Air Pollution (التلوث الهوائي)

Air pollution هو وجود أي مواد صلبه أو سائلة أو غازية بالهواء بكميات تؤدي إلى أضرار فسيولوجية واقتصادية وحيوية بالانسان والحيوان والنباتات

Atmospheric Chemistry Cycles and Residence Times Atmosphere composition mostly Nitrogen (76.6 %), Oxygen (23.1 %), and other gases (Argon, Ozone,Heleium, etc) Chemical materials cycle through the atmosphere as they do in other reservoirs Residence Times Influenced by amounts present in a given reservoir CO2 – 4 years O2 - 7 million years N2 – 44 million years

Figure 17.1 The Global carbon cycle

Cost of Air Pollution Air pollution is costly $40 billion – Worldwide annual expense of forest-product harvest reduction due to air pollution $16 billion annual U.S. expense (direct costs) Medical costs are enormous: Illness Medical treatment Absenteeism Loss of production

انواع الملوثات الهوائية ملوثات اساسية: وهي الناتجة عن حرق الوقود مثل الفحم الحجري والنفط والغاز الطبيعي حرقاً كاملاً. تشمل هذه الملوثات ثاني اكسيد الكربون,بخار الماء,ثاني اكسيد الكبريت,اكاسيد النيتروجين, إضافة إلى العناصر الثقيلة التي تكون بحالة غازية أو صلبة دقيقة مثل : الزرنيخ (As) والكادميوم (Cd) والرصاص (Pb) والزئبق Hg) ) ملوثات ثانوية: هي ناتجة من تفاعل الملوثات الأساسية للهواء مع بعضها بعضاً أو مع ملوثات أخرى أو مع الماء ، أو مع أشعة الشمس . تشمل هذه الملوثات الضباب الدخانى (Smog) والأوزون والمطر الحمضي

Types of Air Pollution Gaseous pollutants (الملوثات الغازية) CO and CO2 SO2 NO, NO2 Ozone and CFCs Particulates (الجسيمات العالقة) Soot سواد الدخان)) Smoke (الدخان) (from incomplete burning of oil and coal) Ash (from burning coal) (الرماد) Dust (released from industrial processes)(الغبار) Other solids release by burning From 35 million tons/year (mainly combustion) to 180 million tons/year (mostly industrial)

Figure 17.2 Principal sources of U.S. air pollutants, 1998

Figure 17.3 U.S. particulate emissions were controlled

Carbon Gases CO – carbon monoxide CO2 - carbon dioxide Not very abundant in the atmosphere but deadly Odorless, tasteless and invisible – toxic to animals Very short residence time but easily added to the atmosphere by common anthropogenic sources (automobiles) CO2 - carbon dioxide Essential for life of plants (photosynthesis) Product of plant respiration, combustion, and volcanic eruptions Short residence time and easily fluxes between oceans and atmosphere

Figure 17.1 The Global carbon cycle

Figure 17.4 a Emissions of carbon monoxide

Sulfur Gases More than 50 million tons of sulfur dioxide (SO2) are emitted worldwide each year mainly from coal combustion SO2 - sulfur dioxide forms acid rain very short residence time (days or hours) By product from combusting coal SO2 + H2O + ½ O2 = H2SO4 (sulfuric acid) and will lower the pH scale for rain Can contribute to acid rain causing lung and eye irritation Becomes a contributor to water pollution

Figure 17.4 b Emissions of sulfur dioxide

Nitrogen Gases and “Smog Ozone” Complex geochemistry oxygen and nitrogen are very abundant in the atmosphere high temperatures cause nitrogen and oxygen to form nitrogen oxide compounds 2NO2 + H2O + ½ O2 = 2HNO2 (nitric acid) NO2 + strong sun light will produce photochemical smog (الضباب الدخاني) NO2 can breakdown in sun light to NO and will react with common oxygen (O2) to form ozone (O3) Ozone inhibits photosynthesis in plants and can cause severe medical problems to people in urban areas where abundant automobiles are in operation

Nitrogen Gases and “Smog Ozone” http://www.melazerte.com/courses/A.Wong_FINAL%20Project/Chemistry_Photochemical_smog.htm

Figure 17.5 Nitrogen-gas emissions

Fig. 17.06 substandard and near-ground ozone

The Ozone Layer and Chlorofluorocarbons (CFCs) Ozone (O3) is a ‘chemically out of place pollutant’ In upper atmosphere (stratosphere) the ozone layer absorbs harmful ultraviolet radiation Ozone forms as O2 + ½ O2 = O3 At ground level it is very harmful to plants and animals A thick ozone layer is beneficial to life on earth Periodically, an ozone hole forms over either pole. This allows more ultra violet radiation to enter the lower atmosphere CFCs attack ozone and can destroy, or thin, the ozone layer CFCs build up their concentration in the upper atmosphere, have a residence time of about 100 years, and breakdown into various by-products including chlorine monoxide (ClO) One ClO can destroy many ozone molecules

