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Can Carbon Cycle Save Us from Climate Change???

I was preparing for Atmospheric Chemistry’s exam when this question popped up in my mind. So, first of all, I hope you all know about our beloved Carbon Cycle. You should also know that carbon dioxide is a major greenhouse gas and recently its concentration in atmosphere has increased to 400ppm mainly due to human activities.

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So, now comes the question how carbon cycle acts as a thermostat for our Earth? It does so mainly by positive and negative feedback mechanisms. In positive feedback, the processes that are occurring in nature are enhanced (for example, upon increase in temperature these mechanisms support warming), while in negative feedback mechanisms, the processes are opposed (for example, upon increase in temperature these mechanisms support cooling). Maybe this figure will explain them better than I can!!

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Here Albedo means the reflectance of radiations from ice surfaces, thus decreased albedo means high absorbance of radiation. 

 

Now let’s observe how climate change affects carbon cycle and its feedback mechanisms.

  1. Terrestrial Environment 

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In some areas where temperature increases due to climate change, there will be an increase in respiration by plants and this will reduce carbon storage in plants, releasing more carbon dioxide to the atmosphere (positive feedback). Though, in other areas where decrease in temperature occurs, the period of photosynthesis will increase as respiration will be slow, thus carbon will be stored from atmosphere (negative feedback). More carbon dioxide concentrations also support higher rate of photosynthesis.

Similarly, soil stores more carbon at colder temperature and high precipitation as rate of decomposition is reduced. 

This table clearly represents how various factors effect feedback mechanisms.

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2. Ocean Feedbacks
CO2 is far more soluble in colder water than in warmer water, thus warmer sea surface temperatures will affect the oceans’ ability to dissolve CO2 and their carbon chemistry. A warmer ocean might cause dissolved organic carbon to decompose faster and convert to CO2, reducing the amount of atmospheric CO2 that can be absorbed by the oceans (a positive feedback). Warming might also cause a decrease in the extent of sea ice, which could increase plankton and other marine growth in high-latitude regions. This would result in a greater uptake of atmospheric CO2, thereby acting as a negative feedback (Read more here).

Evidence exists that the relationship between climate change and carbon cycle will be very important in the future for determining emissions and carbon dioxide concentrations in the atmosphere.

Increasing Efficiency of Solar Cells by Mimicking Cabbage White Butterflies

A team of researchers from the University of Exeter has shown that the efficiency of solar panels can be increased by nearly 50% by mimicking the v-shaped posture adopted by Cabbage White butterflies to heat up their flight muscles before take off.

08-sn-univ-butterflies-fig1                              butterfly-technique

The angle at which these butterflies hold their wing is approximately 17 degrees. This is the reason due to which these butterflies take flight before other butterflies on cloudy days.

The research team analyzed and tried to replicate the butterfly wing structure to create a new lightweight reflective material with the capability to produce solar energy. The process produces not only lighter, but also more efficient panels.

 

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Use of Mercury for Artisanal and Small-Scale Gold Mining

This specific issue became evident to me when I surfing twitter. Artisanal and small-scale gold mining (ASGM) is the extraction of minerals by miners working in small and medium sized operations, using rudimentary techniques.  Simple practices with minimum economic investment are employed be these miners. It is the largest intentional-release source of mercury in the world.

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How can mercury be used for gold-mining? Mercury is used to separate and collect the gold from the rocks. Mercury binds with gold to form an amalgam which facilitates it to separate from rock, sand or other material. The amalgam is then heated to vaporize the mercury leaving the gold behind.

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Mercury is a powerful neurotoxin that is harmful to people, especially to developing fetuses, and young children. Once emitted, it can travel great distances through the atmosphere, causing global contamination of ecosystems, fish, birds, mammals, and the human food chain.Local exposures in mining communities that use mercury can be acute.

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What to do now?

  1. The most important measure a mining community can take to reduce its mercury use is to concentrate the gold-containing portion of the ore before adding mercury. This can be done by crushing and grinding the ore and then using carpeted or magnetic sluice boxes or gravity concentration techniques such as panning or centrifuges. In this way, more gold will be captured, less mercury will be required and residual mercury can be more completely captured.
  2. Protective measures include the use of retorts when burning amalgam and the use of gloves by those handling mercury or amalgam.
  3. Most promising technology to replace the use of mercury is cyanidation, but this method may not be affordable or technically available to all artisanal miners. Also, cyanidation methods must be used with care and carefully introduced due to its significant risks to human health and the environment.

For further info check reference texts http://www.unep.org/hazardoussubstances/Portals/9/Mercury/AwarenessPack/English/UNEP_Mod3_UK_Web.pdf

http://www.unep.org/hazardoussubstances/Portals/9/Mercury/Documents/ASGM/Techdoc/UNEP%20Tech%20Doc%20APRIL%202012_120608b_web.pdf

How to Make our Food Systems Sustainable?

(For those who don’t like reading science stuff scroll down and have a look at the infographics)

Agroecology is this short answer. It can help us establish sustainable food systems.

Just a few month back I was very surprised and unhappy that we were to be taught this subject. But since I attended this subject’s first class I have been in love with it. So, the first question in your mind would be what is wrong with our current food system. The following infographic will make that clear to you and later on I’ll ramble about it.

food-production-infographic

The current agriculture is highly dependent on human inputs. This dependence is mainly due to the agricultural practices  like monoculture (planting same crop over a larger area), intensive tillage, use of fertilizers, insecticides, pesticides, factory farming, etc. These practices make an ecosystem of their own that is agroecosystem. Agroecosystem cannot sustain itself. In this system, energy and nutrients are  lost. It is not resilient to disturbances and change. It has very simplified food chains. Hence, agroecology applies ecological principles to agroecosystems. This can be done by increasing biodiversity thus making food chains complex, agroecosystems stable, reducing dependence on human inputs, etc. Some of these methods have been beautifully described in the following  infographic.

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The difference between agroecological and conventional agricultural practices can be observed very clearly in this infographic. 

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Here goes an infographic about how agroecology relates to climate change.

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Sources of infographics have been linked.

Ever Used This Device?

I hope you did use it at some point of your lives. This pulse oximeter measures the oxygen level in blood and also records heart rate. It’s so amazing and thought provoking that such a small device can do such wonders. Let’s see how it does so!

pulse-oximeter

So, the basic principle of pulse oximetry is based on the red and infrared light absorption characteristics of oxygenated and deoxygenated hemoglobin. Oxygenated hemoglobin absorbs more infrared light and allows more red light to pass through. Deoxygenated hemoglobin absorbs more red light and allows more infrared light to pass through. Pulse oximeter uses a light emitter with red and infrared LEDs that shines through a reasonably translucent site with good blood flow.

figure-1-dr-petty-brochure An emitter and photo detector are involved in the transmission and receiving of these LEDs. After the transmitted red (R) and infrared (IR) lights pass through the measuring site and are received at the photodetector, the R/IR ratio is calculated. For example,

  1. a R/IR ratio of 0.5 equates to approximately 100% SpO2,
  2. a ratio of 1.0 to approximately 82% SpO2,
  3.  and a ratio of 2.0 equates to 0% SpO2.

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References and further reading

http://www.oximetry.org/pulseox/principles.htm

http://www.nonin.com/How-Does-a-Pulse-Oximeter-Work

How pulse oximeters work explained simply.