Lecture 3 - Atmospheric Environment I PDF

Environment and Development Dr. Stavros G. Poulopoulos ATMOSPHERIC ENVIRONMENT  The Importance of Atmosphere (I) Earth is surrounded by a thin layer of gases that is called atmosphere. It is characterized thin because it is about 100-150 km above the sea level and the average r...

Environment and Development Dr. Stavros G. Poulopoulos ATMOSPHERIC ENVIRONMENT  The Importance of Atmosphere (I) Earth is surrounded by a thin layer of gases that is called atmosphere. It is characterized thin because it is about 100-150 km above the sea level and the average radius of earth is 6370 km. Yet, this thin layer affects numerous processes that take place on earth: ✓ It keeps a global surface average temperature of 15oC that is favorable for the life forms evolved on earth; ✓ It contains today about 1.20×018 kg of oxygen, a level probably reached not later than 25 million years ago. Respiration of humans and animal life is absolutely depended on this oxygen; ✓ It acts as a filter for dangerous radiation from sun. Atmosphere filtrates 95% of the harmful ultraviolet part of solar radiation via ozone layer; The Importance of Atmosphere (II) ✓ The continuous interaction of the gases contained in the atmosphere with solar radiation regulates the flow of energy through the climate system, and determines Earth’s climate. ✓ Atmosphere as a part of biosphere interacts continuously with hydrosphere and lithosphere; ✓ Outer space is full of potentially dangerous objects like asteroids, comets, meteoroids, and even man-made satellites. Atmosphere burns all these objects before they getting crashed on Earth’s surface, protecting thus again life on Earth; The Composition of Atmosphere  The Stratification of Atmosphere (I) Earth’s atmosphere is composed of a number of layers. The way in which these layers are defined depends on the property considered. The vertical distribution of temperature, pressure, density, and composition of the atmosphere constitutes atmospheric structure. if the concentration of atmospheric gases is taken into account, then atmosphere is divided into: ✓ Homosphere: It is the lower part from the surface of the earth to a height of 80-100 km above the earth. ✓ Heterosphere: Starting from the upper portion of homosphere, it extends to a height of 500 km above the earth. ✓ Exosphere: The part of atmosphere above about 500 km is called exosphere. The Stratification of Atmosphere (II)  Scales of Air Pollution Local level. Air pollution at this level concerns generally a region within a maximum 5-km radius. Urban level. This level is related to air pollution observed in cities: winter-type smog and photochemical smog. Regional level. Regional air pollution affects large areas of 50- 1000 km magnitude: tropospheric ozone and acidifying substances like SO2 and NO2. Transboundary level. The extent regards regions of 1000 km and the “exchange” of air pollution between countries or even continents. Global level. Global warming and stratospheric ozone depletion.  Health Effects (I) Most production or daily activities like industrial manufacture, agriculture, transportation, cooking, smoking, etc. are accompanied by the release of numerous compounds into the atmosphere. Any process related to energy production, transfer, and finally use has an inevitable result: air pollution. Air pollution is not a new phenomenon; in medieval times, the burning of coal was forbidden in London while Parliament was in session. New important data are being accumulated day after day about the potential adverse health effects resulting from air pollution. In 2014, WHO announced that air pollution is now the world’s largest single environmental health risk, resulting in 7 million premature deaths in 2012 worldwide. namely one in eight of total global deaths. Health Effects (II) Health Effects (III) Health Effects (IV) Health Effects (V)  Air Pollution Impact The cost of air pollution to the world’s most advanced economies plus India and China is estimated to be US$3.5 trillion per year in lives lost and ill health. In OECD countries the monetary impact of death and illness due to outdoor air pollution in 2010 is estimated to have been US$1.7 trillion. In addition, air pollutants contribute to atmospheric problems such as acidification and global climate change, which have impacts on crop productivity, forest growth, biodiversity, buildings, and cultural monuments.  Air Pollutants and Sources Air pollutants are also classified into two broad categories: ✓ Primary; ✓ Secondary.  Local Level Local air pollution refers to elevated ambient concentrations of compounds over a small area, caused by a large local emitter releasing these compounds into the atmosphere or many small emitters gathered like cars. Even in a small village, the concentration of livestock farms and activities can result in local air pollution. The emissions of a variety of compounds like sulfur dioxide, nitrogen oxides, carbon monoxide, fine PM, organic compounds like benzene, toluene and polycyclic aromatic hydrocarbons (PAHs), and heavy metals in PM (lead, cadmium), can cause local concentrations to reach levels that are harmful to human health.  Urban Level (I) High annual average concentration levels of various pollutants, e.g., benzene, lead, sulfur dioxide (SO2), and PM. As in the case of air pollution at the local level, this type of pollution is linked to specific pollutants resulting from either large industrial and power plants or automotive vehicles.  Urban Level (II) Winter-type smog, characterized by high concentrations of SO2 and PM that arise mainly from the combustion of coal and fuels with a high content of sulfur. This kind of pollution occurs in urban areas with many power plants or industrial units clustered together, where low temperatures and mist are observed in the year. It has been also termed “industrial pollution.” Central heating systems are also major contributors, especially in low- income or developing countries. Summer-type smog, characterized by high concentrations of carbon monoxide, VOCs, and nitrogen oxides (NOx). It is also called “photochemical smog” or “LA smog,” since it first appeared in Los Angeles. This type of pollution is closely connected to automotive vehicles, and its formation is favored by sunlight and high temperatures.  OECD Classification of Sources (I) The Organization for Economic Co-Operation and Development (OECD) has developed an extensive database (OECD.Stat) with the annual releases of many pollutants for many countries around the world. Pollutants are related to one or more of the following anthropogenic sources: 1. Total mobile sources a. Road transport b. Other mobile sources 2. Total stationary sources a. Power stations b. Combustion i. Industrial combustion ii. Other combustion d. Industrial processes e. Solvents OECD Classification of Sources (II) f. Miscellaneous i. Agriculture ii. Energy iii. Waste?. Regional and Transboundary Level (I) Air pollution at these levels can be attributed to two mechanisms: ✓ transport and dispersion of urban pollutants over large areas, and ✓ transport and transformation of primary pollutants into secondary ones. Three kinds of environmental issues are connected to these mechanisms: ✓ spread of tropospheric ozone, ✓ acidification, ✓ and eutrophication, all of them having serious consequences to crops, aquatic life, and forests. Regional and Transboundary Level (II) The problems that appear on a regional level may also be exchanged between adjacent countries. Transboundary air pollution is related to the transfer of air pollution from one country to another. For example, Greece exchanges ozone with Italy, whereas Japan and Canada “import” various types of air pollution from China and the United States, respectively. Moreover, the transboundary transport of acidifying pollutants has led to a marked change in the acidity of lakes and streams in Scandinavia, as observed in the 1960s. Air pollution problems seem also to travel across different continents. Emissions from East Asia significantly impact the air arriving to North America. North America “exports” air pollutants to Europe. Acidification