Ecological Footprint & Carbon Footprint

 What is Ecological Footprint and Why is it Important? 

The ecological footprint (EF) represents the area of land on earth that provides for resources consumed and that assimilates the waste produced by a given entity or region.

The Ecological Footprint is a measure of how much biologically productive land and water area is used by an individual, a city, a country, a region, or humanity to produce the resources it consumes and to absorb the waste it generates, using prevailing technology and resource management. 

The ecological footprint thus measures human demand on nature, i.e., the quantity of nature it takes to support people or an economy. It includes the biologically productive area needed to provide for fruits and vegetables, fish, wood, fibres, absorption of carbon dioxide from fossil fuel use, and space for buildings and roads. 

In short, it is a measure of human impact on Earth’s ecosystem. 

The EF is beneficial because it provides a single value (equal to land area required) that reflects resource use patterns. The Ecological Footprint is most commonly expressed in units of global hectares. 

The use of EF in combination with a social and economic impact assessment can provide a measure of sustainability. It can help find some of the “hidden” environmental costs of consumption that are not captured by techniques such as cost-benefit analysis and environmental impact. Using the ecological footprint, an assessment can be made of where the largest impact comes from.

Biocapacity (or biological capacity) is the capacity of ecosystems to produce useful biological materials and to absorb waste materials generated by humans. “Useful biological materials” are defined for each year as those used by the human economy that year. What is considered “useful” can change over time. 

Like the Ecological Footprint, biocapacity is usually expressed in units of global hectares, and is calculated for all biologically productive land and sea area on the planet. 

Biologically productive area is land and water (both marine and inland) area that supports significant photosynthetic activity and biomass accumulation that can be used by humans. Non-productive and marginal areas such as arid regions, open oceans, the cryosphere, and other low-productive surfaces are not included. Areas producing biomass that is not of use to humans are also not included. 

In 2003 (the most recent year for which consistent data are available), the biosphere had 11.2 billion hectares of biologically productive area, corresponding to roughly one quarter of the planet’s surface. 

The process of measuring both the Ecological Footprint and biocapacity of a business, nation, region, or the planet is often referred to as Ecological Footprint accounting. 

In 2003, global Ecological Footprint accounts showed that humanity’s total Footprint exceeded the Earth’s biocapacity by approximately 25 per cent. 

Ecological Footprint accounting is based on some fundamental assumptions: 

• The majority of the resources people consume and the wastes they generate can be tracked.

• Most of these resource and waste flows can be measured in terms of the biologically productive area necessary to maintain these flows. Resource and waste flows that cannot be measured are excluded from the assessment, leading to a systematic underestimate of the true Ecological Footprint. 

• By weighing each area in proportion to its bio-productivity, different types of areas can be converted into the common unit of global hectares, with world average bio-productivity. 

• Human demand, expressed as the Ecological Footprint, can be directly compared to nature’s supply, biocapacity, when both are expressed in global hectares. 

Area demanded can exceed area supplied if demand on an ecosystem exceeds that ecosystems regenerative capacity (e.g., humans can temporarily demand more biocapacity from forests, or fisheries, than those ecosystems have). This situation, where Ecological Footprint exceeds available biocapacity, is known as overshoot. 

Because the Footprint is a historical account, many activities that systematically erode nature’s future regenerative capacity are not included in current and past Ecological Footprint accounts. 

These activities include the release of materials for which the biosphere has no significant assimilation capacity (e.g. PCBs, dioxins, and other persistent pollutants) and processes that damage the biosphere’s future capacity (e.g. species extinction, salination resulting from cropland irrigation, soil erosion from tilling). 

The consequences of these activities will be reflected in future Ecological Footprint accounts as a decrease in biocapacity. 

However, Ecological Footprint accounting does not currently include risk assessment models that would allow a present accounting of these future damages. 

A carbon footprint is the total amount of Greenhouse Gases – GHGs (especially carbon dioxide and methane) released into the atmosphere by different human activity.

1. Carbon footprints can be associated with an individual, an organization, a product or an event.

2. According to the World Health Organization (WHO), a carbon footprint is a measure of the impact people’s activities have on the amount of carbon dioxide (CO2) produced through the burning of fossil fuels and is expressed as a weight of CO2 emissions produced in tonnes.

