Save the planet

Save the planet! How? See below...

pH on the down low

Acid Rain impacts:

Computing

It has similarly been shown that NOx, even though it is not usually considered to have as much of an effect as SO2, can have impacts on indoor areas as well. With it corroding computer systems because of its reaction with Copper, Zinc and Aluminium (Oesch, 1997).

Forest Biomass

Tree Rings patterns showing growth over time

Acid rain has devastating effects on natural ecosystems as well. Forest biomass has been declining in response to increases in acid rain. Calcium and Magnesium has been lost from the soil which is needed for plant development as a result of the leeching from the acid rain, and draining of the mineral rich water (Likens,1996).

So its not just deforestation we should be worried about! Trees will continue to decline and be suffer from illnesses because of the acidification they experience if we do not cut back on our emissions!

Freshwater ecosystems

Finally, freshwater ecosystems are found to be struggling with their increased acidity as an effect of acid rain. A lot of research has been performed on the acidification of lakes in the UK because there is concern that the damage upon the ecology may be irreversible (Monteith, 2013) . Using lake cores, diatom analysis has been used to infer pH values over the years in these lakes. The aim of this has been to attempt to estimate a pH value prior to the impacts of acid rain from anthropogenic emissions, and use it as a target to restore the lakes to their natural conditions(Battarbee,2008).

Dying fish as a result of acid rain

It has been observed in the cores that there has been a significant decline in the concentration of Sulfur from mid-1990s onward (Monteith, 2013)! This is greatly encouraging, however the impacts on the lakes has not been as noticeable or dramatic. A spatial variation is observable across the UK, with the initially most acidified sites responding the fastest and increasing their pH, whereas others haven't as much.  The magnitude of the impacts have been correlated with the availability of Carbon and whether the site has been afforested. This is because water with a higher pH has a higher solubility to organic Carbon (which has positive impacts on the lakes ecosystems).

So the good news is; pH is decreasing as a result of a successful reduction of emissions. 

Bad news; Concentrations of Sulfur and Nitrate remains abnormally high in relation to post industrial levels, so restoration must continue, and emissions must continue to drop to reach target levels. 

Battarbee et al, 2005, interestingly mentions that the rapid climate change we are experiencing may mean that we need to alter our target levels of restoration as conditions change, as those targets may no longer be feasible. Increasing atmospheric temperatures will lead to increased surface water temperatures, which will decrease their solubility of Oxygen, which impacts all living organisms. 

Climate change has impacts on everything apparently...!

Let it rain! ... or not!

Location of the Acropolis

Being born and raised in Athens, Greece, I grew up hearing all about the Acropolis and its history. Located in the centre of Athens, high on a hill so it can be seen from most of the city centre, but therefore also located in, currently, in the most polluted area of Athens. As a child I was surrounded by people who spoke so passionately about it and how proud they were that even though Greece's reputation might of been dispirited (due to the economic crisis) they will always have their history to be proud of. A history which nobody can take away from them.. OR CAN THEY?

The Parthenon

Acid rain is a world wide problem. Since the industrial revolution, pollutants have been emitted into the atmosphere at an accelerated rate, especially Sulfur(SO2) and Nitrous Oxide(NOx). These acidic compounds  are sourced from natural sources such as volcanic eruptions and lightning respectively, but its the atmospheric emissions which have caused abnormal amounts to persist in the atmosphere and mix with the atmospheric H20. When they mix with water particles in the atmosphere they decrease its pH. Thus, in effect, when the water particles precipitate they have a much lower pH than normal. This acidity can have very damaging effects on various human and environmentally constructed components on the planet. Rain in areas far from industrial sources and hence their pollutants is known to have on average a pH of 5(Schindler, 1988). Any pH lower than this will start reacting with materials and causing damaging effects.

