How does the pH environment (pH 4,6,8,10 and no buffer as a control) of the enzyme catalase (taken from the liver of Ovis aries) affect the rate at which Hydrogen Peroxide (H2O2) is broken down (measured in seconds, with ± 1s error)?
Ever since reading a fascinating article on the importance of catalase to the process of life, I have been intensely captivated by the process by which food is digested. My interest was especially piqued when I discovered it helped to break down the toxic hydrogen peroxide in our bodies – but that this hydrogen peroxide is only produced in the first place to prevent the formation of a more toxic substance – superoxide, which ‘rips ions apart’. I was also interested to learn that catalase has the highest turnover numbers of all enzymes – making it one of the fastest acting enzymes in existence.
Design of Experiment
I was heavily involved in a personal capacity with the design of the experiment. This was achieved through the conduction of a pilot study, where I chose to investigate the effect of pH on the activity of catalase (instead of the effect of changing temperature – an option which was also thought about).
In the pilot study, there was a range of independent variables, including the catalase concentration, the volumes of the substances, the volume of the pH buffer and the concentration of hydrogen peroxide After a good deal of trial and error, I decided to use 40 ml of 5vol concentration hydrogen peroxide, and a separate beaker containing 50ml of catalase solution – at a 0.1% concentration. After deliberation, it was decided that the pH buffer (the independent variable) was to be tested at graduated intervals of pH 4, 6, no pH (to serve as a control – leaving the pH at 7), 8 and 12. 15ml of each pH buffer was to be added each time, since during the pilot study we discovered that using 10ml did not give as pronounced effects as desired.
Background to Enzyme Catalysis
Enzyme catalysis requires that the substrate be brought into close proximity with the active site. When a substrate binds to the enzyme’s active site, it forms an enzyme-substrate complex and the enzyme catalyzes the conversion of the substrate into product (this is the ‘chemical reaction’), creating something called an enzyme-product complex. The enzyme and product then dissociate and since the enzyme was not consumed or used up in the process, it can continue to catalyze further reactions.
Hydrogen Peroxide (H2O2) is a toxic substance in the human body, which is often said to be created ‘by accident’ in respiration. The catalase enzyme breaks it down into Hydrogen (H2) and Oxygen (O2). This is an example of the liver performing its function of using specialized enzymes to help it break down toxic substances and thus make them safer for the body to process.
The prediction made at the start of the experiment was that the optimum pH for catalase activity was to be somewhere between pH 6 and 8. In the context of the experiment the prediction was that between pH 6 and 8, the time taken for the paper disc to rise would be lowest on average (due to faster H2O2 decomposition). At extremely high pH levels, the charge of the enzyme will be altered. This changes protein solubility and overall shape. This change in shape of the active site diminishes its ability to bind to the substrate, thus annulling the function of the enzyme (catalase in this case). This process of denaturing only occurs when the enzyme is operating in an environment outside of its optimum range. It is hypothesised that the optimum range for catalase in this IA is between pH 6 and pH 8.
A sketch of the graph of expected results is provided below.
Sketch Graph to show the expected effect of differing pH levels on the activity of the enzyme catalase.
The independent variable is the value of the pH buffer (from 1-7) which was used in each beaker of H2O2. 15ml was added each time using a graduated syringe.
The dependent variable is the time taken for the paper disc to fall through the 40ml of hydrogen peroxide and rise to the surface of the beaker. It was measured in seconds (s), with an error allowance of ± 1 second, to account for human error on the stopwatch.
There are four main control variables, which needed to be accounted for in this investigation. Temperature, substrate concentration, enzyme concentration and the presence of an inhibitor all needed to be controlled in order to produce valid results.
If the temperature is low, then this can result in there being insufficient thermal energy to meet the activation energy of the reaction – the decomposition of hydrogen peroxide by catalase. If the temperature is increased then the higher kinetic energy will result in more successful collisions between catalase enzymes and hydrogen peroxide substrates. At the optimal temperature – which is 37°C for catalase, then the rate of enzyme activity will be at its peak. Both high and low temperatures (approximately 10°C either side of the optimum) will cause enzyme stability to decrease – since the change in thermal energy will disrupt the hydrogen bonds within the enzyme. This can cause denaturation, following the loss of shape of the active site.
