Carbon Cycle

Link to see a bigger picture of the CC :)

Carbon is the major chemical constituent of many organic compounds like fossil fuels.

Carbon is stored on our planet in the following major sinks:

(1) as organic molecules in organisms (both dead and alive) found in the biosphere;

(2) as the carbon dioxide gas in the atmosphere;

(3) as organic matter in soils;

(4) in the lithosphere as fossil fuels and sedimentary rock deposits such as limestone;

(5) in the oceans as dissolved carbon dioxide and as calcium carbonate shells of marine organisms.

Feel free to go to http://www.youtube.com/watchv=U3SZKJVKRxQ&feature=related for a 5 min summary of the Carbon Cycle. Hopefully, it will help you remember it better :D


Interesting Idea(s) brought up during lesson:

• The idea of carbon credit VS carbon offset

 Carbon Offset
“A carbon offset is a reduction in emissions of carbon or greenhouse gases made in order to compensate for or to offset an emission made elsewhere.”
Taken from http://en.wikipedia.org/wiki/Carbon_offset

Basically, carbon offset is a set of measures that helps to counter the impact of the carbon emissions by balancing the carbon output and input. For example, in an attempt to offset my carbon emissions from the combustion of fossil fuels, I plant the equivalent of 100 trees. This helps to balance the carbon input and output from the cycle.


 Carbon credit
“A carbon credit is a generic term for any tradable certificate or permit representing the right to emit one tonne of carbon or carbon dioxide equivalent (CO2-e). Carbon trading is an application of an emissions trading approach.”
Taken from http://en.wikipedia.org/wiki/Carbon_credit

Basically, carbon credit is the trade between countries/companies about the right to emit carbon. Parties, who need to emit more carbon, have to buy the right from parties who have excess credits, to emit their extra carbon. This helps to regulate the amount of carbon released into the atmosphere globally, by regulating the amount of carbon emitted to a price.

My opinions on carbon credit and credit offset
Personally, I feel that the purpose of the carbon credit (which is to reduce the amount of carbon emissions by increasing the finianical costs of it) is very much limited by man's need to emit carbon. Thus, it is unable to fully meet its inital purpose. Well it deters a handful companies and countries from reducing their emissions, it doesnt stop those who really need and can afford to emit carbon.

On the other hand, I feel that credit offset is a better alternative to control the amount of carbon emission since it tackles the output and input of the carbon cycle (property of a system :D). However, it will not be the best alternative, especially for sustained periods of time. This is because, even if i plant trees in hope of reducing my country's carbon emissions, the same amount of carbon (or even more) will still be released when the trees die. Furthermore, there are that many trees you can plant.

However, on the whole, its still a better alternative compared to carbon credits :)

What do you think? Free feel to share your views in the comments :D

Nitrogen Cycle (II)

Nitrogen is used by living organisms to produce a number of complex organic molecules. (as mentioned by Cho Ling above) Major stores of nitrogen include the atmosphere, living organisms, and organic matter in soil and the oceans.

Figure 1: Yellow arrows indicate human sources of nitrogen. Red arrows indicate microbial conversions of nitrogen. Blue arrows indicate physical forces acting on nitrogen. While green arrows indicate natural processes affecting the form of nitrogen.

The five main processes of the Nitrogen Cycle (taught in class)

1. Nitrogen fixation

2. Nitrogen Uptake

3. Nitrogen mineralisation (decay)

4. Nitification

5. Denitrification

Interesting Facts about the Nitrogen Cycle (:

• Scientists estimate that biological fixation globally adds ~140 million metric tons of nitrogen to ecosystems yearly.
• Denitrification is the only process that removes nitrogen from ecosystems, and it somewhat balances the amount of nitrogen fixed.
• The five processes in the nitrogen cycle-- are all driven by microorganisms.
• Human activities increase nitrate levels in drinking water by at least 10 times. From 1mg/L to 10mg/L.

 

WHAT GOES AROUND COMES AROUND

Like the Nitrogen Cycle, man and the atmosphere are both part of a system. Should one aspect of the system be affected (Eg. Nitrogen Cycle), later stages of the cycle would be affected too. (Eg. Man)

• Excess/unabsorbed fertilizer is washed off by irrigation/rain into groundwater or water bodies. Unfortunately, groundwater is often used as a direct drinking source.
  Excess nitrogen can lead to cancer in humans and respiratory problems in infants.
• On surface waters, excessive nitrogen can lead to eutrophication, the over-nourishment of phytoplankton. Eutrophication causes increased frequencies of coastal fish-kill events, harmful algal blooms, and even causes species shifts.
  (Hence, reduces the supply of fish and other seafood.)
• Atmospheric nitrogen (like NO₃^- and NH₄⁺) can also change the acidity of acid rain causing many long-term changes.For example forests' death and decline.
  (Hence, reducing the amount of carbon dioxide absorbed.)

Reflections and Key Learning Points

After last week's lesson and today's blog post, I have come to greater understanding about the word "systems", having applied it in today's blog post. I have come to understand that the man and the atmosphere are both part of a larger system, where if one aspect is missing/changes, it will ultimately affect the entire system. (Eg, the addition of man-made fertilizers) Ultimately, it will affect the entire Nitrogen Cycle and come back to affect Man.

"What goes around, comes around."

Personally, like the Carbon Cycle, i feel that each stage is as important as the next. There is a kind of interdepence within the cycle, without one the other cannot take place.  Another thing that I learnt while posting this blog entry was that microorganisms. Just when we thought they weren't so important, they're actually the driving force behind the whole cycle. I also marvel the work of Nature, how the whole large system can be at equilibrium so that there's just enough of everything to balance the entire Nitrogen Cycle :)

*Click the cycle for a bigger picture*