Anthropogenic sources include electric power plants and vehicles. Production of electricity is however the major source. Many techniques to prevent these effects have been tried but not many have been successful. For example, making the smoke funnels taller, but that unfortunately resulted in the smoke being able to travel even further! Therefore, policies had to be implemented worldwide, but the US and Europe were particularly successful in reducing their NOx and SO2 emissions over several decades (Figure 1). Luckily this also correlated with a decrease in acid rain and a noticeable recovery in lakes and streams (EPA). Hence, the only truly successful measure that can be implemented is to reduce emissions;

Which is one of the reasons you are told to "TURN OF THE LIGHTS when you aren't in the room!"

Figure 1: Total Sulfur Emissions over time

The parthenon has 'semi' survived the effects of bombs, fires and earthquakes! Could a little big of rain really be enough to destroy it forever? The parthenon is made of beautiful white marbles (essentially limestone), and it is now turning black and being corroded!! This is not only because of the acid rain reactions but also because of the black fumes coming out of vehicles (but this is a matter for a different day). The question is how to preserve the sculptures as best as possible without losing the incredible detail (Figure 2)? Limestone is very sensitive to acidity, which corrodes it very productively (Kucera,1994). Therefore as discussed above the only guaranteed ways of reducing these effects is for the Greek government to either enforce policies which will reduce the people total electricity usage, or to implement alternative energy sources other than fossil fuels which do not pollute the atmosphere. 

Figure 2: Battle of the centaurs, depicted on the metopes of the Parthenon

Currently, they are attempting to clean as much of the monument as they can using laser treatment which combines UV and Infrared beams (Daily Mail, 2008) Figure 3 below, shows the effects of the treatment on the marbles( left side is cleaned, right side is still black). But this only works in reducing the effects of smog, and not the effects of corrosion. Once the marble is corroded it is lost forever.

Figure 3: Cleaning using the laser technology.

The parts from the Acropolis temples which have been taken into museums (Acropolis museum, Athens and British museum), have parts missing due to the damage of the earthquakes and of the bomb. New marble has hence been replaced to fill in the gaps. This however not only looks artificial, as the new marble is so much whiter than the ancient one, but the detail can not be replicated. Therefore, the only solution for the corroded marble in the future will be to do the same which will eventually lead to more of it being replaced and the genuine history being lost.

So, in the future, to save the history of Athens, either all of the acropolis will have to be taken apart and placed in the protection of museums, or there will have to be a significant reduction in the amount of pollution emitted in Athens.

Anthropocene

Natural variability or new epoch- The Anthropocene?

What's all the fuss with Polar Stratospheric Clouds?

Why is the ozone hole above Antarctica when it is the developed countries in the Northern Hemisphere which use the highest concentration of CFCs? The answer is Polar Stratospheric Clouds!!

Without Polar Stratospheric Clouds

Incoming UV radiation breaks down chloroflurocarbons. This results in either ClO (Chlorine Monoxide) which has reacted with ozone or as Chlorine atoms (Cl). Subsequently, naturally occurring gasses such as Nitrogen dioxide and methane react with ClO and Cl to form chemically inactive molecules (CIONO2 & HCI) Shown in Figure 1. The reaction then ends, therefore ozone depletion is minimal.

Comparing reactions in the presence of polar stratospheric clouds and their absence.

With Polar Stratospheric Clouds

Contrary to the above conditions where there are no polar stratospheric clouds(PSCs) present, when they are, the reactions occurring are very different. PSCs initiate reactions between the two reservoirs which withdraws Cl from its reservoirs in the form of Cl2. Sunlight will then break up molecular Chlorine (Cl2) into separate Chlorine atoms which are highly reactive with ozone. This reaction then forms ClO & O2, which rapidly react with each other giving off producing Cl2O2 which in the presence of visible light will break down into Cl atoms and Oxygen molecules. 

Reservoirs are not reformed because of the precipitation of Nitric acid which prevents them from occurring. 

