The ecosystem pollution

The pollution of ecosystem is divided into: 1- Air pollution 2- Aquatic pollution 3-Terrestrial pollution

Air Pollution

Air pollution Sources of air pollution Pollutants are discharged into the atmosphere in gaseous state from 1.Combustion of fuel. 2. Open fires. 3.Industrial processing of metals. 4.Gasoline synthetic chemicals. 5.The domestic energy supply.

Types of pollutants 1.Carbon monoxide (Co) and carbon dioxide (Co2). 2.Sulfur dioxide (SO2). 3.Oxides of nitrogen (NO2). 4.Volatile organic compounds such as benzene, and toluene. 5.Polycyclic aromatic hydrocarbons such as benzo- pyrene, hydrogen fluoride and chlorofluorocarbons. 6.Metals, non metals and other suspended particulate matter.

Natural air pollution: volcanic activity

Criteria of Air Pollutants

Carbon monoxide (CO) It produced from the incomplete combustion of organic materials (particularly fossil fuels). Exposure to this gas can be fatal to animals or humans.

Carbon monoxide It is highly toxic as it has high affinity for haemoglobin (Hb), thus displaces Hb-bound oxygen and increases carboxy-haemoglobin (Co-Hb) concentration with the current decrease in oxygen- carrying capacity of blood and thus causing dyspnoea. Affinity of Hb for Co is 220 times greater than oxygen; therefore, Co is dangerous even at very low concentrations.

Sulfur oxides It produced from sulfur- containing fossil fuels primarily coal (used for the generation of electricity and industry).

Sulfur dioxide It is a mild respiratory irritant and predominantly acts on the upper respiratory tract and causes bronchoconstriction. It increase mucous secretion due to proliferation of goblet cells and finally produces bronchitis. It also impairs macrophages-dependant host defense mechanism.

Sulfur dioxide when comes in contact with oxygen or water in air in the presence of moisture is oxidized to sulfur trioxide, sulfuric acid. Sulfuric acid comes on the earth in the form of acid rain. Sulfuric acid is also respiratory system irritant. It induces bronchoconstriction by causing hyperplasia of airway mucousecretory cells and in chronic and prolonged exposure, it induces bronchitis.

Nitrous oxides (e.g., Nitrogen dioxide) It arise from combustion that releases O2 which combines with N from the air. These also are the result of autos (~ 50%) and electrical utility and industrial combustion (most of the rest). These gases are components of smog, acid deposition, and also are components of harmful secondary pollutants.

Nitrogen oxides Nitrogen dioxide is a deep lung irritant and it penetrates to alveolar capillary membranes where it converted to nitric acid and produce lung oedema. This pollutant is of particular risk to farmers because very high amounts of No2 are liberated from ensilage. Silo filler's disease due to NO2 and CO poisoning is well documented.

Hydrocarbons Different hydrocarbons formed are low molecular weigh aliphatic, olefinic and aromatic compounds. The olefinic and aromatic hydrocarbon vapors are more irritating to mucous membrane and systemic injury occurs on inhalation of aromatic vapors. The hydrocarbon air pollutants promote the formation of photochemical smog. Some polycyclic aromatic hydrocarbons (PAHs) are potent carcinogens and mutagens.

Particulate materials It include both organic or inorganic particulate materials of different diameters, all metals are found in some concentration in the atmospheric particles. The most common metal released with oils and coal combustion are lead, mercury, copper, manganese, chromium, cadmium, beryllium, iron, magnesium, nickel.

Particulates (small pieces of solids e.g., ash, asbestos, dust etc.) Some are carcinogenic, others trap diverse “nasties” on their surfaces. London’s killer smog of 1952 (responsible for 4,000 deaths over 4 days) was partially the result of this type of pollutant (also from SO2).

Lead It was a problem prior to the change in gasoline (leaded to unleaded). (mental retardation). Compounds containing lead where added to gasoline and then released into the atmosphere where they could enter the food chain, bioaccumulate, and then cause problems especially in children (mental retardation). Currently lead is at a low level in the U. S. air, but other countries continue to use leaded gasoline.