الأثر البيئي لاستخدام الفحم

موقع لتعدين الفحم في بيهار، الهند.
A mountaintop removal mining operation in the United States

الأثر البيئي لاستخدام الفحم environmental impact of the coal industry، تشمل النظر في قضايا مثل استخدام الأراضي، ادارة النفايات، وتلوث الهواء والمياه الذي يسببه تعدين الفحم، معالجة واستخدام منتجاته. بالإضافة لتلولث الغلاف الجوي، فالنفايات الصلبة الناتجة من مئات الأطنان من منتجات حرق الفحم سنوياً، وشتمل الرماد المتاطير،[1] الرماد المتراكم، وإزالة الكبريت من غاز المداحن، والذي يحتوي على الزئبق، اليورانيوم، الثوريوم، الزرنيخ، ومعادن ثقيلة أخرى.

يتسبب حرق الفحم في آثار صحية خطيرة.[2][3] حسب تقرير أصدرته منظمة الصحة العالمية في 2008 والجماعات المعنية بالبيئية في 2004، فالتلوث بجزيئات الفحم يتسبب في تقصير عمر حوالي 1.000.000 شخص سنوياً في العالم، ويشمل ما يقارب من حياة 24.000 شخص في الولايات المتحدة.[4][5] يؤدي تعدين الفحم إلى آثار صحية بيئية سلبية أخرى كبيرة، مثل تدفق الماء الملوث من التعدين بإزالة قمم الجبال.

تاريخياً، كان لتعدين الفحم نشاط بالغ الخطورة وقائمة كوارث تعدين الفحم التاريخية طويلة. مخاطر تعدين الفحم في المناجم تشمل الاختناق، التسمم بالغاز، انهيار المناجم، وانفجار المركبات.

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ادارة المياه

يتطلب التعدين السطحي كميات كبيرة من المياه من أجل محطات إعداد الفحم وإخماد الأتربة. ولتلبية هذه الحاجة، تستفيد المناجم من مصادر المياه السطحية والجوفية الموجودة في المناطق الزراعية والسكنية القريبة منها (وتزيلها)، الأمر الذي يقلل من إنتاجية هذه العمليات أو يوقفها تمامًا. ونادرًا ما تعود هذه المصادر المائية (بمجرد انفصالها عن بيئتها الطبيعية) بعد عمليات التعدين، مما يؤدي إلى تدهور دائم في الإنتاجية الزراعية. وللتعدين تحت الأرض تأثير مشابه (لكنه أقل حدة)، بسبب انخفاض الحاجة للمياه اللازمة لإخماد الأتربة؛ لكنه يظل بحاجة لكمية مياه كافية لغسل الفحم.


ادارة استخدام الأراضي

الآثار على الأراضي والجوار

ادارة النفايات

Aerial photo of pollution caused by leaking sludge storage pond
Aerial photograph of Kingston Fossil Plant coal fly ash slurry spill site taken the day after the event (December 23, 2008)


آثار على الحياة البرية

تلوث الهواء

انبعاثات الهواء

انظر أيضاً: Coal seam fire

Coal and coal waste products (including fly ash, bottom ash and boiler slag) releases approximately 20 toxic-release chemicals, including arsenic, lead, mercury, nickel, vanadium, beryllium, cadmium, barium, chromium, copper, molybdenum, zinc, selenium and radium, which are dangerous if released into the environment. While these substances are trace impurities, enough coal is burned that significant amounts of these substances are released.[6]

During combustion, the reaction between coal and the air produces oxides of carbon, including carbon dioxide (CO2, an important greenhouse gas), oxides of sulfur (mainly sulfur dioxide) (SO2), and various oxides of nitrogen (NOx). Because of the hydrogenous and nitrogenous components of coal, hydrides and nitrides of carbon and sulfur are also produced during the combustion of coal in air. These include hydrogen cyanide (HCN), sulfur nitrate (SNO3) and other toxic substances.

The wet cooling towers used in coal-fired power stations, etc. emit drift and fog which are also environmental concern. The drift from the cooling towers is containing Respirable suspended particulate matter. In case of cooling towers with sea water makeup, sodium salts are deposited on nearby lands which would convert the land into alkali soil by reducing the fertility of vegetative lands and also cause corrosion of nearby structures.

