removal. atmosphere is about 78.08 percent Climate Change Mitigation: Engineers play a crucial role in developing nitrogen, 20.95 percent oxygen, and 0.93 technologies to mitigate climate change. This involves understanding percent argon. the greenhouse effect and the role of atmospheric gases in driving climate change. A brew of trace gases accounts for the Material Science and Corrosion: Atmospheric conditions, including other approximately 0.04 percent, including pollutants and humidity, can significantly impact the durability of the greenhouse gases carbon dioxide, materials. Engineers need to consider these factors in designing methane, nitrous oxide and ozone. The structures and products. concentration of water vapor varies Environmental Impact Assessment: Engineers often need to assess the significantly depending on temperature. environmental impact of projects, which includes understanding how emissions from these projects might affect air quality and climate Source: https://science.nasa.gov/earth/climate-change/greenhouse-gases/the-atmosphere- change. getting-a-handle-on-carbon-dioxide/ UST FACULTY OF ENGINEERING 3 UST FACULTY OF ENGINEERING 4 3 4 Composition of Earth’s atmosphere by volume Layers of the Atmosphere Source: https://www.noaa.gov/jetstream/atmosphere 1. Troposphere: Lowest layer closest to Earth's surface. Contains most of the atmosphere's mass and where weather occurs. Temperature decreases with altitude. 2. Stratosphere: Contains the ozone layer, which absorbs harmful UV radiation. Temperature increases with altitude due to ozone absorption of UV radiation. Relatively stable layer with little weather activity. UST FACULTY OF ENGINEERING 5 UST FACULTY OF ENGINEERING 6 5 6 1  11/26/2024 Layers of the Atmosphere Air Pollution 3. Mesosphere: The major air pollutants occur either Temperature decreases with in gaseous forms or as particulate altitude. Meteors burn up in this layer, matter (PM). creating shooting stars. 4. Thermosphere: Temperature increases rapidly with altitude due to absorption of high-energy solar radiation. Home to the International Space Station. Aurora Borealis and Australis occur in this layer. Source: https://www.torranceair.org/resources.html 5. Exosphere: Outermost layer where the The gaseous pollutants include sulfur dioxide (SO2), nitrogen oxides (NOx), carbon atmosphere gradually fades into monoxide (CO), ozone (O3), and volatile organic compounds (VOC) such as space. hydrocarbons (compounds containing only carbon and hydrogen that include Satellites orbit in this layer. petroleum products), hydrogen sulfide (H2S), and hydrogen fluoride (HF). UST FACULTY OF ENGINEERING 7 UST FACULTY OF ENGINEERING 8 7 8 Air Pollution | Particulate Matter (PM) Air Pollution | Primary vs Secondary Pollutants Primary pollutants are those emitted directly into the air. They include particulates, sulfur dioxide, carbon monoxide, nitrogen oxides, and hydrocarbons. Particulate Secondary matter pollutants pollutants are are very small particles of solid produced through or liquid reactions between substances less primary pollutants, than 10 μm sunlight, and (micrometer) in natural diameter and may be organic or atmospheric gases. inorganic. Tropospheric ozone and acid rain are examples. Source: https://www.epa.gov/pm-pollution/particulate-matter-pm-basics Source: https://www.clarity.io/blog/how-measuring-different-types-of-air-pollutants-creates-a-more-holistic-picture-of-air-pollution UST FACULTY OF ENGINEERING 9 UST FACULTY OF ENGINEERING 10 9 10 Air Pollution | Primary vs Secondary Pollutants Air Pollution | Sources Source: Singh et al. (2022). Air Pollution: Sources and its Effects on Humans and Plants Source: https://www.nps.gov/subjects/air/sources.htm UST FACULTY OF ENGINEERING 11 UST FACULTY OF ENGINEERING 12 11 12 2  11/26/2024 Air Pollution | Criteria Pollutants Criteria Pollutants are a group of six common air pollutants that are identified as significant threats to public health and the environment, warranting strict regulation and control measures. 1. Particulate Matter (PM): Tiny particles in the air that can cause respiratory problems. It is categorized by size: PM10 (particles smaller than 10 micrometers) and PM2.5 (particles smaller than 2.5 micrometers). 2. Ground-level Ozone: A colorless gas formed by chemical reactions between pollutants in sunlight. It can damage lung tissue and aggravate respiratory conditions. 3. Carbon Monoxide: A colorless, odorless gas that can reduce oxygen supply to the body's organs. 