Major Pollution Problems Still Begging for Solutions (Eutrophication and Climate Change)
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January 17, 2020 at 2:53 pm #8218
Eutrophication (Depletion of Dissolved Oxygen)
The problem became evident in the 1960s in the form of massive fish kills. Type into your browser: fish kills images
Extensive research through the 1970 showed that the cause was not toxins; it was depletion of dissolved oxygen cause by over-abundance of nutrients, i.e., EUTROPHICATION, which comes about as follows. (Be sure students understand the sequence of steps.)
- Not all the fertilizer applied to crops, lawns, and gardens gets absorbed by crop plants. Excess leaches into waterways.
- Excess nutrients in waterways stimulates overgrowth of microscopic algal organisms, PHYTOPLANKTON. (See: algal blooms images)
- Algal blooms shade out bottom plant life, the natural aquatic oxygen producers.
- Phytoplankton cells die, sink, and are fed upon by bacteria which consume oxygen.
- Dissolved oxygen is depleted and fish suffocate
Eutrophication is a worsening problem worldwide. Type into your browser: ocean areas suffering from eutrophication map
Discuss: what can be done about it?
The key points for the argument that humans are the cause behind climate change may be outlined as follows. See text for more detail
- The temperature of every inanimate body is an equilibrium between energy inputs and energy outputs
- Temperature of a body may be raised by increasing heat input OR, leaving heat input the same and reducing heat output.
- For planet Earth the body: energy input is mostly in the form of light from the sun; heat output is infrared (heat) radiation from the earth to outer space. The climate we experience is the equilibrium.
- Carbon dioxide allows light energy from the sun (energy input) to pass freely but absorbs and traps infrared (heat) radiation (energy output)
- From the burning of fossil fuels, we are increasing the level of carbon dioxide in the atmosphere. Type into your browser:
carbon dioxide concentration in the atmosphere graph
Conclusion: Energy input, light energy from the sun remains constant. Energy output, heat radiation to outer space is increasingly blocked by increasing concentration of CO2 in the atmosphere. This is like putting an extra blanket on our bed; it can only lead to warmer temperatures.
6. Evidence that global temperatures are rising. Type into your browser: evidence for global warming
See especially: https://climate.nasa.gov/evidence/
Also, type into your browser: ecological effects of climate change
See especially: https://www.nceas.ucsb.edu/science/climate
Involve students in discussion as to what can be done/they can do about these problems. Please post comments including counter arguments.
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