Atmosphere and Air Pollution Chapter 18

Quick Recap

So how have humans altered the atmosphere?

Pollution: What is it? Pollution: Any undesirable change in physical, chemical, or biological characteristics of air, soil, water, or food. It can adversely impact health of organisms. Air pollution: any chemical(s) in the air that occur in high enough concentration(s) which harms life or has a negative impact on the environment.

Where does pollution come from? Nonanthropogenic Dust particles in wind Wildfires Volcanic eruption Plants Natural decay Anthropogenic Industry Transportation Forest fires Fertilizers Energy power plants Homes / buildings manufacturing

Primary Pollutants Chemicals that are pollutants as they are released. CO, CO 2, CH 4, SO 2, NO, NO 2, N 2 O. Secondary Pollutants Form when 1 o pollutants react in some chemical reaction. O 3 in photochemical smog SO 3, HNO 3, H 2 SO 4 all part of acid deposition.

How is Air pollution measured? 1.Outdoor air pollution uses Air Quality IndexAir Quality Index 2.Which measures the 6 criteria pollutants PollutantSourceHuman Health Impact SPM Road ways, industry, other forms of combustion Respiratory problems, heart attacks Carbon Monoxide incomplete combustion, cars, fires, cigarettes industry smokestacks Decrease ability to transport oxygen through blood by binding to hemoglobin Nitrous Oxide Vehicle emission (primary and secondary pollutant) Respiratory problems Sulfur Dioxide Coal burningRespiratory problem Lead Leaded gasoline, lead smelters, lead paint Persistent pollutant accumulates in bones, can lead to liver / kidney failure/mental retardation Ozone Photochemical smog and car exhaust Respiratory problems and eye irritant

Air Quality Index Links pollution to human health

Photochemical Smog Photo= sun Chemical = reaction Photochemical reaction = reaction that takes place due to solar energy Photochemical smog normally occurs in populated cities. Brown smog

Photochemical Reactions

Industrial smog Characterized by the gray color Due to burning of Coal and Release of Sulfur into the atmosphere

Industrial Smog Reaction of burning coal C + O 2  CO 2 2C + O 2  2CO S + O 2  SO 2 WHAT HAPPENS IN TROPOSPHERE? 2SO 2 + O 2  2SO 3 react w/ H 2 O SO 3 + H 2 O  H 2 SO 4 react with ammonium H 2 SO 4 + 2NH 3  (NH 4 ) 2 SO 4 Mixture of sulfur dioxide, sulfuric acid + suspended particles

Photochemical smog Heat increases [O 3 ] + UV increases [No x ] which worsens smog Industrial smog – Mixture of SO 2 + Sulfuric acid + SPM Brownish color Gray coloration

What contributes to Smog? Climate and topography – Valleys more susceptible to smog Population density – More people more emissions Industry – Coal burning Fuel used Pollution can decrease with – Rain / snow and wind Can be negative bc pollution prevent water droplets from forming and prevents rain. Air pollution increases with – Urban buildings that slow wind speed. – Hills and mtns decrease air flow – High temp. promotes rxn

What happens when we add other natural processes into the mix? Normal scenario – Sun warms bottom air that rises ad then mixes with cooler air dispersing pollutants

Temperature inversion – Cool air is trapped under warm air and can’t rise prevents mixing and increases [pollution] Inversions seen at 1. Valleys surrounded by mountains 2. populated cities with sunny environment, light wind and surrounded by 3 sides of mtns.

Subsidence Temperature Inversion At High altitudes where a mass of warm air moves and floats over colder air, prevents mixing. California Coast: photochemical smog. High pressure from coast creates descending warm air that stays above cool coastal breeze.

Radiation temperature inversion Occurs at night when air at ground cools faster than higher air Ends when the sun rises and warms surface London Smog Disaster 1952

London Smog Disaster of 1952