The entire experiment was conducted in a lab – which had a constant temperature of 25°C. In order to increase the temperature of the catalase to the required ‘optimum’ level, a water bath – measured electronically to be 37°C was used. This was monitored throughout the experiment to avoid any unwanted fluctuations. Windows were also covered with blinds to prevent any increase in the general temperature of the laboratory as a result of the sunny conditions outside.
Substrate Concentration and Enzyme Concentration
For similar reasons to temperature, increasing the substrate concentration (concentration of hydrogen peroxide) or the enzyme concentration (catalase) (initially, will lead to an increase in the rate of reaction. This is because there will be a greater number of successful collisions per unit time between substrate and enzyme. However, beyond the optimum level of substrate concentration – which through our pilot study we found to be 5vol. – the solution becomes saturated, and there is no further increase in rate. Similarly, saturation occurs beyond the optimum level of enzyme concentration – which we found in our pilot study to be 0.1% catalase.
Care was taken to ensure that the correctly labelled solution of hydrogen peroxide was used in each of the five beakers at each of the five pH levels. It was replaced every time the pH was changed (i.e. five times). Care was also taken to ensure that the paper disc was not mistakenly dipped into a stronger or weaker beaker of catalase than the 0.1% concentration that was decided upon.
Presence of Inhibitor
Inhibitors essentially alter the catalytic action of the enzyme – and can slow down and even stop the process of catalysis. This can be done by competitive, non-competitive and substrate inhibitors. In the case of catalase, two non-competitive inhibitors were identified for special concern. Any heavy metal ions (such as CuSO4) and also potassium cyanide (KCN) can bind to the catalase and decrease its activity.
Before the experiment began, all surfaces, beakers and other apparatus were sterilized and thoroughly cleaned, in order to create an environment that did not contain any enzyme inhibitors.
Thus the variables in the environment were kept constant (controlled) to allow for valid results by changing a single variable in the experiment – pH.
A pilot study was undertaken so that the most effective values – concentrations and volumes – could be determined ahead of the full investigation. In order to represent the full range of the pH scale, values of 4, 6, 8 and 10 (and no pH – leaving the pH at 7 for a control) were used. The time taken for the paper disc to rise and fall was too short when the 5% catalase was used, and similar problems were encountered when a concentration greater than 5vol. was used for the hydrogen peroxide. Finally, due to fluctuation in the results, it was decided to repeat the experiment 5 times at each pH, instead of the original 3 times. It was hoped that this would increase reliability.
Pour 40ml of Hydrogen Peroxide (H2O2) at 5vol. concentration into five 50ml beakers.
Pour 50ml of catalase solution at 0.1% concentration into a large beaker – for dipping the paper discs.
For four of the beakers, add 15ml of the selected pH buffer (beaker 1 – pH 4, beaker 2 – pH 6 and so forth all the way to pH 10). The fifth set should be left without a pH buffer to act as a control.
This 15ml should be measured carefully using a graduated syringe.
Using the forceps, immerse a paper disc of regular and consistent shape and size (taken from a collection of hole punch detritus) into the catalase solution. Ensure it is well mixed.
Remove and shake off any clearly excess catalase solution from the disc.
Drop the disc into the beaker of hydrogen peroxide from the consistent height of the top of the beaker, and start the stopwatch as soon as the disc hits the surface of the solution for the first time. Remove and discard the disc into a pre-prepared waste beaker.
If the disc settles at the side of the beaker or gest caught on the sides, remove it with the forceps and repeat that trial.
Note that the hydrogen peroxide only needs replacing when the pH is altered and should not be replaced between repeats at the same pH value
The diagram below portrays the dropping process.
