Air, Water & Soil Pollution Lecture 9 PDF

Air, Water & Soil Pollution Lecture 9 5/4/2020 by Dr. Ghada Samy  1. Air pollution Types of air pollutants Particulate matter...

Air, Water & Soil Pollution Lecture 9 5/4/2020 by Dr. Ghada Samy  1. Air pollution Types of air pollutants Particulate matter Gaseous pollutants Sulfur Aerosol oxides Hydrocarbons Smoke Dust Fumes CO2 H2S Mist Greenhouse effect Nitrogen Coal dust oxides CO Ash Zinc oxides Sawdust Lead oxides Carboxyhemoglobin O3 Cement dust Acid rain Grain dust H2SO4 Incomplete mist combustion of Tropospheric Stratospheric fossil fuels "bad O3" "good O3" 1  1. Air pollution Ozone (O3): Highly irritant & oxidizing gas, formed by photochemical action of UV light on NO2 in smog Tropospheric ozone: Occurs from 0 to 10 miles above earth’s surface, & is harmful. Stratospheric ozone: Located 30 miles above earth’s surface, responsible for filtering out incoming UV radiation & thus is beneficial. The ↓ in stratospheric ozone layer will ↑ amount of UV radiation reaching earth’s surface & cause ↑ in skin cancer. Chlorofluorocarbons (CFCs) may contribute to damage to stratospheric ozone. Fluorosis (fluoride toxicity): Fluoride emissions from industries producing phosphate fertilizers have damaged cattle throughout the world. Farm animals are susceptible to fluorosis, which is characterized by mottled & soft teeth, osterofluoritic bone lesions, which lead to lameness, & eventually, death. Greenhouse effect: CO2 absorbs heat energy strongly & retards cooling of earth. Theoretically, an ↑ in CO2 levels would result in a global ↑ in air temperatures. Acidic deposition (acid rain): (Acid rain has a pH ˂ 4, Normal uncontaminated rain → pH=5.6) Is caused by emissions of sulfur dioxide & nitrogen oxides into air, which mix & react with H2O & O2 in atmosphere to form acid rain. Nitrogen oxides can also be produced naturally by lightning strikes, & sulfur dioxide is also produced by volcanic eruptions. Acid rain has adverse impacts on forests, freshwaters & soils, killing insect & aquatic life-forms. Many lakes in North America have become so acidic that fish are no longer able to live in them. Acid rain can leach toxic metals, such as aluminum from soil, ↓ tree growth in forests, causes corrosion of steel structures, such as: bridges 2  Sources of air pollutants Indoor pollutants Natural pollutants Anthropogenic pollutants Heating & cooking Pesticides Tobacco smoking Gases Microbes from people, animals Combustion sources Industrial processes Mining , drilling Erupting volcano Dust storms Forest fires Ocean Nitrogen oxides Gases Particulate matter Smoke Aerosols in CO Acids Gases Metals Hydrocarbons form of salt fly Ash CO Smoke Methane Nitrogen oxides Sulfur Ammonia Zinc Sulfur dioxide Ash CO2 Chlorine Lead H2S Copper 3  Point source emissions e.g. Smelters Arsenic Acid gases Lead O3 Molybdenum SO2 Fluoride CO2 Methane CFCs Sulfur dioxide Nitrous oxide Nitrogen oxides O3 4  2. Water & Soil pollution Nitrates & phosphates Oils & Dioxin petroleum Radioactive Volatile organic contamination compounds Water & Soil Pollutants Metals Pesticides Low Mwt Acids chlorinated hydrocarbons 5  Nitrates & Phosphates Source of nitrate contamination: fertilizers & discharge from sewage treatment plant Source of Phosphate contamination: fertilizers & detergents Algal blooms: Is accumulation of algae in water, & is often recognized by discoloration in water from their pigments. It is caused by ↑ in nitrates & phosphates, particularly phosphate in lakes & very slow moving rivers Algal blooms ↓ light penetration & restrict atmospheric re-oxygenation of water. When dense algal growth dies, the subsequent biodegradation, result in anaerobic condition & death of many aquatic organisms ↑ phosphate concentration & algal blooms aren’t problem in moving streams, because such is continually flushed out & algae don’t accumulate Blue-baby disease: Nitrates in drinking water can cause methemoglobinemia: Ingested nitrates can be converted to nitrites by intestinal bacteria. Nitrites combine with haemoglobin to form methemoglobin, thus ↓ oxygen- carrying capacity of blood & result in anaemia or "blue-baby" disease, as it occurs only in infants. Older children & adults are able to detoxify methemoglobin by methemoglobin reductase. In infant, this enzyme isn’t fully functional. Agent orange Is a herbicide & a defoliant, widely used by U.S. military during Vietnam war, & caused major health & environmental problems, as: various kinds of cancer in exposed veterans, birth defects of children of veterans & forest were defoliated. Agent orange is a mixture of two herbicides, contains traces of dioxin (mainly TCDD, the most toxic in chlorophenoxy herbicides, formed during manufacturing process & is a proven carcinogen in laboratory animals) 6