Heavy Metals in Water Resources
Heavy metals are the metallic chemical elements which have high density and high amounts of poisonous or toxic substances at low concentrations (Afzal et al, 2013). Cadmium, arsenic, thallium, lead and cadnum are some of the metals listed among heavy metals and they usually get into the human body via drinking water, food and air. Some of the heavy metal elements are useful in maintaining metabolism in the human body and these include selenium, copper and zinc. However, these metals can become poisonous when in high concentrations. For instance, one can develop poisoning from drinking contaminated water that is passed through lead pipes, a food chain or high ambient concentrations of air. This essay thus seeks to discuss both the natural and artificial sources of heavy metals while highlighting the impacts of heavy metals on health and the environment. In addition, it will address the accidents that are related to the heavy metals and associated with the contamination of water resources.
Natural Sources of Heavy Metals
Heavy metals can occur naturally as a result of the physical and chemical weathering of metamorphic and igneous soils and rocks which also release the metals into the water resources. Heavy metals can also be generated from the plan decomposition and animal atmospheric deposition of the airborne particles that come from wind erosion, volcanic activity, plant exudates, oceanic spray and forest fire smoke. Heavy metals that are found within the geological structures of the earth can penetrate and exist in water resources via natural processes. For example, flowing water or heavy rains tend to percolate/leach heavy metals out of the geological formations (Ardau et al, 2006). Such processes are worsened when the geology is upset by economic activities such as mining because these processes expose the mined area to air and water hence causing adverse effects like acid mine drainage (Wyk, 2012).
Man-Made Sources of Heavy Metals
Heavy metals found in water resources can also be man-made whereby the metals permeate the water supply through consumer or industrial waster or via the acidic rainfall breaking into soils hence releasing the metals into the water bodies such as lakes, rivers, groundwater or streams. Urban storm water runoff always contains metals from roadways and atmospheric fallout while wastewaters also carry poisonous heavy metals into the aquatic system and soil through diverse processes, and in particular, irrigation. Metal-containing solids found in polluted places can also be produced from a wide array of artificial sources that are associated with metal mine stakeouts, lead-based paints, leaded gasoline, fertilizer application, and discarding the densely concentrated metal wastes within unsuitably protected animal manures, landfills, sewerage sludge, coal combustion remainders, and petrochemicals, among many others (Afzalet al, 2013).
Environmental and Health Effects of Heavy Metals
Heavy metals can adversely affect the environment hence destroying the aquatic organisms. According to Rai (2008), such destruction can be attributed to the poisoning caused by metal sediment composition and water chemistry within the water system surface. High metal concentrations in water affects the aquatic organisms in the sense that it transforms their morphological tissues, suppresses their development and growth, while altering their chemistry and leading to poor swimming performance. Aquatic plants are also affected because they cannot successfully control the metal uptake.
Ingesting heavy metals via contaminated water can also pose great health risks to human beings. Lead, for instance, can also act as a substitute to calcium especially among children taking into consideration that they need high levels of calcium to develop their skeletal systems. Even though the levels of lead contained in bones are not harmful, high concentrations can cause neurotoxicity, nephrotoxicity and hypertention (Afzal et al, 2013).Cadmium on the other hand can interfere with the ability of metallothionein in monitoring copper and zinc amounts within the human body. Mercury canalso pose a great health risk to humans because when it comes into contact with water it tends to be by the microorganisms, taking the form of poisonousmethyl mercury. Acute poisoning symptoms caused by heavy metals are exhibited through vomiting or other symptoms and chronic poisoning can cause neural damage, liver damage or teratogenenisis. Arsenic in particular can cause one to vomit, experience cardiac abnormalities, and diarrhea while chromium has been linked to adverse health effects such as respiratory and dermatological problems (Afzal et al, 2013).
Accidents Linked to Heavy Metals Contamination of Water Resources
Many regions have suffered heavy metal-related accidents and one of the major examples is the 2005 adverse environmental disaster which happened on Songhua River after a chemical plant explosion within Jilin City hence contaminating the river with about 110 tons of heavy metal pollutants (Gleick, 2009). As a result, the contamination flowed downstream and compelled the authorities to carry out temporary suspension of the water supply to an estimated 4 million people living in Harbin. Another example is linked to the November 1986 ‘Sandoz chemical spill’ in SchweizerhalleSwitzerland. The accident led to the release of toxic agrochemicals that contained heavy metal (e.g.mercury) into the air while massive tons of pollutants were simultaneously released into Rhine River, turning it red. The contamination resulted in massive mortality of wildlife downstream that subsequently destroyed a huge proportion of European eel population within the Rhine River (Halfon & Buggermann, 2006).
This essay has given a discussion of the various sources of heavy metals in water resources and demonstrated that such metals can cause grave danger to human health and the environment. It has also given examples of accidents that are related to water resources contamination through heavy metals.
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Ardau C., Concas A., Cristini A., Zuddas P., & Cao, G. (2006). Mobility of Heavy Metals from Tailings to Stream Waters in a Mining Activity Contaminated Site. Chemosphere, 63(3):244-253.
Gleick, P. (2009). China and Water. The World’s Water, 1(1):79-100.
Halfon, E., & Buggermann, R. (2006). Environmental Hazard Ran king o f Chemicals Spilled in the Rhine River in November 1986. Acta Hydrochimica et hydrobiological, 17(1):47-60.
Rai, K. (2008). Heavy Metal Pollution in Aquatic Ecosystems and its Phytoremediation using Wetland Plants: An Eco-Sustainable Approach. International Journal Phytoremediation, 10(2):133-160.
Wyk, C. (2012). Heavy Metal Pollution of Water Resources-Causes and Impacts. Retrieved from http://sustainableproductivity.blogspot.com/2012/07/heavy-metal-pollution-of-water.html