Water has been essential to man and nature since the beginning of time. It sustains life. It is a most remarkable non-destructive molecule. It can exist as a liquid, a vapour and a solid (ice). It can change between the three states readily and it is this ability that makes it so unique. On heating water turns to steam (vapour) and on cooling the steam returns as a condensate (water). On freezing it turns to ice and on thawing the ice it returns to water.
Refer to Fig. 1 – Water Cycle
The water the Romans of old drank is the same water we drink today. The only difference is likely to be the contaminants in it as a result of industrial pollution.
Water covers almost 70% of the earth’s surface, most of it occurs in oceans, the balance in rivers, lakes and subsurface reservoirs.
As water goes through its cycles (liquid, vapour and solid), it picks up impurities which reflect the composition of the atmosphere and that of the earth’s crust. Before reaching the ground, rainwater can dissolve gases and soluble matter and absorb insoluble matter contained in the atmosphere. This water can be saturated with dissolved oxygen, contain carbon dioxide and be contaminated with such industrial gases such as sulphur and nitrogen oxides. There has been an increase in the acidity of water due mostly to the formation of certain of these gases.
Scientists have discovered that the quality (purity) of water can be captured and be reflected by ice crystal analysis.
Picture 1 crystal formation is from a clear mountain spring water whereas picture 2 is from a municipal supply water. Notice the angles of crystal structure. In picture 1 they are at 60º and in picture 2 at 90º.
The purer the water, the closer to 60º. It is now possible to establish from high magnification photography the extent of water contamination.
High quality spring water, primarily structures angled at 60º
Poorer water quality, primarily structures angled at 90º
Sulphur dioxide (SO2) can be removed from the air by rain in which it forms a weakly acidic solution of sulfurous acid which is commonly referred to as “Acid Rain”. The acid rain results in damage to old buildings and marble statues in cities. The calcium carbonate present in the buildings and in the marble is ‘dissolved’ by the acid rain. Even more devastating are the effects of acid rain on forests and the aquatic life forms in rivers and lakes.
The pH of unpolluted rain water is usually > 6.0 but the pH has been known to drop to 2.2 above some major cities, consequently the damage to the environment and statues etc.
The reaction of water vapour and carbon dioxide (CO2) in the atmosphere can form a dilute carbonic acid (H2CO3). In extreme conditions acid rain can also leach aluminium from the soil into the ground water (subsurface) as well as into lakes and rivers. Not only do small concentrations of aluminium poison fish but they also threaten the aquatic life at the bottom of the food chain. Eggs and larvae are particularly vulnerable. The aluminium leachant can also poison plants and tree roots.
Besides aluminium there are several other compounds in the earths crust which can be dissolved by water flowing over it or percolating through it. Table 1 lists the first eight elements in various compounds that account for over 98% of the composition of the earths crust. Several of these compounds (limestone, dolomite, iron and manganese) are only slightly soluble in water. However, they are solubilised by carbonic acid which forms when carbon dioxide dissolves in water.
|
Composition of the |
||
| Element | % | |
| Oxygen | 46.43% | |
| Silicon | 27.77% | |
| Aluminium | 8.13% | |
| Iron | 5.12% | |
| Calcium | 3.63% | |
| Sodium | 2.85% | |
| Potassium | 2.60% | |
| Magnesium | 2.09% | |
Surface waters are usually saturated with dissolved oxygen and contain only a small concentration of dissolved carbon dioxide because the surface water is in equilibrium with air which contains approximately 21% oxygen and an average of only 0.03% carbon dioxide. In contract, subsurface waters may contain substantial amounts of carbon dioxide, methane and hydrogen sulphide gases.
It is the dissolved oxygen in water that sustains aquatic life. At sea level the concentration of dissolved oxygen is approximately 14mg/ℓ (14kg per one million litres) whereas in Gauteng the concentration is approximately 8mg/ℓ (8kg per one million litres).
Acid rain is a source of concern because of the harm it causes, but for those of us living in Gauteng and also to the east and west of it, the subject of Acid mine Water (AMD) appears to be a far greater immediate threat to our environment and our water resources. Experts predict that the very poor quality water could surface in eighteen to twenty four months in parts of Johannesburg and on the East Rand. The risk is that it will cause damage to the foundations of structures and also contaminate water streams and the environment in general.
The cause of the potential crisis can be attributed to mining activities stretching back over 100 years and the subsequent closure of old worked-out shafts without there being a proper mine closure procedure implemented.