Fires sometimes occur in coal beds underground. When coal beds are exposed, the fire risk is increased. Weathered coal can also increase ground temperatures if it is left on the surface. Almost all fires in solid coal are ignited by surface fires caused by people or lightning. Spontaneous combustion is caused when coal oxidizes and airflow is insufficient to dissipate heat; this more commonly occurs in stockpiles and waste piles, rarely in bedded coal underground. Where coal fires occur, there is attendant air pollution from emission of smoke and noxious fumes into the atmosphere. Coal seam fires may burn underground for decades, threatening destruction of forests, homes, roadways and other valuable infrastructure. The best-known coal-seam fire may be the one which led to the permanent evacuation of Centralia, Pennsylvania, United States.[7]

Approximately 75 Tg/S per year of Sulfur Dioxide (SO2) is released from burning coal. After release, the Sulfur Dioxide is oxidized to gaseous H2SO2 which scatters solar radiation, hence their increase in the atmosphere exerts a cooling effect on climate that masks some of the warming caused by increased greenhouse gases. Release of SO2 also contributes to the widespread acidification of ecosystems.[8]

انبعاثات الزئبق

Mercury emission from coal burning are concentrated as they work their way up the food chain and are converted into methylmercury, a toxic compound which harms both wildlife and people who consume freshwater fish.[9][10][11][11][12] Coal burning is a key source of methylmercury in the environment.[13] "Power plants... are responsible for half of... the mercury emissions in the United States."[14]

In New York State winds bring mercury from the coal-fired power plants of the Midwest, contaminating the waters of the Catskill Mountains. The mercury is consumed by worms, which are eaten by fish, which are eaten by birds (including bald eagles). As of 2008, mercury levels in bald eagles in the Catskills had reached new heights.[15] "People are exposed to methylmercury almost entirely by eating contaminated fish and wildlife that are at the top of aquatic food chains."[16] Ocean fish account for the majority of human exposure to methylmercury; the full range of sources of methylmercury in ocean fish is not well understood.[17]

The United States Environmental Protection Agency has proposed the Mercury and Air Toxics Standards (MATS) regulations,[18] which require all coal plants use the technology which is available to substantially reduce mercury emissions.[19] "Today, more than half of all coal-fired power plants already deploy pollution control technologies that will help them meet these achievable standards. Once final, these standards will level the playing field by ensuring the remaining plants – about 40 percent of all coal-fired power plants - take similar steps to decrease dangerous pollutants."[14]

الوفيات السنوية الزائدة

In 2008 the World Health Organization (WHO) and other organizations calculated that coal particulates pollution cause approximately one million deaths annually across the world,[5] which is approximately one third of all premature deaths related to all air pollution sources.[20]

Pollutants emitted by burning coal include fine particulates (PM2.5) and ground level ozone. Every year, the burning of coal without the use of available pollution control technology causes thousands of preventable deaths in the United States. A study commissioned by the Maryland nurses association in 2006 found that emissions from just six of Maryland's coal-burning plants caused 700 deaths per year nationwide, including 100 in Maryland.[21] Since installation of pollution abatement equipment on one of these six, the Brandon Shores plant, now "produces 90 percent less nitrogen oxide, an ingredient of smog; 95 percent less sulfur, which causes acid rain; and vastly lower fractions of other pollutants."[21]

According to a report published in 2004, coal-fired power plants shorten nearly 24,000 lives a year in the United States (2,800 from lung cancer).[4] In الولايات المتحدة alone, the United States Environmental Protection Agency (EPA) estimates that a range of 13,000 to 34,000 preventable premature deaths will be avoided by the reductions in PM2.5 and ozone expected by the end of the several-years time needed to complete implementation of the coal plant cleanup provisions of the Final Cross-State Air Pollution Rule (CSAPR).[22]

In addition to preventing avoidable premature deaths, the Final Cross-State rule is estimated to prevent 15,000 additional (non-fatal) heart attacks, 19,000 attacks of acute bronchitis; 420,000 upper and lower respiratory symptoms, 400,000 aggravated asthma attacks; and 19,000 hospital and ER trips (e.g., for asthma attacks triggered by soot from coal burning). By reducing the health detriments that arise from burning coal without using available pollution controls, implementation of the Final Cross-State Air Pollution Rule is expected to reduce days when people must miss work or school by 1.8 million.[23][24]

The Cross-State Air Pollution Rule requires significant reductions in sulfur dioxide (SO2) and nitrogen oxide (NO) emissions that cross state lines. These pollutants react in the atmosphere to form fine particles and ground-level ozone and are transported long distances, making it difficult for other states to achieve healthy levels of pollution control. The benefits of the emission reductions expected from EPA's recently proposed Mercury and Air Toxics Standards (MATS) are not included in the above estimated emission reductions from the Cross-State Air Pollution Rule; once the Mercury and Air Toxics Standards[19] are implemented, death and disease from coal burning are likely to be reduced even further, both directly by reducing mercury poisoning, and by reducing sulfur dioxide emissions.

