Chapter Twenty Two
Air Pollution
The atmosphere has always been a sink for gaseous or particulate wastes. When the amount of waste entering the atmosphere in an area exceeds the ability of the atmosphere to disperse or degrade the pollutants, problems result. This section should foster your understanding of the materials in the text on this subject, as well as provide resources for help in answering the "Critical Thinking Questions." ENVIRONMENTAL ISSUE - How Does Arctic Haze Affect the Environment? A dark gray haze, full of industrial pollutants, hovers over the ground and extends to an altitude of 8 km (5 miles). It is not Los Angeles, London, or Prague, but thousands of miles from heavy industry in the frozen Arctic. The haze extends from Alaska to Norway, an area as large as North America, each year from November to April, and then disappears for the summer months. Scientists describe this as an aerosol, that is, microscopic particles dispersed in a gas, smoke, or fog. They have found dust from Mongolia and sea salt in the haze, but of greater concern are the pollutants, mainly sulfates, carbon soot, organic compounds, and toxic metals, including mercury, lead, and vanadium. The gaseous atmosphere itself contains elevated levels of carbon monoxide, as well as chemicals destructive of the ozone layer. Knowing the types of fuel used in various regions of the world, scientists have used the ratios of six elements (arsenic, antimony, zinc, indium, manganese, and vanadium) to a seventh, selenium, to identify the sources of the pollution. For example, manganese was present in much greater amounts and vanadium in much lesser amounts in the haze than in emissions typical of North America. Combined with knowledge of air circulation, scientists have identified Eastern Europe and Russia as the major sources of Arctic air pollution, with a significant but lesser contribution from the United Kingdom and Western Europe. The major atmospheric forces driving the pollution from these sources begin with the large difference in temperature between the equator and the poles in winter, creating strong air currents from zero to ninety degrees latitude. They are also propelled by seasonal lows in the North Atlantic and highs on the Eurasian continent, which are trapped by mountain ranges. Once the masses of pollutant-laden air reach the dry, stable air of the Arctic winter, they from layers, which remain relatively intact. In the spring, when the northward flow of air diminishes, the haze disperses and is carried to higher levels in the atmosphere and back to the mid latitudes. Knowing the components
and sources of Arctic haze can provide insight into the effects it has on
the ecology of the Arctic and on global climate, As a result, scientists
are calling for research into the environmental impacts of the haze and
for cooperative action among countries in the Northern Hemisphere to reduce
the amount of haze. In the meantime, humans are producing enough toxic
emissions to carry as far as 6215 miles to the North Pole and to produce
pollution levels there as great as those found in the medium sized industrial
cities of North America.
|
