Water Pollution and Mining Industries
Water Pollution
Encylopedia Britinnica defines “Water pollution is the release of substances into subsurface groundwater or into lakes, streams, rivers, estuaries, and oceans to the point where the substances interfere with beneficial use of the water or with the natural functioning of ecosystems. In addition to the release of substances, such as chemicals or microorganisms, water pollution may also include the release of energy, in the form of radioactivity or heat, into bodies of water.”
Water is an essential component of life. Of all the water present on Earth, only about 1% is available as freshwater and can be exploited by humans. Rapid growth of civilization has posed great threat to purity and availability of freshwater. Human health is adversaly affected by polluted drinking water. In the developing countries, about five million children die due to unhealthy drinking water supply. This situation is getting worse each day due to population growth. In Pakistan, according to estimates, 30% of all diseases and 40% of all deaths occur due to poor water quality. The main cause of waterborne here are the addition of municipal sewage and industrial wastewater to drinking water supply.
Sources Of Water Pollution
Water pollutants are released from two sources; point sources and dispersed sources. A point source is a pipe or channel, mostly used for to discharge waste from an industrial facility or sewerage system. The dispersed source is a open, broad, unused area from which pollutants get to the water body, for example runoff from agricultural lands. Point sources of water pollution are easier to control than dispersed sources because of its being present in a single place. It can be treated. On the other hand, pollution from dispersed sources are hard to control. There has been much development in cities sewerage system building but pollution control is still a major concern.
Mining
Mining is defined by Encyclopedia Britinnica as “Mining, process of extracting useful minerals from the surface of the Earth, including the seas. A mineral, with a few exceptions, is an inorganic substance occurring in nature that has a definite chemical composition and distinctive physical properties or molecular structure. Mineral deposit designates a natural occurrence of a useful mineral, while ore deposit denotes a mineral deposit of sufficient extent and concentration to invite exploitation.”
Mining has played an integral role in the development of civilizations. However, it also has left a negative legacy which has influenced our perception of it. Materials extracted from a mining source are about 95% wastes. These waste are left behind and can impact the environment in many ways.
Surface Mining
It has been estimated that more than two-thirds of the world’s yearly mineral production comes from surface mining. Three most common types of surface mining are open-pit mining, strip mining, and quarrying. Each type differs from the other in location of mining, mining techniques used and the types of minerals extracted.
Underground Mining
Some ore body lie at a considerable distance downward the surface, the amount of soil and other unwanted materials or waste has to be removed so to get to the ore are done by underground techniques. The negatives of underground mining are the costs, which could possibly be much higher than surface mining.
Placer Mining
Placers are unconsolidated deposits of detrital material containing valuable minerals. They form from the action of natural processes of chemical weathering to stream, marine, and wind action. Common minerals extracted in placers mining are gold, tin, platinum, diamonds, iron sands, gemstones, and abrasives; minerals of high specific gravity and physical hardness due to their chemical composition.
Mining plays a very essential role for human life. Human development is mainly measured by its technological advancement in mining and metallurgy: human life moved through the Stone Age to Bronze Age, and much later into the Iron Age. The industrial revolution was linked with growth in coal, copper, iron and tin mining; the Atomic Age was partially determined through progress in how to mine and isolate radium, uranium and other radioactive mined materials. Smartphones – the symbol of our post-industrial period- could not exist in portable form without tantalum. This all has only been possible because of mining.
About 5000 years ago, Pharaohs had mining excursions to the isolated Sinai with thousands of miners, troops, engineers and managers. Engineering complexity was developing in Spain long ago in some 2000 years ago, Romans sourced river water 60 miles from gold mining complexes for extensive hydraulicking in the Rio Tinto area, exploiting resources which had been developed by Iberians and Phoenicians over previous millennia. These operations which were ought to raise environmental controversies and criticism were developed ages ago, including not only hydraulicking but also extensive stripmining in Sussex during Roman times, metallurgical extraction using highly caustic materials, and harsh labor practices such as slavery in Cornwall.
In the 1950s, residences of the industrial town Minamata, Japan suffered many deaths and disease which were attributed to eating fish contaminated with mercury from the nearby chemical factory. In the 1960s the metallurgical industry was severely blamed for its SO2 emissions. Environmentalism movements saw a rapid growth during 1960 to 1970. People become more aware of the diverse affects of industries. The situation turned intolerable and authorties had to shut many plants and make rules and litigations to control pollution. Once the symbol of progress, was now seen as a disaster by masses.
Mining Industries and Water Pollution
Mining activities affect health via water through: the method of extraction (for example health effects on children of panning for gold in the Amazon or use of cyanide to leach heavy metals); contamination of local water sources, as well as having harmful effects on the environment such as beach erosion from sand mining or by longer term effects on reducing biodiversity or fish populations. The health effects may be far away from the mining source, as demonstrated in studies of methylmercury poisoning in the Amazon: mercury levels in head hair were studied in residents of three fishing villages on the Tapajos River, an effluent of the Amazon, several hundred kilometres from the gold mining areas. Many had high mercury levels in addition to symptoms suggesting neurotoxic disease. Further, 0.064 ppt is the EPA recommended surface water human health criterion for waters inhabited by fish for human consumption. Consumption of contaminated fish is one of the major routes of human exposure. While there have been improvements to mining practices in recent years, significant environmental risks remain. Negative impacts can vary from the sedimentation caused by poorly built roads during exploration through to the sediment, and disturbance of water during mine construction. Water pollution from mine waste rock and tailings may need to be managed for decades, if not centuries, after closure. These impacts depend on a variety of factors, such as the sensitivity of local terrain, the composition of minerals being mined, the type of technology employed, the skill, knowledge and environmental commitment of the company, and finally, our ability to monitor and enforce compliance with environmental regulations. One of the problems is that mining has become more mechanized and therefore able to handle more rock and ore material than ever before. Therefore, mine waste has multiplied enormously. As mining methods are developed to make it more profitable to mine low grade ore, even more waste will be generated in the future.
Types of Water Pollution from Mining Industries
There are four main types of water pollution resulted from mining industries
Acid Mine Drainages
One of the major source of water containment is Acid Mine Drainage (AMD) or Acid Rock Drainage (ARD). Acid rock drainage is also linked to high total dissolved solids (TDS), high sulphates and heavy metals; manganese, iron, nickel, and cobalt. AMD mostly occurs at mining sites. Rock containing sulphide minerals excavated from mines create sulphuric acid by reacting with water and oxygen. This process gets accelerated by a certain naturally occurring bacteria Thiobacillus Ferroxidams when water reaches a certain degree of acidity. Acid would leach from rock as long as it is exposed to water or air. It gets into drinking water supplies. It affects water quality and pose sever threat to acquatic life.
Among many mine waste problems, acid mine drainage is the hardest to deal with. It degrades both surface and groundwater quality. It posses a long term pollution containimation as release of AMD would continue even after mines are closed. The production of AMD usually, but not exclusively – occurs in iron 619 sulfide-aggregated rocks. Although this process occurs naturally, mining promotes AMD formation simply by increasing the quantity of sulphides exposed.
Releases of AMD have low pH but high electrical conductivity with increased concentrations of toxic heavy metals. AMD also affects soil quality, pollute aquatic sediments and fauna, and releases heavy metals in the environment.
AMD follows the same flow pathways as water; best way to control AMD is by controlling entry of water in affected sites, prevention of hydrological seepage into the affected areas and controlled placement of acidgenerating wastes. Under-drains can be installed in locations of the dumps, and the infiltration by meteoric water can be further retarded through the use of sealing layers.