Water and water pollution - Chapters 13-14 - Chemistry of the environment

4 physical properties of water

1. liquid at room temp (but exists naturally in all phases)
2. universal solvent
3. less dense in solid form
4. high heat capacity

evaporation

slow conversion of a liquid into its vapor without reaching the boiling point

oceans

• largest water compartment
  • 97% of all water on planet
• Saltwater → unusable

glaciers, ice, and snow

• Three-fourths of the water is frozen
• freshwater

Groundwater

• 3 zones
• freshwater compartment

zone of saturation

layer of soil that contains moisture and no air and is saturated with water

zone of aeration

layer of soil that contains moisture and air and is not saturated with water

water table

dividing line between zone of aeration and zone of saturation

aquifer

soil and water positioned above an impermeable layer of rock or clay

unconfined aquifer

• Water seeps from the ground surface directly above the aquifer
• recharge zone
  • part of an aquifer exposed to the surface so that water can infiltrate into the aquifer

confined aquifer

has little or no exposure to the surface where water can infiltrate

lakes and ponds

• inland depressions that hold water
• Temporary features of the geological landscape
• freshwater compartment

soil moisture

• Water found underground in the zone of aeration
• not counted as groundwater
  • cannot be accessed by well
• important for plant growth

3 types of water use

1. consumed

   1. removed and not replaced as liquid in general area of removal

2. degraded

   1. water returned to source but at lower quality

3. withdrawn

   1. all water taken for any purpose (returned or consumed)

aquifer depletion

• more water is withdrawn than gained
• Removing water from 1000 year old aquifers faster than it can be replaced amounts to mining “fossil water”
  • non-renewable resource
• Ogallala Aquifer – under Nebraska and 7 other states

subsidence

\n land sinks due to the removal of underground liquids such as water or oil

saltwater intrusion

• In coastal areas, saltwater from the ocean seeps in underground until it meets underground freshwater
  • interface develops between them
  • saltwater remains under freshwater due to higher density

water pollution

any chemical or biological change that adversely affects the aquatic life normally found in water or that makes water unfit \n for a desired use

point source

discharge of a water pollutant or pollutants from a specific \n location

nonpoint source

generalized discharge of a water pollutant or pollutants \n from runoff over a large area

organic materials water pollutant

mostly broken down by microorganism consumption

aerobes

oxygen-consuming microorganisms that use organic material as food and break the materials down \n into carbon dioxide, water, nitrates, phosphates, and sulfates

biochemical oxygen demand (BOD)

amount of oxygen required to decompose a given quantity of organic material

dissolved oxygen (DO)

concentration of oxygen dissolved in any sample of water

• levels <8ppm
  • certain species of fish will be put in jeopardy, and as the level drops further more and more aquatic organisms will be affected
• levels <2ppm
  • few forms of life can survive, and those that do are not the forms of life we usually like to have around

anaerobes

• Organisms that do not use oxygen in producing energy from biochemical energy molecules
• The products of this process include principally methane and related compounds

clean zone

natural state of river or other body of water

decomposition zone

area just downstream from a major waste discharge where the BOD is very high and the DO levels are declining rapidly

oxygen sag

decline in DO levels in a decomposition zone due to a major waste discharge

septic zone

area downstream from a major waste discharge where the \n BOD is still very high and the DO levels are very low and have yet to recover

recovery zone

area downstream from a major waste discharge just beyond \n where most of the organic material will have been decomposed and where the BOD is declining and DO levels are increasing

eutrophication

increase in the nutrient level in a lake or stream over time

oligotrophic

lakes and streams with few nutrients and a relatively low abundance of life

eutrophic

Lakes and streams with a large amount of nutrients and an abundance of life

mesotrophic

Lakes and streams with intermediate amounts of nutrients

3 categories of water treatment

1. purification for domestic use
2. treatment for specialized industry applications
3. treatment of waste water to make it safe for release or reuse

primary waste treatment

removal of insoluble matter such as grit, grease, and scum from water by screening

secondary waste treatment

action of microorganisms provided with added oxygen degrading organic material in solution or in suspension until \n the BOD of the waste has been reduced to acceptable levels

tertiary waste treatment

variety of processes performed on the effluent from secondary waste treatment

• suspended solids
• dissolved oxygen compounds
• dissolved inorganic materials