Equipment List – Apparatus and Chemicals
Hydrogen Peroxide (5vol.) – 200ml
Measuring cylinders – 2 x 50ml (± 0,05ml)
Beakers – 5 x 50ml (± 0,05ml)
Syringes – 5 x 15ml (± 0,05ml)
Stopwatch – the iPhone app was used since it was deemed easier to use than the analogue stopwatches provided by the school (± 1 second)
Catalase source from liver of Ovis aries – 50ml at a concentration of 1% in 1 litre of water
pH buffer – 15ml each of pH 4, pH 6, pH 8 and pH 10
Paper discs – 25 (plus ample spare discs in case of mistakes)
Forceps – thoroughly cleaned beforehand
Safety goggles were worn throughout the experiment due to the fact that most enzymes are sensitizers, and could potentially cause breathing difficulties if inhaled. Additionally, many enzymes – such as catalase can irritate the eyes and the skin. However, due the fact that the catalase enzyme solution used was concentrated at less than 1%, it was deemed unlikely that the experiment contained any significant risk to the group
On the whole, there were no ethical considerations in the actual practice of the experiment. However, during the pilot study, the group expressed concern over the potential exploitation of the Ovis aries subject from which the liver catalase was obtained. However our teacher assured us that the lamb used had been housed in the most ethically aware institution in Britain, and that the catalase had been obtained without causing pain to the animal.
Table of Raw Data to show the time taken for the paper disc to rise at different pHs and thus the level of catalase activity at different pHs
Time Taken (s) (±1s)
Time Taken (s) (±1s)
Time Taken (s) (±1s)
Time Taken (s) (±1s)
Time Taken (s) (±1s)
Table of Processed Data to show the time taken for the paper disc to rise at different pHs and thus the level of catalase activity at different pHs
Mean Time Taken (s) (±1s)
A mean was calculated in order to incorporate all of the data values collected and to counteract the detrimental effect of anomalies. This was done using the following formula.
The mean transmission for temperatures at pH 6 for example:
(6.82 6.65 6.50 6.10 5.56) ÷ 5 = 6.33 seconds (± 1s)
The standard deviation was calculated to show how much the results varied from the mean on average (the spread). This was done using the following formula.
The standard deviation for pH at pH 6 for example:
The mean is equal to 6.726 and the sum of all deviations from the mean is 1.0172.
Hence standard deviation can be worked out by solving the following equation:
?=?(Xi– ??)2n–1= 1.01725–1
Error bar = 1 standard deviation which is different for each data point
There were no especially anomalous results exhibited
The trend of the data obtained overwhelmingly supports the hypothesis that was made. It is clear that as pH increases and decreases from pH 7, then the time taken for the paper disk to rise and fall through the hydrogen peroxide solution increases. This shows that the more pH varies from the optimum level of pH7, the less active the enzyme catalase becomes in breaking down the hydrogen peroxide, because at low and high pHs less gas is being produced at the same rate to propel the disc upwards.
For example, the two most extreme pH values at which the experiment was conducted (pH 4 and pH 10) were also the values at which the paper disc took the most time to fall and rise – 8.93s and 6.75s respectively. This contrasts directly to the amount of time taken by the disc at the optimum pH of 7 – where the average value was the much lower 4.51s. This follows the trend observed in most scientific investigations about the effect of pH on enzyme activity – and resembles the hypothesis diagram from the start of this report. The conclusion to draw from this is that enzymes require a very specific pH in order to operate most efficiently.
The results do not entirely represent the perfect trend which was hypothesized at the beginning though. It was expected that the mean time taken (s) (± 1s) for pH 4 and pH 10 would be more similar than 8.93s and 6.75s respectively, due to the fact that these two values are the same difference from the optimum pH (of 7). One possible reason for this is that the amino acids which make up the catalase enzymes are more resistant to alkaline than acidic conditions (since the time taken was longer at the lower pH) – indeed there is a good deal evidence in scientific literature that this is the case. However, the conditions in the human liver for catalase enzyme activity occur at pH 7, suggesting that due to adaptation over time, the body has determined that a neutral pH provides the very best conditions for catalase to operate under.
