MT

Hydrosphere

Water

  • substance made up of hydrogen and oxygen

  • can take solid, liquid, and gaseous forms

  • most abundant substance on earth

  • about 71% of the earth’s surface is covered by water

  • the total amount of water is constant, but what changes are its quality, distribution and availability

Important Properties

  1. a solvent that is able to dissolve and transport ions and molecules

    • solvent: something that can dissolve other substances

      • water is a special solvent because it can dissolve many substances = “universal solvent”

    • ions: tiny pieces of substances that have an electric charge

    • molecules: groups of atoms stuck together

    • water not only dissolves these substances, but also moves them around

    • water helps living things get the nutrients they need and cleans things like our bodies, rivers, and oceans by carrying away substances that are dissolved in it

    • BUT this ability of water to act as a solvent also means that it is easily polluted

  2. has a relatively high heat of vaporization

    • heat of vaporization: amount of energy needed to convert a substance from liquid to vapor state

      • high heat of vaporization means high absorption of heat when it evaporates = cooler surroundings

      • plays an important role in global climate and weather patterns

  3. has a relatively high heat capacity

    • heat capacity: ability of a substance to absorb or release heat without a large temperature change

      • high heat capacity = can solve large amounts of heat

  4. is the only natural substance that expands when it freezes

    • ice had lower density than liquid water

    • since ice forms at the top first, life can still go on under water

  5. has the ability to solvate the hydrogen ion and dissociate into H+ and OH-

    • pH is a way to measure how acidic or basic (alkaline) a substance is

      • acids: release hydrogen ions (H+) when they are in water

        • high hydrogen ions = stronger acid

      • bases: release hydroxide ions (OH-) when they are in water

        • high hydroxide ions = stronger base

Hydrologic Cycle

  • our water supply heavily depends on the water cycle

    • more rain = more flow in rivers, more groundwater

  • rain that does not soak into the ground becomes runoff and carries soil, pollutants, and other materials from the land into our rivers, lakes, and bays

Residence Time

  • amount of time that a water molecule stays within a particular hydrologic cycle

  • average residence time of water in the water cycle

    • more mobility = less residence time

  • water vapor

    • most mobile form of water = shorter residence time

    • water locked in solid phase = longest residence time

  • bigger reservoir = higher residence time

  • lower residence time = pollutants can be flushed out rapidly

  • more residence time = harder to clean

  • is water a renewable source?

    • depends on the source of water and its associated residence time

Water and Society: Human Impacts

Consumptive Use

  • water quality is degraded from its use

  • ex: municipal, industrial, agricultural uses

Non-Consumptive Use

  • water quality is unchanged, unless pollution occurs during use

How Humans Use Freshwater

Philippine Classification of Water Uses

Surface Water Pollution

Point Source

  • single, identifiable source of pollution

  • ex: pipe or drain from a factory or sewage treatment plant

Non-Point Source

  • pollution cannot be traced to a single point of origin

  • ex: agricultural runoff which can accumulate from multiple source

Common Types of Water Pollutants

  • biodegradable wastes (food wastes, organic matter, toilet wastes)

    • high BOD (biochemical oxygen demand): amount of oxygen used by microorganisms to break down organic matter in water

  • soaps and detergents

    • some contain non-biodegradable ingredients

    • chemical pesticides: contain organic pollutants

Surface Water Pollution

  • MT Terranova Oil Spill in Manila Bay (2024)

    • carrying 1.4 million liters of industrial fuel oil

    • reached the coasts of Cavite, Pampanga and Metro Manila

  • MT Solar 1 Oil Spill in Guimaras (2006)

    • spilled 2.4 million liters of oil affected 16 km coral reefs, 551 hectares of mangroves, 58 hectares of seaweed and 824 hectares of fishponds

Threats the Groundwater Sources

  • sea level rise and overdrawing of groundwater near coastal areas can lead to intrusion of saltwater

  • irresponsible mining

  • seepage from septic tanks

  • persistent organic pollutants (ex: pesticides)