Groundwater is less susceptible to bacterial pollution than surface water, as the soils and rocks it flows through screens out most of the bacteria. However, it is an excellent solvent; which means it can dissolve a lot of the minerals/gases present in these rocks or trapped between various layers.
‘The underground drought’ is to a large extent an issue of groundwater getting contaminated and becoming unfit for human use. The contamination could be natural or pollution induced by human-activities.
Pollution of groundwater is not easily reversed. If a river gets polluted, the next big flood can flush out the dirty water, sweep it downstream and into the sea. With groundwater, comparable flushing processes take much, much longer. In fact, contamination of aquifers is in most cases either irreversible or too expensive to treat.
Globally, groundwater quality issues vary greatly, as the kind of rocks, minerals and human activities vary across regions. For this reason, and because groundwater across the world has not been mapped well enough, it is difficult to paint a comprehensive global picture. Here are some well-known, widely reported issues:
Saline intrusion: With Climate Change and rising sea levels, the saline sea waters are pushing harder and harder to infiltrate onto the land and into our aquifers. Human activities (such as sand mining or over extraction of groundwater in coastal areas) are accelerating the process. Besides, deep-seated old saline groundwater always tends to penetrate through leaking aquitards.
Apart from making groundwater unfit for human consumption, salinization also affects its urban and industrial value. It can also rise up to the surface and salinize the soil, bringing down its agricultural productivity.
Fluoride: The origin of Fluoride in groundwater is mostly natural. A certain amount of Fluoride in the water (0.5 mg/L to 1 mg/L) is good for healthy teeth and bones. However, when consumed in higher concentrations, it can cause dental or skeletal fluorosis. This means discoloration and deformity of teeth, pain and damage to bones and joints (see image to the right).
It is possible but expensive to treat high-fluoride water. This means that fluorosis is a bigger problem in low-income areas. So while its incidence is much wider (see map below), it is a serious problem the Argentinean Pampas, Chile, Mexico, India, Pakistan, the East African Rift, and the Tenerife islands. Recent studies recommend that efforts to manage the issue in these areas needs to include developing and utilizing the available low-fluoride sources.
|World distribution of major reported occurrence of high fluoride contents in groundwater,
above drinking water standards Source: GroundwaterGovernance.org
- Fluoride in Groundwater: A British Geological Survey primer: http://www.bgs.ac.uk/research/groundwater/health/fluoride.html
- Fluoride in Groundwater Worldwide: Reports by International Groundwater Resources Assessment Report: http://www.un-igrac.org/publications/147#
- Fluoride-related videos on TheWaterChannel: http://goo.gl/JPbi0c
Arsenic: Arsenic is widely dispersed in rocks and sediments, occurring naturally or as a result of deep aquifer development. Consuming water with high arsenic levels (50 μg/L to 10 μg/L) causes severe harm to the body.
Symptoms of “arsenic poisoning” include diarrhea, vomiting, blood in the urine, cramping muscles, hair loss, stomach pain, and convulsions. It is also known to cause keratosis (growth of keratin on the skin, see picture to left) heart diseases, cancer, strokes, respiratory diseases, diabetes and night blindness. The symptoms have been known to aggravate and cause death.
Treating high-arsenic water is expensive as well, too expensive to be affordable by poorer communities. Drilling shallower or deeper wells may avoid the problem for some time, but this solution is costly as well, as it needs detailed monitoring of the concentration of supply wells. A 2007 study found that over 137 million people in more than 70 countries could be affected by arsenic poisoning of drinking water.
World distribution of major reported problems of arsenic content in groundwater at concentrations higher than 50 μg/L (Smedley, 2008; Margat and van der Gun, 2012)
- Arsenic contamination of groundwater: A British Geological Survey primer: https://www.bgs.ac.uk/arsenic/
- Arsenic in Groundwater Worldwide: Reports by International Groundwater Resources Assessment Report: http://www.un-igrac.org/publications/142
- Arsenic-related videos on TheWaterChannel: http://goo.gl/pJcbpo
Industrial pollution: In 2003, residents of Plachimada village in India’s southern Kerala state protested that “their wells had dried up because of the over exploitation of groundwater resources by the neighbouring Coca-cola plant. They complained that they now had to walk nearly five kilometres twice a day to fetch water. They also argued that the little which was left was undrinkable and when used for bathing the water burned their eyes and lead to skin complaints” (source: righttowater.info)
“When industries are forbidden from releasing their wastewater in surface streams, they tend to pour it down deep tubewells. This solves the problem of pouring toxic effluents where you can see it.... but it irreversibly damages aquifers,” said Chicu Lokgariwar from India Water Portal, explaining what happened in Plachimada and cautioning that it was not a one-off case.
Thousands of miles away in the United States, the energy industry has been at loggerheads with activists, academicians and affected citizens over hydraulic fracturing. Better known as fracking, it is the process of drilling down into the earth before a high-pressure water mixture is directed at the shale rock layer, to release gas and oil trapped inside. The technique involves carcinogenic chemicals that can escape and contaminate the groundwater around the fracking site.
A 2013 report estimates that in 2012 alone, the country’s 82,000 fracking wells had generated 280 billion gallons of wastewater (apart from causing other forms of environmental damage). This has heightened circumspection against fracking across the world- especially in Canada, continental Europe, South Africa, United Kingdom and Tunisia where the technique was later employed or proposed.
Industrial pollution of groundwater obviously comprises of a variety of instances, mechanisms and characteristics, representing specific cases from across the world. However, a demarcation needs to be made between other and those where industries deliberately flout rules for short term gains. Apart from technical fixes like cleanups (if possible), such cases require legal, judicial and governance-level solutions. Willingness to implement them perhaps requires a greater appreciation of the value of groundwater as a natural resource.