On the whole though, in this investigation pH clearly has had an effect on the ionization of amino acids – the proteins that make up the catalase enzyme. Acidic amino acids contain carboxyl functional groups in their side chains. Basic amino acids contain amine functional groups in their side chains. The state of ionization of the amino acids is altered when the pH is changed. If the conditions become more acidic, then due to the proliferation of H ions, the charge becomes more positive. If the conditions become more alkaline, then due to the proliferation of OH– ions, the charge becomes more negative. As a consequence of this, the hydrogen bonds that determine the 3-D shape of the protein are altered. This is known as denaturing and causes a diminishing activity level from the enzyme catalase. Changes in pH do not only affect the shape of the catalase enzyme but also change the shape or charge properties of the hydrogen peroxide substrate so that the hydrogen peroxide will not bind to the active site and thus cannot undergo catalysis.
Evaluation – Data Reliability
On the whole, the data that was obtained exhibited a good level of reliability. The standard deviation was low for all data points, with the maximum being 1.16. Hence the data was clustered around the mean, illustrating the fact that there were no wild variations. This consistency is perhaps down to the fact that following the pilot study, where we found the stopwatch quite difficult to use accurately, the iPhone app was used instead – something which enabled us to be far more precise and to obtain more reliable results. It is perhaps down to this that there were no anomalies. The number of data repeats – increased to 5 from an initial 3 in the pilot study – was perfect, both in terms of timing – which emerged as a logistical concern, but also in ensuring that a representative average could be obtained from the data.
Evaluation – Limitations and Improvements
Limitation of Experiment
Systematic (method) or Random (experimental errors)
How could this have affected the results and hence the conclusion?
Suggestion for amelioration of this problem
Beaker size not entirely consistent – since they are designed by humans, and due to meniscus effect the volume of substance in the beaker may be deceptive
This created room for error with regards to the measurements – if too much hydrogen peroxide had been used then the effect of the pH changes on the experiment would be less pronounced and would thus lead to less clear results. This is due to the fact that the human eye is not precise in analysing such measurements
Spend some more of the science department budget on mathematically produced beakers which are all precisely the same size. The meniscus effect in liquids can be overcome by using a goniometer – which is an instrument that measures contact angles
Paper Discs sank inconsistently
Sometimes the catalase in the filter paper disk reacted too quickly/not quickly enough with the hydrogen peroxide, since there had been different levels of absorption into the paper. This may have contributed to results being variable, as due to this flaw in the method it is difficult to standardise the results with the same conditions
A different measurement technique for the production of gas could be used – perhaps a gas syringe if the experiment was conducted in a different way, using different volumes and concentrations of the enzyme and the substrate
Catalase concentration varied wildly due to imprecise source (could have come from all sorts of different Ovis aries whose liver concentration of catalase would fluctuate greatly) – so difficult to be exact
Since the higher the concentration of catalase, the higher the rate of reaction, this variation of the nature of the catalase used in different parts of the lab could have caused a lack of accuracy between the sets of trials at each pH value
In the future if catalase was taken from the livers of Ovis aries that exhibit similar physical characteristics (size, age, gender etc.) or even simply from the same animal this would improve the accuracy of the results since the catalase concentration would be more consistent. The logistical and financial difficulties of this solution are, of course, noted.
Stopwatch inconsistencies remained as a result of human reaction times – despite switching to a more precise method
This would have directly affected the results – since time was being measured as the dependent variable.
Perhaps a more sophisticated or detailed system of time measurement could be used – such as milliseconds. However this does not solve the inherent (and perhaps unsolvable) problem of the delay in human reaction times. Maybe a robotic solution is the only way to eliminate this, with sensors of some sort automatically timing the journey of the paper disk as it falls and rises through the hydrogen peroxide.
Ranking of Limitations (1 = most important/significant)
Stopwatch inconsistencies – because it is the one that directly influences the final results in the largest way, given that the average human delay in reaction time is approximately 0.25 seconds for a visual stimulus.