3. The carbon footprint is seen as a subset of the ecological footprint, where carbon footprint deals with resource usage but focuses strictly on the greenhouse gases released due to burning of fossil fuels, while the latter compares the total resources people consume with the land and water area that is needed to replace those resources. 

4. The release of Six Greenhouse gases as recognized by the Kyoto Protocol will be counted in the carbon footprint. The Six GHGs are –

• Carbon dioxide (CO2)

• Methane (CH4)

• Nitrous Oxide (N2O)

• Hydrofluorocarbons (HFCs)

• Perfluorocarbon (PFCs)

• Sulphur hexafluoride (SF6)

2. Carbon footprints are usually measured in equivalent tons of carbon dioxide – CO2e, during the period of a year. 

3. CO2e is calculated by multiplying the emissions of each of the six greenhouse gases by its 100 year global warming potential (GWP).

4. On comparing various forms of energy generation Coal has the largest Carbon footprint among others followed by Oil, Natural Gas and Geothermal Energy.

5. Carbon footprints are of Two types –

• Organizational – Emissions from all the activities across the organisation such as energy use, industrial processes and company vehicles.

• Product – Emissions from the extraction of raw materials and manufacturing right through to its use and final reuse, recycling or disposal i.e. over the whole life of a product or service.

Effects of Increased Carbon Footprints

1. Large Scale resources are depleted with increased carbon emissions, from deforestation activity in a country to an increased use of air conditioners in our homes.

2. Carbon footprints have great effects on climate change. Emission of Greenhouse Gasses in the atmosphere leads to warming of the planet.

• According to World Meteorological Organization (WMO) records, 2011-2020 was the warmest decade on record, in a persistent long-term climate change trend.

• From 1990 to 2005, the emissions of carbon dioxide increased by 31%. By 2008, the emissions had contributed to a 35% increase in radiative warming, or a shift in Earth’s energy balance toward warming, over 1990 levels.

Steps to Lessen Carbon Footprints

The average carbon footprint globally is closer to 4 tons. It needs to drop under 2 tons by 2050 in order to avoid the chance of 2 degree celsius rise in the Global Temperature. 

The actions by which we can help reduce the carbon footprints are –

1. It can be reduced through improving energy efficiency and changing lifestyles and purchasing habits, such as-

• Avoiding the products with lots of packaging

• Adopt 4 R’s – refuse, reduce, recycle, reuse

2. Switching one’s energy and transportation use can have an impact on primary carbon footprints.

• Replacing regular light bulbs with compact fluorescent lamp – CFL

3. A ton of carbon dioxide is released when we for example travel 5000 miles in an airplane or drive 2,500 miles in a medium – sized car, hence

• Avoid taking connecting flights

• Take public transport or drive a more efficient vehicle. 

• Walk or use bicycles instead of using bikes, cars, etc. 

4. Switching from coal to a less carbon-intensive energy source.

5. Planting more trees.

Cultivation of anaerobic bacteria –Production of vacuum, displacement of oxygen with other gases, chemical methods, biological methods and reduction of medium.

  Cultivation of anaerobic bacteria–Production of vacuum, displacement of oxygen with other gases

Anaerobic bacteria differ in their sensitivity and requirement to oxygen. Some are aerotolerant while some are strict anaerobes. Anaerobiosis is achieved by different methods such as exclusion of oxygen, or production of vacuum, displacement of oxygen with other gases, absorption of oxygen by physical or chemical means, and reduction of oxygen.

1.     Production of vacuum

Cultivation in vacuum is done by incubating cultures in a vacuum dessicator. This method is unsatisfactory since some oxygen is always left behind.  The fluid cultures may boil over and the media may get detached from the plates in the vacuum produced. So, this method is not in much use now.

2.     Displacement of oxygen with other gases

Displacement of oxygen with other gases such as hydrogen, nitrogen, helium, or carbon dioxide is another method but this rarely results in complete anaerobiosis.

Another popular method is the use of candle jar.

Candle jar

A candle jar is a container into which a lit candle is introduced before sealing the container's airtight lid. The candle's flame burns until extinguished by oxygen deprivation, which creates a carbon dioxide-rich, oxygen-poor atmosphere in the jar. Candle jars are used to grow bacteria requiring an increased CO₂ concentration (capnophiles). Candle jars increase CO₂ concentrations but there is some amount of O₂ left and compete anaerobiosis is never achieved to grow complete anaerobes.