4. Sulfur Dioxide: A colorless gas with a strong odor, often associated with industrial emissions and can contribute to acid rain. 5. Nitrogen Dioxide: A reddish-brown gas that can irritate the respiratory system and contribute to smog. 6. Lead: A heavy metal that can harm the nervous system, especially in Source: https://www.nps.gov/subjects/air/sources.htm children. Source: https://www.epa.gov UST FACULTY OF ENGINEERING 13 UST FACULTY OF ENGINEERING 14 13 14 Air Pollution | Criteria Pollutants Source: https://clevelandhealth.org/programs/air/monitoring/ Source: https://www.epa.gov UST FACULTY OF ENGINEERING 15 UST FACULTY OF ENGINEERING 16 15 16 Ozone high in the Earth's atmosphere protects us Ground-level Ozone from the sun's harmful radiation. Ground-level Ozone Tropospheric ozone, But at ground level, whether from natural or ozone is an air pollutant. anthropogenic sources, is Ground-level ozone formed via the same forms when nitrogen chemical reactions. Burning oxides and volatile fossil fuels or biomass organic compounds releases CO, hydrocarbons, react with each other in and NOx (NO and NO2) into sunlight and hot the atmosphere. The temperatures. hydrocarbons can then be photooxidized in the Ozone formation as the result of carbon monoxide (CO) This pollution oxidation in the presence of nitrogen oxides (NO and NO2) presence of NOx to form comes from vehicles, This reaction series produces one O3 molecule, as well as industry, and other ozone (O3). The series of oxidizing one CO molecule to CO2. The OH and NO are sources and contributes reactions for the oxidation critical to these reactions, but there is no net production to smog formation. of carbon monoxide (CO) to or destruction of either species in this sequence. carbon dioxide (CO2) is At night, NO can react with ozone to produce NO2 and O2, shown at right. decreasing the concentration of ozone. Source: https://ecology.wa.gov/air-climate/air-quality/air-quality-targets/air-quality-standards/ozone-pollution Source: https://www.whoi.edu/science/MCG/people/ehintsa/Ozone/background.html UST FACULTY OF ENGINEERING 17 UST FACULTY OF ENGINEERING 18 17 18 3  11/26/2024 Acid Rain Acid Rain While a small portion of the SO2 and NOX that cause acid rain is from natural sources such as volcanoes, most of it comes from the Acid rain results when burning of fossil fuels. sulfur dioxide (SO2) The major sources of and nitrogen oxides SO2 and NOX in the (NOX) are emitted into atmosphere are: the atmosphere and Burning of fossil fuels transported by wind to generate and air currents. electricity. Two thirds of SO2 and one fourth of The SO2 and NOX react NOX in the atmosphere with water, oxygen and come from electric other chemicals to power generators. form sulfuric and nitric Vehicles and heavy acids. These then mix equipment. with water and other Manufacturing, oil materials before falling refineries and other to the ground. industries. Source: https://www.epa.gov Source: https://www.epa.gov UST FACULTY OF ENGINEERING 19 UST FACULTY OF ENGINEERING 20 19 20 Acid Rain This image illustrates the pathway for acid rain in our environment: (1) Emissions of SO2 and NOx are released into the air, where (2) the pollutants are transformed into acid particles that may be transported long distances. (3) These acid particles then fall to the earth as wet and dry deposition (dust, rain, snow, etc.) and (4) may cause harmful effects on soil, forests, streams, and lakes. Source: https://www.epa.gov Source: https://www.eia.gov/energyexplained/energy-and-the-environment/greenhouse-gases.php UST FACULTY OF ENGINEERING 21 UST FACULTY OF ENGINEERING 22 21 22 Greenhouse Gases Greenhouse Gases Source: https://css.umich.edu/publications/factsheets/climate-change/climate-change-science-and-impacts-factsheet Source: https://geologyscience.com/geology-branches/historical-geology/greenhouse-gases-in-geological-history/#google_vignette UST FACULTY OF ENGINEERING 23 UST FACULTY OF ENGINEERING 24 23 24 4  11/26/2024 Greenhouse Gases UST FACULTY OF ENGINEERING 25 UST FACULTY OF ENGINEERING 26 25 26 MODULE 3 References: ENG 201 Botkin & Keller (2010). Environmental Science: Earth as a Living Planet https://education.nationalgeographic.org/resource/atmosphere/ https://education.nationalgeographic.org/resource/parts-atmosphere/ https://www.noaa.gov/jetstream/atmosphere https://science.nasa.gov/earth/climate-change/greenhouse-gases/the- atmosphere-getting-a-handle-on-carbon-dioxide/ CHEMISTRY of the https://www.epa.gov/pm-pollution/particulate-matter-pm-basics https://www.torranceair.org/resources.html https://www.nps.gov/subjects/air/sources.htm ENVIRONMENT https://www.whoi.edu/science/MCG/people/ehintsa/Ozone/background.htm 3.2 Atmospheric Chemistry FACULTY OF ENGINEERING UNIV E RS IT Y OF S ANTO TOM AS M ANIL A, P HIL IP P INE S UST FACULTY OF ENGINEERING 27 27 28 5