Paper Disc inconsistencies
Beaker Size inconsistencies
Catalase Concentration inconsistencies
Bibliography – All Accessed May 2019
 Article about enzymes https://www.scientificamerican.com/article/exploring-enzymes/ (accessed May 2019)
 Article about superoxide https://www.mcgill.ca/oss/article/general-science-you-asked/hydrogen-peroxide-bodys-best-defence-system (accessed May 2019)
 Optimum pH conditions for catalase activity are said to be between pH 7 and pH 11 – https://sciencing.com/ph-levels-catalase-6826245.html (accessed May 2019)
 ‘The average reaction time for humans is 0.25 seconds to a visual stimulus’ – https://backyardbrains.com/experiments/reactiontime (accessed May 2019)
Preventing Effects of Global Warming
How can we as a species prevent the continued effects of global warming and to what extent has irreversible damage already occurred?
Global warming, also known as climate change, describes the rising temperature of the atmosphere and ocean. Throughout all of earth’s history climate has been a very fluctuate factor (for example the ice age). However if you take into account how much organisms on earth have evolved into their stable habitats and how each one depends on their habitats to survive, fluctuations will be much more harmful now, especially to humanity and the animals humanity relies on e.g. Honeybees. The main cause of global warming is thought to be the result of humanities actions, for example; Co2 emissions (from cars and other transport) interfering with the O-zone layer causing, Deforestation in rainforests (from workers creating space for cattle grazing) and Farming (many fertilizers contain nitrous oxide which is harmful to the O-zone layer, and sheep/cattle produce large amounts of methane which is also a harmful greenhouse chemical). In the century atmospheric temperature has risen ~1â-¦ F and Oceanic temperature ~0.18â-¦F (1). Whereas this may not have an immediate effect; in the future this will cause extreme weather conditions such as droughts, wildfire and mass flooding/intense rainstorms. Although to an extent we can already see this beginning to happen, for example if we look into the statistics of how many acres of land per year are destroyed by wildfire (see figure 1) we can clearly see an incline in the more recent years as Co2 emissions and temperature also increase( see fig. 2). This would make sense as dryer conditions make an easier/quicker path for fire to spread. However looking into the source of figure one we can see updated statistics which indicate a drop in the number of wildfires after this graph was made, although this could be due to human intervention and preservation methods.
As well as being a mass inconvenience for humanity these effects could also be very damaging to other species on earth, this is why scientists are focused on looking into/exploring alternative methods to try and lessen the rate of climate change. If conditions were to change too much or too rapidly many species would not be able to survive or adapt into this new climate and in relation we may see a mass bottle neck in species, or in the most extreme cases; extinction. On the other hand we may see a certain species flourish and grow in this new environment which may lead to a tip/collapse in an eco-system which would cause other species to suffer. Not to mention if climate change carries on at the rate it’s climbing earth may soon be inhospitable to humanity, our future generations.
Although scientists know global warming is irreversible there are still certain methods humanity can adapt to lessen the rate. For example scientists have been looking into alternate energy to try and encourage more people to switch from fossil fuelled energy to a more eco-friendly and renewable energy sources. 21.3 billion tons of CO2 (carbon dioxide) are produced by the burning of fossil fuels per year (2), which obviously contributes to the concentration of CO2 in the atmosphere and in turn further damages the O-zone layer but these new energy sources use natural methods which are easily replenished such as; solar energy, wind energy and hydro energy which do not produce any harmful emissions. This is obviously a great solution to lessen the rate of climate change; if more people started using these methods of energy we could cut emissions down by the masses and slow the rate of Global warming a considerable amount. These solutions are relevant in the fact that they don’t release greenhouse gases and harness natural power without any mass destruction and harm to the environment and habitat around it.