Microaerophiles can be easily cultivated in a candle jar in the laboratory. A microaerophile is a microorganism that requires lower levels of oxygen than are present in the atmosphere (20% concentration), to survive. Many microaerophiles are also capnophiles, as they require an elevated concentration of carbon dioxide. Candle jars are ideal for cultivating them. The candle jar provides a concentration of carbon dioxide which stimulates the growth of microaerophiles/ capnophiles. 

 

Overall efficiency of candle jars:

For Anaerobic Bacteria:

• Limited Effectiveness: Candle jars are not generally considered reliable for culturing strict anaerobes. While the burning candle consumes oxygen, it doesn't create a truly anaerobic environment. Some oxygen usually remains, which can inhibit or kill strict anaerobes.
• Microaerophilic Conditions: The candle jar creates more of a microaerophilic environment (low oxygen) than a truly anaerobic one. This might be sufficient for some microaerophiles, but not for strict anaerobes.  
• Inconsistent Results: The level of oxygen reduction in a candle jar can be variable, depending on the size of the jar, the size of the candle, and other factors. This makes it difficult to control the exact atmospheric conditions and leads to inconsistent results.

For Capnophilic Bacteria:

• Enhanced CO₂: Candle jars are more effective for growing capnophilic bacteria. The burning candle produces carbon dioxide (CO2), which these organisms require for optimal growth.  
• Suitable CO₂ Levels: The CO₂ concentration achieved in a candle jar is usually sufficient to promote the growth of most capnophiles.
• Convenience: Candle jars are a relatively simple and inexpensive method for creating a CO2-enriched atmosphere for capnophiles.  

Overall Efficiency:

• Capnophiles: The candle jar is a reasonably efficient and convenient method for cultivating capnophilic bacteria. It provides a reliable way to increase CO2 levels, promoting their growth.
• Anaerobes: The candle jar is not an efficient or reliable method for growing strict anaerobes. It does not consistently create a truly anaerobic environment, and other methods (e.g., anaerobic chambers, GasPak systems) are much more suitable. It might work for some microaerophiles which prefer reduced oxygen, but its anaerobic capability is limited.

In summary: The candle jar is a useful tool for culturing capnophiles due to its CO₂ production. However, it is not a reliable method for culturing strict anaerobes, and inconsistent for microaerophiles. More stringent methods are required for anaerobic work.

 

3.     Chemical methods for absorption of oxygen

In the chemical method, alkaline pyrogallol absorbs oxygen. First introduced by Buchner in 1888, this method has since been used with different modifications to produce anaerobiosis.

Pyrogallic acid is added to a solution of sodium hydroxide in a large test tube placed inside an airtight jar to provide anaerobiosis. A small amount of carbon dioxide is formed during the reaction, which may be inhibitory to some bacteria. The method is applied to single tube and plate cultures.

The spray anaerobic dish is a glass dish with its bottom partitioned into two halves. Pyrogallic acid and sodium hydroxide are placed in the separate halves at the bottom of the dish. The top half of petri dish contains the medium.  The inoculated top half  is inverted on top of the bottom half and sealed completely. The dish is then rocked to mix the reagents, producing complete anaerobiosis. The anerobic dish is not in much use now.

A simple modification consists of a Petri dish, between the two halves of which is inserted a metal disc of slightly larger diameter, with a hole in the centre. The metal disc is attached to the bottom half of the petridish with plasticine. Through the central hole, a few pellets of sodium hydroxide and 10 ml of a 10% solution of pyrogallic acid are added. The inoculated half of the petri dish in then inverted on the metal disc and sealed tightly.

Another common method, is the use of a disc of filter paper with the same diameter as a petri dish. It is placed on the top of one half of the dish and a mixture of pyrogallol and sodium carbonate, in dry powder form is spread on it. The inoculated petri plate is inverted over the filter paper and sealed tight with molten wax. The dry pyrogallol mixture is activated by the moisture within the closed system and complete anaerobiosis develops within about two hours.

Instead of alkalline pyrogallol, anaerobiosis is achieved by the use of a mixture of chromium and sulphuric acid (Rosenthal method) or with yellow phosphorous.

