Geography Exit#7

#7. Discuss how humans can pollute rivers and lakes. How can we detect such pollution and measure its intensity?

Pollution of Rivers and Lakes

·         Industrial Pollution

Industries that are located at rivers and lakes discharge wastewaters, highly toxic chemicals, debris and trash into these water bodies.

o   Wastewaters

§  Factories use water from rivers and lakes to cool down or power machineries.

§  The same water is cleaned and put back into the rivers and lakes.

·         It causes temperature change which is a serious threat to wildlife in these rivers and lakes. It causes the extinction of fished and other species.

·         Many times the water still contains some radioactivity.

§  Discharged wastewater, especially when it is untreated or only partially treated may lower the amount of dissolved oxygen in the receiving rivers or lakes. The oxygen is required by microorganisms that consume the organic material.

·         It might contain organic or inorganic material (when not treated or partially treated)

§  Oil tankers, or regular ships that spill petroleum, trash or waste into the rivers harm the natural habitat

o   Agricultural Pollution

§  River water is heavily used for agriculture. It is used to react with fertilizers that are used for crops. It turns the fertile soil toxic.     

§  The runoffs cause many fish species to die due to the high toxic pesticides in rivers. It can nearly wipe out an entire species.

§  Lakes also suffer tremendously under agricultural pollution. Excessive nutrients that enter water bodies such as lakes stimulate excessive plant growth such as algae.

§  This algal bloom reduces the dissolved oxygen in the water when dead plant material decomposes and causes other organisms to die. This process is known as Eutrophication.

§  These nutrients come from many sources: Fertilizers or golf courses.

•  
  • Air Pollution
    • Factories that release toxic chemicals from smokestacks into the air.
      • The dirt in the atmosphere sinks down to the ground and is visible as a very thin layer on lakes for example.
    • Acid Rain
      • There are several ways acids can fall out of the atmosphere. There are two parts: Wet and Dry.
      • Wet
        • Through rain, snow or fog it falls down to the earth and affects plants, animals, buildings, forests, rivers and lakes.
      • Dry
        • Dry deposition refers to acidic gases and particles that fall down to earth. Winds blow these acidic particles and gases onto buildings, cars, homes, trees and also rivers and lakes.
  • All these kinds of pollutions are related to Point and Non-Point Source Pollution as Humans are not directly involved in all kinds of pollutants.

How to detect Pollution and to measure its Intensity

• Air Pollution
  • Acid Rain is measured using a scale called “pH”.
    • The lower a substance’s pH the more acidic it is.
    • Pure Water has a pH of 7.0; rain is slightly acidic due to dissolved carbon dioxide, so it has a pH of about 5.5.
  • One way of detecting the air pollution caused by factories or car exhausts would be to see the thin layer of dirt that appears on water.
• Agricultural Pollution
  • Agricultural pollution can be detected by taking biological and chemical samples over a period of time and analyze and observe the increasing or decreasing results.
  • Implement new rules and regulations and increase the awareness of nature, so that farmers stop using toxic pesticides which harm the environment and groundwater.
• Wastewater Pollution
  • Wastewater or water pollution generally, can be detected by its appearance or odor.
    • If oil or foam is floating on it, then it is also an indicator for water pollution.
    • Also a lot of dead fish floating on the surface of a lake would be a clear sign that something is wrong.
  • In order to exactly measure its intensity there are several ways of measurements:
    • Filtration
      • Water is passed through a fine-pore filter. This separates suspended from dissolved portions of the analyte.
      • The filter may be used to clarify the water for analysis of a dissolved material.
    • Gravimetric Analysis
      • For a measurement of milligrams per liter of solids in the water, a measured volume of sample can be dried in a preweighed dish, then the dish and the solids are weighed after the water has evaporated.
      • The weight of solids is then calculated by subtraction and the concentration figured by dividing the weight of solids by the volume of the sample.
    • Distillation
      • Analyte is boiled out of the water, and then the vapors can be cooled and re-condensed or trapped in a liquid form in a different container.
      • This way the analyte can be removed from the interfering substances in the original sample.
      • Often the sample is made acidic, alkaline or treated chemically in some other way before distillation, to convert the analyte into an easily evaporated form.

•  
  •  
    • Algae’s are used to measure the pollution of water.
      • Scientists determine the water pollution by listening to the sound waves produced by tiny pieces of floating algae.

Advertisement