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Water on Earth

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    50825
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    Water on Earth

    800px-BlueMarble-2001-2002.jpg

    Figure \(\PageIndex{1}\) Two separate views of earth and all the water on it

    Water is one of the most important necessities to human survival. It is the most basic element of life. Water makes up over 71% of Earth’s surface, including lakes, rivers, and several oceans worldwide. The oceans contain 97.2% of the Earth’s water. It is important to understand that water must be kept in balance on earth. One source of water that is not widely known or thought about is ground water. It is an important resource because it replenishes our streams, rivers, habitats, and is able to provide fresh water for irrigation, industry, and communities. [1]

    Hydrology

    Hydrology is the study of the movement, distribution, and quality of water on Earth. This study includes the hydrologic cycle, water resources, and environmental watershed sustainability. More specifically there is chemical hydrology which is a subdivision of hydrology. This study is based on the chemical characteristics of water.

    Some major physical and chemical properties of water

    Visually, water is transparent. Water is a liquid at standard temperature and pressure. It is tasteless and odorless. Since the water molecule is not linear and the oxygen atom has a higher electronegativity than hydrogen atoms, it carries a slight negative charge. This charge is sometimes referred to as a partial negative charge (δ-). The hydrogen atoms in comparison carry a slightly positive charge (partial positive δ+). Due to this physical characteristic, water is a polar molecule with an electrical dipole moment. Water is also capable of forming intermolecular hydrogen bonds. Hydrogen bonding is the collection of strong intermolecular forces. In the Figure below, the dotted lines represents the hydrogen bond between water molecules. Each water molecule is hydrogen bonding to four other water molecules in a lattice. Hydrogen bonding is also the reason water has an unusually high boiling point.

    Water.JPG
    Figure \(\PageIndex{2}\). Model of water displaying hydrogen bonding

    Water Pollution

    Water pollution affects the environment not only because it kills the ecosystem, but because humans and animals alike get their drinking water from these various water systems. Animal and plant waste, which sometimes are discharged into streams and river ways, can be beneficial in some bodies of water by releasing nutrients in the form of nitrogen and phosphorus salts. In limited quantities it can be good because it stimulates plant and animal growth. In excessive quantities, the organic rich waste compounds can cause severe harm to the environment. Organic waste can come from multiple sources. This waste can potentially contaminate the water that may be intended for drinking depending on its location. Atrazine, and glyphosate are the names of contaminants that find their way into water as runoffs from pesticides used. The other means of contamination to water is by discharge from factories. Two examples of organic chemicals in this category are benzene and toluene. Water in general is a great solvent due to its polarity. This property allows equally polar waste compounds to be dissolved in it, leading to the contamination of water. Organic waste compounds containing elements with lone pairs (such as nitrogen or phosphorous) are readily dissolved due to the hydrogen bonding that will occur. This interaction can lead to another environmental occurrence of harmful algal blooms (HABs). According to the National Environmental Satellite, Data, and Information Service, HABs are microscopic, single-celled marine algae called phytoplankton that grow in a “bloom”. [2]

    From ChemPRIME: 8.10: Hydrogen Bonding: Water

    References

    1. www.epa.gov/ebtpages/wategroundwater.html
    2. www.science-house.org/nesdis/...ackground.html

    Contributors and Attributions


    This page titled Water on Earth is shared under a not declared license and was authored, remixed, and/or curated by Ed Vitz, John W. Moore, Justin Shorb, Xavier Prat-Resina, Tim Wendorff, & Adam Hahn.

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