Mining activities exposed certain heavy metals such as sulphur and uranium that are locked in the earths rocks. Mine service water gets recirculated and is re-used. The water is used for dust suppression, spraying after blasting, environmental cooling of the hot underground conditions and washdown to recover the fine gold particles. The water reporting to the drains and pump chambers is usually acidic as a result of the leaching of pyrite (rich in sulphur). In recent years the operating mines practice acid water neutralisation to minimise ‘acid mine water’ discharge to the environment.
Why are people worried about it?
The reason people are worried about this water is because of the risk it may enter the source of the drinking water supplied to us by Rand Water or other recognised water providers.
The other concern even though this doesn’t go into our drinking water, it gets pumped into mines and dams that supports plants and aquatic life. The aquatic life is also hugely affected. If the water that the fish live in is contaminated the fish will also absorb the heavy metals by eating contaminated water plants and micro-organisms. The big problem comes when people end up eating these fish. The plants next to the river may also be contaminated by the water. Land or aquatic animals usually end up eating these plants. In many cases these animals serves as a food source for humans. A heavy metal such as uranium can also be transported to vegetation by water. It can either be deposited directly onto the plants or absorbed out of the ground. This isn’t a once off problem. The uranium is absorbed into the ground, which means that whatever is planted next will also absorb the uranium.
The primary human organ that is at risk with exposure to uranium are the kidneys. Long term exposure and intake of high levels of uranium may result in irreversible and progressive renal injury.
Is something being done about this?
Yes. Mines were directed to conduct a comprehensive investigation in order to determine the full extent of the radioactive contamination developing because of mining operations and provide a report to the National Nuclear Regulator. Review and update environmental monitoring plans. Provide a schedule to review and update the Public Hazard Assessment of the mine, taking into the account the leading pathways as identified through study. Restrict access to animals and the public or use of water for irrigation purposes to the identified sites, while further investigations were being carried out.
Why mining needs to continue?
Mining contributes to a large chunk of South Africa’s economy. It might not be the biggest part of our economy, but it’s one of the most consistent and it plays a big role in manufacturing and the retail trade. Normally when people think about mining, the first thing that comes to mind is jewellery like , beautiful rings, shining earrings and sparkle necklaces and diamonds.
Unfortunately all mines, platinum, coal, iron ore and gold creates the problem of “acid mine water”. But if you just take one of these like gold for example you’ll see why South Africa needs to continue mining and why it’s far more than just a symbol of riches and an object of desire.
Gold is used in many different ways that might amaze you, for example in electronics like calculators, television sets, cell phones and in computers. It’s in the motherboard of your computer. Gold is used to make the connectors in most electronic components. It’s a very good conductor of electricity. Just try to imagine life without your cell phone , or computers. These days almost everything is done with computers.
The reason why gold is used in so many products isn’t only because of its conductive properties, both copper and silver are far better conductors and much cheaper. It’s used for its resistance to corrosion. If there were a cheaper alternative people would surely use it. Gold is also used in aerospace technology because of its special properties.
Gold is used as a lubricant in space crafts. In space the radiation is much more than on earth and in a vacuum, organic lubricants are useless. It is used in the circuitry, one again because it’s a good conductor. Gold-coated polyester film is used to help to reflect infrared radiations, and to stabilize the temperature within the space craft. The visor of an astronaut’s helmet is covered with a thin coating of gold to reflect the intense solar radiation to protect their skin and eyes.
Gold can be used in treatment of certain medical conditions as well as in their diagnosis. It can be used in cancer treatment by planting very small particles of radioactive gold into the effected tissue. Gold is non-allergic and is therefore safe to use as orthodontic appliances, crowns and fillings. There is a condition known as Lagophtalmos, where the Person suffering from this is unable to close their eyes, a very small piece of gold can be planted into the upper eyelid to enable the person to close his eyes. It has also proven to be very effective in the treatment of gout.
Gold is also used in glass making, and it is also used in the windows of climate controlled buildings’ to reflect solar radiation outward and to help keep the buildings cool.
Gold has always been associated with status, and purity, which is also why gold is used for the making of religious symbols, gold can be beaten into very thin sheets that can be applied on many different surfaces.
In the picture below a Taiwanese scientists research shows that the leaves mixed with nano particles of gold and water causes chlorophyll in the leaves to produce luminescene which is claimed as researchers to be an energy-saving replacement for street lights.