අම්ල වැස්ස is a වැස්ස or any other form of අවක්ෂේපනය that is unusually ආම්ලික, i.e. elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals, and infrastructure through the process of wet deposition. Acid rain is caused by emissions of compounds of ammonium, carbon, nitrogen, and sulfur which react with the water molecules in the atmosphere to produce acids. Governments have made efforts since the 1970s to reduce the production of sulfur dioxide into the atmosphere with positive results. However, it can also be caused naturally by the splitting of nitrogen compounds by the energy produced by lightning strikes, or the release of sulfur dioxide into the atmosphere by volcano eruptions.
"අම්ල වැස්ස" is a popular term referring to the deposition of wet (වැසි, හිම, sleet, මීදුම, cloudwater, and dew) and dry (acidifying particles and gases) acidic components.
තෙත ( නිධිසාධනය )[සංස්කරණය]
Wet deposition of acids occurs when any form of precipitation (rain, snow, etc.) removes acids from the වායුගෝලය and delivers it to the Earth's surface. This can result from the deposition of acids produced in the raindrops (see aqueous phase chemistry above) or by the precipitation removing the acids either in clouds or below clouds. Wet removal of both gases and aerosols are both of වැදගත්කම for wet deposition.
Acid deposition also occurs via dry deposition in the absence of precipitation. This can be responsible for as much as 20 to 60% of total acid deposition. This occurs when particles and gases stick to the ground, plants or other surfaces.
වළක්වා ගැනීමේ ක්රම[සංස්කරණය]
In the United States, many coal-burning power plants use Flue gas desulfurization (FGD) to remove sulfur-containing gases from their stack gases. An example of FGD is the wet scrubber which is commonly used in the U.S. and many other countries. A wet scrubber is basically a reaction tower equipped with a fan that extracts hot smoke stack gases from a power plant into the tower. Lime or limestone in slurry form is also injected into the tower to mix with the stack gases and combine with the sulfur dioxide present. The calcium carbonate of the limestone produces pH-neutral calcium sulfate that is physically removed from the scrubber. That is, the scrubber turns sulfur pollution into industrial sulfates.
In some areas the sulfates are sold to chemical companies as gypsum when the purity of calcium sulfate is high. In others, they are placed in landfill. However, the effects of acid rain can last for generations, as the effects of pH level change can stimulate the continued leaching of undesirable chemicals into otherwise pristine water sources, killing off vulnerable insect and fish species and blocking efforts to restore native life.
Automobile emissions control reduces emissions of nitrogen oxides from motor vehicles.
In this regulatory scheme, every current polluting facility is given or may purchase on an open market an emissions allowance for each unit of a designated pollutant it emits. Operators can then install pollution control equipment, and sell portions of their emissions allowances they no longer need for their own operations, thereby recovering some of the capital cost of their investment in such equipment. The intention is to give operators economic incentives to install pollution controls.
The first emissions trading market was established in the United States by enactment of the Clean Air Act Amendments of 1990. The overall goal of the Acid Rain Program established by the Act is to achieve significant environmental and public health benefits through reductions in emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx), the primary causes of acid rain. To achieve this goal at the lowest cost to society, the program employs both regulatory and market based approaches for controlling air pollution.
- UK National Air Quality Archive: Air Pollution Glossary
- Clean Air Act Amendments of 1990, 42 U.S. Code 7651
- John McCormick, Acid Earth: The Global Threat of Acid Pollution (London: Earthscan, 1989) ISBN 978-1-85383-033-4
- Likens, G. E., R. F. Wright, J. N. Galloway and T. J. Butler. 1979. Acid rain. Sci. Amer. 241(4):43-51.
- Weathers, K. C. and G. E. Likens. 2006. Acid rain. pp. 1549–1561. In: W. N. Rom (ed.). Environmental and Occupational Medicine. Lippincott-Raven Publ., Philadelphia. Fourth Edition.
- National Acid Precipitation Assessment Program Report - a 98-page report to Congress
- Acid rain for schools
- Acid rain for schools - Hubbard Brook
- U.S. Environmental Protection Agency - New England Acid Rain Program (superficial)
- Acid Rain (more depth than ref. above)
- U.S. Geological Survey - What is acid rain?
- Acid rain analysis - freeware for simulation and evaluation of titration curves and pH calculations
- CBC Digital Archives – Acid Rain: Pollution and Politics
- Larssen, Thorjørn et al. “Acid Rain in China”. Environmental Science and Technology, 40:2, 2006, pp 418-425.
- Acid Rain: A Continuing National Tragedy - a report from The Adirondack Council on acid rain in the Adirondack region
- Assortment of Summaries on Acid Rain
- Acid rain linked to decline of the wood thrush, a songbird of the Eastern Forest
- Trouble in the Forest, a 1988 documentary hosted by David Suzuki
- What Happens to Acid Rain?