1.     Gas pack

Gas packs which can generate CO₂ are generally used in place of candle jars. Gaspak is commercially available as a disposable envelope, containing chemicals which generate hydrogen and carbon dioxide on the addition of water. The inoculated plates are kept in the anaerobic jar, the Gaspak envelope with water added is placed inside and the lid screwed tight. Hydrogen and carbon dioxide are liberated and in the presence of a catalyst such as palladium in the envelope, hydrogen and oxygen combine thus resulting in an anerobic environment.  The Gaspak is simple and effective. Gaspak reduces the oxygen concentration to about 5% and provides CO₂ concentration of about 10%.

An indicator such as reduced methylene blue can be used to verify the anaerobic condition in the jars. It remains colorless anaerobically but turns blue on exposure to oxygen.

2.     Anaerobic jar

The most widely used and reliable anaerobic method is McIntosh-Filde’s anaerobic jar. It consists of a stout glass/metal jar with a metal lid which can be clamped air tight with a screw. The lid has two tubes with taps, one acting as gas inlet and the other as gas outlet. The lid has two terminals which can be connected to an electric supply. On the underside of the lid is a small catalyst chamber containing a layer of palladinised asbestos. Palladium acts as catalyst to combine O₂ in the jar with H+ thus removing O₂.

Inoculated culture plates are placed inside the jar, and the lid clamped tight. The outlet tube is connected to the vacuum pump and the air inside is evacuated. The outlet tube is then closed an dthe inlet tube connected to a hydrogen supply. After the jar is filled with hydrogen, electric terminals are connected to a current supply and palladinised asbestos heated. This acts as a catalyst for the combination of hydrogen with any remaining oxygen present in the jar. . This method ensures complete anaerobiosis. 

There is a risk of explosion which can occur rarely. This can be avoided by modifying the catalyst. Alumina pellets coated with palladium suspended from the lid of the jar act as a catalyst at room temperature, as long as the sachet is kept dry.

      

 3.     Biological methods

Biological methods to establish anaerobic conditions rely on the activity of other microorganisms or biological processes to consume oxygen within a closed environment. Biological method can be used to establish anaerobic conditions.

1. Co-cultivation with Facultative Anaerobes: A facultative anaerobe is a microorganism that can grow in both aerobic (with oxygen) and anaerobic (without oxygen) conditions.

A strict anaerobe when grown with a facultative anaerobe in a sealed container, the facultative anaerobe will use up any available oxygen in the container as it grows. Once the oxygen is depleted, the environment becomes anaerobic, allowing the strict anaerobe to grow. The facultative anaerobe acts as an "oxygen sink."   One half of the solid medium in the Petri´s dish is inoculated with the tested sample, the second half is inoculated with facultative anaerobe which is able to produce anaerobic environment by the consumption of oxygen. Petri dish is sealed with the wax or parafin and cultured.

2. Use of Anaerobic Indicator Organisms: Some microorganisms are very sensitive to oxygen and can serve as indicators of anaerobic conditions. Such an indicator organism, if included along with target anaerobe, its growth (or lack thereof) can tell if truly anaerobic conditions have been achieved. A classic example is Clostridium species, which are strict anaerobes. Their vigorous growth would suggest a suitably anaerobic environment.  
3. Metabolic Activity of the Culture: In some cases, the anaerobic culture itself can create its own anaerobic environment. As the anaerobes grow, they consume available nutrients and produce metabolic byproducts, some of which can further reduce the oxygen levels or create a reducing environment. This is particularly true in deep, unshaken liquid cultures where oxygen diffusion into the lower parts of the culture is limited.
4. Use of Oxygen-Reducing Enzymes: While not strictly a "biological method" in the sense of using whole organisms, some research or industrial applications might use oxygen-reducing enzymes (like oxido-reductases) derived from biological sources. These enzymes can be incorporated into the media to chemically remove oxygen. This is more of a biochemical approach, but it leverages biological molecules to achieve the desired result.

While these biological methods can be useful in certain situations, they are often less precise and reliable than physical or chemical methods (like GasPaks or anaerobic chambers) for establishing strict anaerobiosis. They are more likely to be employed in situations where those more sophisticated tools are not available.

 

4.     Reduction of oxygen in the medium is achieved by using various reducing agents such as 1% glucose, 0.1% thioglycolate, 0.1% ascorbic acid and 0.05% cysteine.

 

5.     Anaerobic chamber

For fastidious anaerobes, pre-reduced media and an anaerobic chamber (glove box) may be used. The anerobic chamber is an air-tight, glass fronted cabinet filled with inert gas with an entry slot for the introduction and removal of materials and gloves for the hands.