التكلفة الاقتصادية

A major EU funded research study known as ExternE, or Externalities of Energy, undertaken over the period of 1995 to 2005 found that the cost of producing electricity from coal would double over its present value, if external costs such as damage to the environment and to human health, from the airborne particulate matter, nitrogen oxides, chromium VI and arsenic emissions produced by coal, were taken into account. It was estimated in the study that external, downstream, fossil fuel costs amount up to 1–2% of the EU’s entire Gross Domestic Product (GDP), with coal the main fossil fuel accountable for this, and this was before the external cost of global warming from these sources was even included.[25] The study also found that the environmental and health costs of coal alone were €0.06/kWh, or 6 cents/kWh, with the energy sources of the lowest external costs associated with them being nuclear power €0.0019/kWh, and wind power at €0.0009/kWh.[26]

High rates of motherboard failures in China and India appear to be due to "sulfurous air pollution produced by coal that’s burned to generate electricity. It corrodes the copper circuitry," according to Intel researchers.[27]

انبعاثات الغازات الدفيئة

The combustion of coal is the largest contributor to the human-made increase of CO2 in the atmosphere.[28] Electric generation using coal burning produces approximately twice the greenhouse gasses per kilowatt compared to generation using natural gas.[29]

Coal mining produces methane, a potent greenhouse gas. Methane is the naturally occurring product of the decay of organic matter as coal deposits are formed with increasing depths of burial, rising temperatures, and rising pressure over geological time. A portion of the methane produced is absorbed by the coal and later released from the coal seam (and surrounding disturbed strata) during the mining process.[30] Methane accounts for 10.5 percent of greenhouse-gas emissions created through human activity.[31] According to the Intergovernmental Panel on Climate Change, methane has a global warming potential 21 times greater than that of carbon dioxide over a 100-year timeline. The process of mining can release pockets of methane. These gases may pose a threat to coal miners, as well as a source of air pollution. This is due to the relaxation of pressure and fracturing of the strata during mining activity, which gives rise to safety concerns for the coal miners if not managed properly. The buildup of pressure in the strata can lead to explosions during (or after) the mining process if prevention methods, such as "methane draining", are not taken.[30]

In 2008 James E. Hansen and Pushker Kharecha published a peer-reviewed scientific study analyzing the effect of a coal phase-out on atmospheric CO2 levels. Their baseline mitigation scenario was a phaseout of global coal emissions by 2050. Under the Business as Usual scenario, atmospheric CO2 peaks at 563 parts per million (ppm) in the year 2100. Under the four coal phase-out scenarios, atmospheric CO2 peaks at 422–446 ppm between 2045 and 2060 and declines thereafter.[32]

التعرض للإشعاع

Coal also contains low levels of uranium, thorium, and other naturally occurring radioactive isotopes whose release into the environment may lead to radioactive contamination.[6][33] Coal plants emit radiation in the form of radioactive fly ash which is inhaled and ingested by neighbours, and incorporated into crops. A 1978 paper from Oak Ridge National Laboratory estimated that coal-fired power plants of that time may contribute a whole-body committed dose of 19 µSv/yr to their immediate neighbours in a 500 m radius.[34] The United Nations Scientific Committee on the Effects of Atomic Radiation's 1988 report estimated the committed dose 1 km away to be 20 µSv/yr for older plants or 1µSv/yr for newer plants with improved fly ash capture, but was unable to confirm these numbers by test.[35] A single PWR spent fuel bundle, after 10 years cooldown, with no shielding, emits 2.3 MSv/yr, a trillion times more than coal.[36] However, if we exclude contained waste and ignore unintentional releases from nuclear plants, coal-plants carry more radioactive wastes into the environment than nuclear plants producing the same amount of energy. Plant-emitted radiation carried by coal-derived fly ash delivers 100 times more radiation to the surrounding environment than does the normal operation of a similarly productive nuclear plant.[37] This comparison does not consider the rest of the fuel cycle, i.e., coal and uranium mining and refining and waste disposal.

أخطار على المعادن

The Farmington coal mine disaster kills 78. West Virginia, US, 1968.