Figure 17.7 Ozone layer

Figure 17.8 a

Figure 17.8 b

Figure 17.9

Figure 17.10

Figure 17.11

Figure 17.12

Figure 17.13

Figure 17.14

Particulate Pollutants Lead - once a serious pollutant Used in gasoline as an antiknock additive, tons of lead were released into the atmosphere by internal combustion engines Unleaded fuels have reduced lead in air pollution High doses of lead can cause brain damage, depression, apathy, and other psychological disorders

Figure 17.15 b

الملوثات و الاضرار الصحية الناتجة الضرر 1- أكاسيد الكبريت وأكاسيد النيتروجين - أمراض الرئة. - إلحاق الضرر بالحيوان والنبات. - تعمل علي تآكل المواد المستخدمة فى الأبنية. 2- الجسيمات العالقة - تسبب الأمراض الصدرية. 3- أول أكسيد الكربون - يؤثر علي الجهاز العصبي. - يحدث قصور في الدورة الدموية. 4- الرصاص - يسبب أمراض الكلي. - يؤثر علي الجهاز العصبي وخاصة فى الأطفال. 5- الضباب الداخلي

Acid Rain Acidity is reported on the pH scale. An acid solution has more Hydrogen-ions (H+) A basic solution would have fewer Acid rain has more acid than normal rain Certain gases in the atmosphere will complex with atmospheric water plus oxygen to form acids Acid rain is harmful to plants, health of rivers and lakes, and animals Acid rain causes increases in the build up of heavy metals (lead, zinc, selenium, copper, and aluminum) leached from rocks and soils Toxic levels are then found in our waterways, fish, and fish eaters

Figure 17.16

Figure 17.17

Regional Variations in Rainfall Acidity and Impacts Rain down wind of an industrial or populated areas have greater acidic conditions Generally, industrial areas have notably higher sulfur dioxide emissions than non-industrial areas Urban areas, with automobiles, generally have higher nitrogen oxide emissions than areas without autos Local geology can reduce the acidity of waterways that receive acid rain. Limestone can neutralize acidic water; granite can not

Figure 17.18

Air Pollution and Weather Thermal Inversion Pollutants released from ground sources generally are warmer than the surrounding air and tend to rise As an air mass these plumes will rise and cool In certain situations a cool air mass will have a warm air mass overlying it, it will trap the rising warm pollutant-bearing air mass; this condition is made worse by an air mass with stagnant conditions As more pollutants are dumped into the cooler air mass they will become concentrated below the warm air mass Eventually, the concentrations of pollutants may become very high and cause a health concern Local topography – mountains, basins, valleys, and local wind patterns may amplify the situation also

Figure 17.19 a

Figure 17.19 b

Figure 17.20

Figure 17.21 a

Figure 17.21 b

Air Pollution and Weather Air pollution can impact local weather Reduce visibility Reduce air quality Modify air temperature Produce acid rain Produce abnormal rain

Figure 17.22

Air Pollution Control Air Quality Standards – Clean Air Act (1970) Designed to protect public health, clear the visible pollution in the air, and prevent damage to crops Control Methods Trapping or scrubbing emissions conversion techniques that reduce the emission of harmful compounds to less harmful ones Automobile Emissions – strong legislation creates the Environmental Protection Agency (EPA) Goal to reduce automobile emissions Limited success achieved by requiring the use of catalytic converters in new cars and increased fuel economy standards for all new cars Cost and Effects – it has increased abatement and control cost while limited areas of success have occurred

Fig. 17.23

Figures 17.24 a and b

وسائل مكافحة تلوث الهواء 1 - استخدام المداخن العالية لتوزيع الملوثات على حيز اكبر من الهواء . 2- استخدام وسائل الترشيح وعرف الترسيب لازالة الجسيمات من المداخن او الادخنة والغازات من مواسير العادم. 3- حرق الملوثات الغازية مثل جهاز الشعلة بمعامل البترول لحرق الغازات الكبرتيه السامة. 4- استخدام وسائل الامتصاص مثل اسطح الكربون النشط او الامونيا او السليكا لامتصاص الملوثات الغازية . 5- غسل الملوثات كالامونيا بالمادة وقليل من الاحماض او تحويلها الى مركبات نافعة بالاكسدة مثلا. 6- استخدام الوقود الاقل تلويثا (يخلو من الكبريت والرصاص ) كالغاز الطبيعى والكحوليات والطاقة الشمسية والنووية والرياح . 7- تعديل خطوات وعمليات الصناعة واستخدام مواد وسيطة واقل تلويثا وتحسين المحركات . 8 - التخطيط السليم عند إنشاء المصانع وذلك للبعد عن المناطق السكنية وخاصة المزدحمة بالسكان وذلك لوقاية المجتمعات . 9 – تحديد مرور السيارات ومنع السيارات ذات العادم الزائد وذلك لنمو عالم افضل خالي من التلوث والأمراض المزمنة.