However methods such as these are expensive and aren’t as cost effective as non-renewable sources, so economically it is not the best choice, especially for poorer countries. On the other hand because non-renewable sources are coming close to running out (unless new sources/mines are found), the price for nonrenewable energy is beginning to climb higher and higher (due to less availability and more demand), which in turn (and partly due to advancing technology) basic renewable energy sources are becoming cheaper and more obtainable, for instance towns people may choose to have a certain number of solar panels on their roof due to the declining prices (see fig 4). In just one year the price for 16 solar panels to be installed has gone from £15000 to £7500 which is a 50% saving (see Fig. 3). However methods on a larger scale, for example wind farms, (to generate a substantial amount of energy) would need anywhere between a dozen or hundreds (see fig. 5). Which obviously, again, would costs a great amount and not many countries could afford them leading to more economical problems; especially since sometimes they come with instillation prices and taxes.
One environmental problem that would face the panels is in countries like the UK. The weather is extremely variable and sunlight is at its most intense in summer when less energy is needed, say for heating because the weather is warmer and for lighting because the days are longer in summer. ‘The ratio between summer and winter inputs is unfavorable’. However other countries like France and USA have a much more constant input. (3).
A social/economic problem with solar panels is that if one would want to produce energy on a larger scale the panels would need to be in a very large place with access to sunlight. These are called Photovoltaic power stations (or solar farms). The placing also contributes to how much power these panels generate; the slope of the location, the axis in which the panel is mounted on, hemisphere, ect. This of course will take up large amounts of field space that may have been previously used for farming (see fig 6) or recreation. In which case the farmer of company could see a loss in profit from the missing land (as farming can’t be done under these panels unlike wind farms) and the civilians could argue that the land is being wasted. As far as the panels effect on human life, past the implications, are next to none. However, other wildlife which may have resided in the open space before it became a solar farm will have had their habitat destroyed and would have had to migrate somewhere else, which would cause a disturbance to the wildlife.
Another implication of renewable energy is a social issue based around Wind farms, many people oppose having wind farms/ turbines around their homes/towns. Theresa Groth and Christine Vogt have done a study (4) in which they mailed a questionnaire to different town and counties to gather an idea of what the general opinion is on Wind turbines and their usefulness, many responded to the questionnaire by saying turbine placement near their residence increased uncertainty and concern of them, next to no one focusing on the positive outcomes like clean energy/no emissions. Others claim that the visual appearance of the turbines ruins the landscape. As for the actual risk to humans from these wind farms a report was published in 2007 by the U.S. National research Council (5), it concluded that although low-frequency vibrations are not well understood in their relation/effect on humans, and that of course sensitivity to the vibrations varies greatly among people, wind turbines would not be a major concern/threat to people beyond a half-mile. Of course there are still people/scientists who disagree but further research need to be done on Humans and their sensitivity to low frequency vibrations/noise. And for the effect on other living organisms beside humans; ground animals such as cattle and grounded wildlife (deer/badgers) do not seem to mind the turbines and carry on with grazing/hunting (see fig. 6). However, flying wildlife e.g. birds and bats seem to have a higher mortality rate around areas with wind turbines, presumably due to flying into the structure or spinning blades. However according to studies and surveys birds have the ability to detect the wind turbines and anyway more research shows wind turbines have not reduced bird populations so much so that there will be a noticeable effect (unbalance in the food chain/eco system.).
To get a further understanding of how the climate is changing scientists use a number of methods to obtain data they can evaluate and compare for more answers. For example the US Global Change Research Programme (USGCRP) publishes a National Climate Assessment which looks into how climate affects different regions of the US. It also observes the long/short term changes in climate and the ozone layer using satellites and monitoring icecaps melting and sea levels. It also aids scientists in predicting any future changes to the environment and if we are at risk of being vulnerable to natural disasters. For example; by studying these satellites that collect all this data scientists can observe change in conditions such as the rising of waters upstream to a village in Bangladesh. The satellite will take pictures from space and use their altimeter to measure the distance between itself and the river surface revealing the change in height of upstream locations and seeing as the data is nearly instant allows scientists to look at potential flooding risks downstream closer to the village ect. (6). This recent method of using advanced technology is much more reliable and quicker than using a ground based network, taking into account how the ground network doesn’t extend as far upstream as the satellite and information isn’t as instant as the satellite. An example of a ground based network is the Flash Flood Early Warning System which was introduced in 2013 to give warnings to locals about an upcoming flash flood. However this service only provided a small amount of warning time (~3 hours) which is a very small amount of time compared to that the satellite can provide. Although this is not a prevention method it is the best scientists can do without interfering with the local towns or river path. Which would have an effect on the locals and their crops as the water source would either be diverted or be behind flooding barriers.