Build-ups of a hazardous gas are known as damps, possibly from the German word "Dampf" which means steam or vapor:


انظر أيضاً

المصادر

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  3. ^ "Environmental impacts of coal power: air pollution". Union of Concerned Scientists. Retrieved 2012-03-09. 
  4. ^ أ ب "Deadly Power Plants? Study Fuels Debate". MSNBC. 2004-06-09. Retrieved 2012-03-06. 
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  6. ^ أ ب Gabbard, Alex (2008-02-05). "Coal Combustion: Nuclear Resource or Danger". Oak Ridge National Laboratory. Retrieved 2008-10-22. 
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  10. ^ NOAA: Atmospheric Mercury Modeling http://www.arl.noaa.gov/Mercury_modeling.php
  11. ^ أ ب DePalma, Anthony. Mercury’s Harmful Reach Has Grown, Study Suggests, The New York Times New York edition, January 24, 2012, p. D3. Published online January 23, 2012, retrieved January 25, 2012.
  12. ^ Brigham ME, Krabbenhoft DP, Hamilton PA (2003). "Mercury in stream ecosystems—new studies initiated by the U.S. Geological Survey". U.S. Geological Survey. Retrieved 2008-01-31. 
  13. ^ Atmospheric Mercury Measurements, NOAA
  14. ^ أ ب EPA Issues First National Standards for Mercury Pollution from Power Plants: Historic ‘mercury and air toxics standards’ meet 20-year-old requirement to cut dangerous smokestack emissions, EPA, Release Date: 12/21/2011, Contact Information (press only): Enesta Jones.
  15. ^ Anthony De Palma,"Bald Eagles in Catskills Show Increasing Mercury New York Times, November 24, 2008.
  16. ^ Fact Sheet 146-00 : Mercury in the Environment, U.S. Geological Survey, October 2000.
  17. ^ Jaffe E (2007-09-27). "Mystery at sea". Smithsonian.com. Archived from the original on 2008-01-17. Retrieved 2008-01-31. 
  18. ^ Mercury and Air Toxics Standards (MATS)
  19. ^ أ ب EPA: Mercury and Air Toxics Standards (MATS)
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  22. ^ The Clean Air Task Force. 2010.
  23. ^ Final Cross-State Air Pollution Rule
  24. ^ Cross-State Air Pollution Rule (CSAPR)
  25. ^ New research reveals the real costs of electricity in Europe
  26. ^ ExternE-Pol, External costs of current and advanced electricity systems, associated with emissions from the operation of power plants and with the rest of the energy chain, final technical report. See figure 9, 9b and figure 11
  27. ^ "Scientists studying pollution damage to computers". Missoulian. 2013-10-27. Retrieved 2013-10-27. 
  28. ^ James Hansen (2007). "Testimony of James E. Hansen at Iowa Utilities Board" (PDF). Columbia University. Retrieved 2008-10-22. 
  29. ^ "Environmental impacts of coal power: air pollution". Union of Concerned Scientists. 
  30. ^ أ ب "Methane Associated with Coal Seams". The Coal Authority. October 2007. Retrieved 2008-10-22. [dead link]
  31. ^ "Where Greenhouse Gases Come From — Energy Explained, Your Guide To Understanding Energy". Energy Information Administration, US Department of Energy. 2010-10-13. Retrieved 2010-02-19. 
  32. ^ Kharecha P.A.; Hansen J.E. (2008). "Implications of "peak oil" for atmospheric CO2 and climate". Global Biogeochem. Cycles. 22: GB3012. arXiv:0704.2782Freely accessible. Bibcode:2008GBioC..22.3012K. doi:10.1029/2007GB003142. 
  33. ^ "Radioactive Elements in Coal and Fly Ash, USGS Factsheet 163-97". Retrieved September 9, 2005. 
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  35. ^ United Nations Scientific Committee on the Effects of Atomic Radiation (1988). "Annex A". Sources, Effects and Risks of Ionizing Radiation. New York: United Nations. p. 83. ISBN 92-1-142143-8. Retrieved 16 November 2012. 
  36. ^ خطأ لوا في وحدة:Citation/CS1 على السطر 3565: bad argument #1 to 'pairs' (table expected, got nil).
  37. ^ Hvistendahl, Mara. "Coal Ash Is More Radioactive than Nuclear Waste: Scientific American", Scientific American, Nature America, Inc., 13 Dec. 2007. Web. 18 Mar. 2011.

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