AGEN 2363.  Chpt. 17 notes:  Water Quality and Pollution.


I. Water quality is related to:

            1. ecosystems

            2. drinking water (see Tab. 17-2 for EPA standards)

            3. recreation

            4. irrigation

            5. industrial utilizations, ie., hydroelectric power plants

            6. others


II. Types of water pollutants.

    A. Sediment.

            1. clay, silt, fine sand, organic debris

            2. Na+ flocculates clay; Al3+, Ca2+, and Mg2+ flocculate

            3. colloidal surfaces (negatively charged) of clay can hold plant nutrient cations

            4. pesticides and other negatively charged organics can be carried with clay


    B. Heat. 

    C. Dissolved gases, or lack of dissolved oxygen

    D. Sewage: microorganisms.

            1. BOD = Biological Oxygen Demand, a measure of microbial activity

            2. P, fecal coliform bacteria, S, N, detergents, pharmaceuticals, etc

    E. Manures from animals

    F. Petroleum products

    G. Toxic metals, ie., As, Cd, Pb, Hg,

    H. Acidity, salinity,


III. Groundwater contamination.

     A. Sources of entry:

            1. wells

            2. preferential flows via cracks, fissures, animal tunnels, etc.

            3. seawater intrusion from deep pools of salt water

            4. old land fills


IV.  Summary:  Four main groups of water pollutants:

            1. eroded sediment

            2. heat

            3. organic

            4. heavy metals


      Others: microorganisms, plant nutrients, radioactive nucleotides, pharmaceuticals,