The hole problem

The formation of ozone requires ultraviolet radiation and a reaction with dioxygen. Shortwave UV radiation hits oxygen molecules and breaks them up. These now unstable oxygen atoms will latch onto other oxygen molecules creating O3 (ozone). The formation of ozone therefore requires UV radiation. It is therefore ironic that UV radiation (which helps to create ozone) is also prevented from reaching the atmosphere by ozone's' absorbing action. UV radiation is not tolerable by plants, animals or humans. Its wavelength is too short and strong for plants and animals to deal with and thus humans are more susceptible to skin cancer if they often in strong exposure to UV rays. The survival of man kind and ecosystems is therefore highly dependent on the presence of ozone in the atmosphere (stratosphere) to block incoming radiation.

Ozone has undoubtedly been present in the earths atmosphere since the beginning, as life on earth can not have existed without incoming UV radiation been absorbed and preventing damage to ecosystems. It has forever been regenerating and being destroyed, by naturally occurring chemicals such as Hydrogen, Bromine and Nitrogen (Solomon, 2010). These chemicals trigger catalytic reactions which break down Ozone into Oxygen and other elements. This has kept ozone levels fairly steady throughout the years, with these elements having naturally occurring variations which were in no way extreme.

Chlorofluorocarbons(CFC's) are created by humans for use in refrigerators, air conditioners and other uses for maintaining temperature. Therefore, did not come into existence until the 20th century. Chlorine atoms are very reactive and leads to one of the reactions which destroy ozone(Solomon et al, 1986), and when CFC's are expose to UV radiation they dissociate and form chlorine atoms which are highly reactive with ozone, diminishing it to Oxygen molecules and ClO (Chlorine monoxide which also reacts with ozone) - do you see the vicious cycle?

The polar vortex creates a beautiful but catastrophic phenomenon called polar stratospheric clouds. As clearly explained by the name, they are present near the poles, especially during their winter, where there is no sunlight for approximately 3 months which means that temperatures reach record lows of -80 degrees Celsius (Poole,1998). It is the conditions present on these clouds which are perfect for the photochemical reactions leading to the break down of ozone. Therefore, the period that this ozone destruction occurs is in the early spring of the antarctic, when there is just enough sunlight for the radiation of UV to be enough to trigger the photochemical reaction which lead to the breaking down of ozone but not enough to melt the clouds and stop the reaction. The presence of the polar stratospheric clouds are why ozone in this area is being depleted so rapidly, and not in other areas (explained in my next blog).

Figure 1: Polar Stratospheric Clouds

Even though the antarctic polar vortex confines the depletion of ozone within the area of circulating cold air around the continent(Toon,1991), when the clouds have melted and the reactions are terminated, warm air from lower latitudes intrudes, and the depleted ozone air blows towards the equator, and usually is focused above Australia, and specifically Brisbane(Solomon,2010). The location of Australia near the equator means that not only is there less ozone for the suns rays to travel through, and therefore less is absorbed or reflected, but the sun in this area is also overhead, which is why these areas are at the highest risk for skin cancer (Cancer.org). 

Figure 1 (EPA,2010)

Contrary to Carbon Dioxide, Ozone concentrations have been observed to have decreased (Figure 1) over the years, and especially since 1980, when CFC use will have started to become very popular. Therefore the negative correlation between CFC's and ozone show us how strong the anthropogenic impact on a crucial element of the earths atmosphere has been.
Just like so much effort is put into decreasing anthropogenic emissions of Carbon Dioxide, it is just as important to minimize CFC usage.

Atmospheric Ozone is a crucial element to the atmosphere. It absorbs UV radiation which can have extremely damaging effects on plants, animals and even humans as mentioned previously. Skin cancer, cataracts and destruction of crops are only a few of the devastating effects that high UV radiation can have. 

Figure 3: CFC free labels from around the world

Care about the Aussies?
Care about the environment?
Look out for the CFC free labels!