PBH Final Mahi

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  • 8/3/2019 PBH Final Mahi


    Public Health AssignmentOn Water Pollution and Global Warming

    Submitted to: Dr. Maleeha Azeem (Mea)

    Submitted By: Mushfiqur Rahman

    Id: 1110685030

    Section: 7

  • 8/3/2019 PBH Final Mahi






  • 8/3/2019 PBH Final Mahi



    What Is Water Pollution?

    Water pollution refers to degradation of water quality. It is a large set of adverse effects upon waterbodies such as lakes, rivers, oceans, and groundwater caused by human activities. Water pollution can

    be defined as "the presence of a substance in the environment that because of its chemical composition

    or quantity prevents the functioning of natural processes and produces undesirable environmental and

    health effects

    Water pollution can be defined in many ways. Usually, it means one or more substances havebuilt up in water to such an extent that they cause problems for animals or people. This could

    affect the health of all the plants, animals, and humans whose lives depend on the river.

    Dozens of times a day those of us who live in the industrialized nations of the world enjoy ablessing denied to 75 percent of the world population: abundant supplies of clean water. For

    centuries water has been used as a dumping ground for human sewage and industrial wastes.

    Added to them are the materials leached out and transported from land by water percolating

    through the soil and running off its surface to aquatic ecosystems. Thus the term water

    pollution refers to "Water contamination by a variety of chemical substances or

    eutrophication caused by several nutrients and fertilizers (Southwick, 1976)".

    Water is typically referred to as polluted when it is impaired by anthropogenic contaminantsand either does not support a human use or undergoes a marked shift in its ability to support its

    constituent biotic communities.

    U.S. Department of Health Education and Welfare defines water pollution as "The adding towater ofany substance, or the changing ofwater's physical and chemical characteristics

    in any way which interferes with its use oflegitimate purposes".

    Water is typically referred to as polluted when it is impaired by anthropogenic contaminantsand either does not support a human use, such as drinking water, and/or undergoes a marked

    shift in its ability to support its constituent biotic communities, such as fish. Natural

    phenomena such as volcanoes, algae blooms, storms, and earthquakes also cause major

    changes in water quality and the ecological status of water.

  • 8/3/2019 PBH Final Mahi


    The sources of Water Pollution:

    There two major kinds of pollution sources:

    - Point sources

    - Non-point sources

    Point sources:

    Point source water pollution refers to contaminants that enter a waterway from a single, identifiable

    source, such as a pipe or ditch. Examples of sources in this category include discharges from a sewage

    treatment plant, a factory, or a city storm drain. The U.S. Clean Water Act (CWA) defines point

    source for regulatory enforcement purposes. The CWA definition of point source was amended in

    1987 to include municipal storm sewer systems, as well as industrial storm water, such as from

    construction sites.

    Nonpoint sources:

    Nonpoint source pollution refers to diffuse contamination that does not originate from a single

    discrete source. NPS pollution is often the cumulative effect of small amounts of contaminants

    gathered from a large area. A common example is the leaching out of nitrogen compounds from

    fertilized agricultural lands. Nutrient runoffin storm water from "sheet flow" over an agriculturalfield

    or a forest is also cited as examples of NPS pollution.

    Contaminated storm water washed off of parking lots, roads and highways, called urban runoff, is

    sometimes included under the category of NPS pollution. However, this runoff is typically channeled

    into storm drain systems and discharged through pipes to local surface waters, and is a point source.

    However where such water is not channeled and drains directly to ground it is a non-point source.

    The Common Pollutants:

    Infectious Agents

    These are disease causing agents or pathogens, e.g. bacteria, viruses, protozoa, parasites. These come

    from raw sewage and animal waste. These are measured by the amount of Coliform bacteria present.

  • 8/3/2019 PBH Final Mahi


    Oxygen-demanding wastes

    Sewage, animal manure or biodegradable organic wastes, which can be decomposed by aerobic

    bacteria which cause a reduction in dissolved oxygen (DO) results in suffocating for oxygen-

    consuming organisms (fish). These are measured by biological oxygen demand (BOD).

    Water soluble Inorganic chemicals

    Water-soluble inorganic chemicals, includes acids, salts, and metals. Make water unfit to consume and

    use for irrigation. Also can harm organisms and cause material corrosion.

    Organic chemicals


    Disinfection by-products found in chemically disinfected drinking water, such as chloroform Food processing waste, which can include oxygen-demanding substances, fats and grease Insecticides and herbicides, a huge range oforgan halides and other chemical compounds Petroleum hydrocarbons, including fuels (gasoline, diesel fuel, jet fuels, and fuel oil) and

    lubricants (motor oil), and fuel combustion byproducts, from storm water runoff.

    Tree and bush debris from logging operations Volatile organic compounds (VOCs), such as industrial solvents, from improper storage. Chlorinated solvents, which are dense non-aqueous phase liquids (DNAPLs), may fall to the

    bottom of reservoirs, since they don't mix well with water and are denser.

    o Polychlorinated biphenyl (PCBs)o Trichloroethylene

    Perchlorate Various chemical compounds found in personal hygiene and cosmetic products

    Inorganic water pollutants include:

    Acidity caused by industrial discharges (especially sulfur dioxide from power plants) Ammonia from food processing waste Chemical waste as industrial by-products Fertilizers containing nutrients--nitrates and phosphates--which are found in storm water runoff

    from agriculture, as well as commercial and residential use