An alternative method to renewable energy and a disaster forecast is the reconstruction of forests. Trees are responsible for absorbing Carbon Dioxide and converting it to Oxygen which then is released back into the atmosphere. However, in these past couple of decades deforestation has become a major industry and 12-15 million hectares of forest are lost each year (7). There are a number of reasons for this; making space for cattle farming, harvesting wood for fuel and illegal logging. This isn’t just harmful for our atmosphere but lots of animals are in danger or threatened because of their habitat being destroyed. So as an alternate method I think that scientists should look into claiming more forest as protected/private land and look into the replantation of forests where ever possible. Not to mention looking into cracking down on illegal activities in the forests (logging/hunting) and enforcing punishment. Although this may create a social implication, more so in tropical isolated regions, as some small villages believe certain animal skin to be medicine and use the wood for heat and fuel, also only surviving on cattle and crops in the spaces where trees used to grow. Perhaps another suggestion would be roof top gardens in cities, which will create space for plants to photosynthesise and exchange carbon dioxide for more oxygen. Although the building would have to approve planning permission and would take a certain amount of time to grow, and would need a lot of care I think it would be an interesting method to try and reduce the carbon concentration in the atmosphere, interfering with the O-zone layer.
Another alternate method that would greatly help with cutting humanities carbon emissions is if more people purchased and used electric cars. Electric cars do not produce tailpipe emissions and are much more eco-friendly, they have been introduced before but never really caught on as technology was lacking and there were limited charging places. Even now the battery life does not last as long as say a petrol fuelled car and the charging time takes so much longer than a simple refuel, but if scientists were to look into and experiment more with the concept and perhaps have a charging station at every petrol station people might begin to adapt to the idea and in turn lessen their carbon emissions. Although battery powered cars are considerably more expensive than the usual petrol/diesel ones, battery prices are beginning to decline, much like the solar panel prices. So maybe in the future it will catch on just as well as the panels.
Bibliography 1) http://ocean.nationalgeographic.com/ocean/critical-issues-sea-temperature-rise/ Sea Temperature Rise-National Geographic-Unknown author-Unknown date published- Date used 20/3/15
2) http://www.environmentlaw.org.uk/rte.asp?id=192 Human activities-Environment Law-Unknown author- Unknown date published- Date used 20/3/15
3) (Book) Man and The environment-Cambridge Social Biology Topics-Alan Cornwell-First published in 1983-date used 20/3/15
Because this book is quite old I can’t find much information or the book it’s self-there for I’m beginning to question its reliability mainly for the fact it’s 32 years old and a lot of advancement has been made in the past thirty years and climate and attitudes have also changed. However after lots of searching I found that the author was Head of the Science Division at Bulmershe College of Higher Education in Reading, Berkshire. It was published by the Press Syndicate of the University of Cambridge which leads me to believe that even though it is old it is accurate of its time and was valid and maybe still is valid today, as the author clearly had scientific knowledge and access to studies and information. It has lots of picture evidence as sources to back up their points and is very in depth, including diagrams of cycles and chemical equations of relevant reactions. Whilst researching and validating a table they had used in the Air pollutant section (page 37) ‘Deaths Due to Urban Smog’ I decided to research the numbers and dates to see if they were similar. Looking at figures it is clear to see they were rounded to the nearest thousand (Place: London) and again London had many more deaths than New York or Belgium, which supported the table in the book. Over all I can conclude that this is quite a reliable source.
4) http://www.sciencedirect.com/science/article/pii/S0960148113004370 Rural wind farm development: Social, environmental and economic features important to local residents-Science Direct-Theresa M. Grotha and Christine A. Vogtb- Date Published 23/9/13 –Date used 20/3/15